Amplifier Design in ADS

Characterization of High Power Devices

A Short Course Covering Component-Level Modeling and Measurement, Circuit Design and Analysis and System Modeling

Your Calibration, Measurement & Modeling Solutions Partner! Characterization of High Power Devices

Abstract - Device characterization is an essential process in many aspects of research, development and testing of RF and microwave devices. In this course, we will explore various interconnected topics of device characterization that form the amplifier design flow. Topics include pulsed IV and S- parameters for compact model extraction, load pull for model validation and measurement, amplifier design and IC stability analysis, X-parameter modeling and system-level simulations. Instructors from Maury Microwave, Agilent Technologies and AMCAD Engineering will provide instruction and demonstrations.

Your Calibration, Measurement & Modeling Solutions Partner! Characterization of High Power Devices

Load Pull S-Parameters IV Curves

Compact Models Amplifier Design

Circuit Simulation Harmonic Balance

Amplifier Stability X-Parameters

What do they mean? Are they somehow related?

Your Calibration, Measurement & Modeling Solutions Partner! System Design from Compact Models

Component level Circuit level System level

VNA based FET Compact Pulsed IV and RF Compact FET IC Design & load pull model Validation IC X-Parameter Simulation at measurements model extraction Stability analysis & Refinement model system level

TOOLS

PIV TUNERS ADS ADS ADS ADS PNA-X IVCAD PNA-X IVCAD (PNA-X) IVCAD ICCAP IVCAD STAN

Your Calibration, Measurement & Modeling Solutions Partner! System Design from X-Parameters

Component level Circuit level System level

IC Design & IC X-Parameter Simulation at Stability analysis X-Parameters model system level load pull

TOOLS

TUNERS ADS ADS ADS PNA-X NVNA IVCAD (PNA-X) IVCAD STAN

Your Calibration, Measurement & Modeling Solutions Partner! System Design from Measurements

Component level Circuit level System level

VNA based IC Design & load pull IC X-Parameter Simulation at Stability analysis model system level

TOOLS

TUNERS ADS ADS ADS PNA-X (or PSG/PSA) IVCAD (PNA-X) IVCAD STAN

Your Calibration, Measurement & Modeling Solutions Partner! Design flow entry points Component level Circuit level System level

VNA based FET Compact Pulsed IV and RF Compact FET IC Design & load pull model Validation IC X-Parameter Simulation at measurements model extraction Stability analysis & Refinement model system level

VNA based IC Design & load pull IC X-Parameter Simulation at Stability analysis model system level

Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! Instructor – Gary Simpson

Gary Simpson received his Bachelor degree from DeVry Institute of Technology in 1972, and his Masters degree from Arizona State University in 1978. He has been involved with microwave measurements since 1973, starting with device characterization through manual load pull on microwave power transistors at his first job at Motorola. He has been with Maury Microwave since 1982, where he began developing components and fixtures for microwave measurements, including network analyzer calibration standards and techniques. Gary is a pioneer in device characterization systems; in 1987 he developed one of the earliest automated slide-screw tuners for advanced load pull measurements. Since then, he has been responsible for much of the on-going development of device characterization techniques, methodologies and systems. He is currently Chief Technical Officer at Maury Microwave Corp.

Your Calibration, Measurement & Modeling Solutions Partner! Instructor – Tony Gasseling

Tony Gasseling received his PhD from University of Limoges in 2003. The topic of his PhD was “A new characterization technique of "Four hot S parameters" for the study of nonlinear parametric behaviors of microwave components”. Throughout his education, Tony focused on advanced device characterization techniques with emphasis on transistor modeling. In 2004, with the support of the European Social Fund, he launched AMCAD Engineering, a spin-off of the XLIM Laboratory (Limoges-FRANCE). Today, AMCAD Engineering employs 10 PhDs to support a strong innovation in the field of testing solutions for RF and microwave circuits.

Your Calibration, Measurement & Modeling Solutions Partner! Instructor – Stephane Dellier

Stéphane Dellier received his MSc degree and PhD degree in electrical engineering from XLIM laboratory, University of Limoges, France, respectively in 2001 and 2005. His PhD research is focused on microwave circuits design.

In 2004 he co-founded AMCAD Engineering, company providing new RF and microwave solutions to semiconductor professionals. He is currently project leader at AMCAD Engineering focused on the development of IVCAD software platform for characterization and modeling of RF devices.

Your Calibration, Measurement & Modeling Solutions Partner! Instructor – David Ballo

David Ballo is a Senior Application Engineer with 33 years of experience at Agilent Technologies’ Component Test Division in Santa Rosa, California. After graduating from the University of Washington in Seattle, he spent ten years in R&D designing analog and RF circuits for signal analyzers. Since then, he has worked on developing and presenting seminars and papers, and writing application notes and technical articles on a wide variety of network- and spectrum-analyzer measurement topics.

Your Calibration, Measurement & Modeling Solutions Partner! Instructor – Al Lorona

Al Lorona is an Application Engineer who helps customers use SystemVue and other Agilent Technologies EDA products more effectively and creatively. With 24 years of experience at Hewlett-Packard and Agilent he is a seasoned presenter, teacher and sales team member. Al is based in southern California.

Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! Large-Signal Transistor Models

Convergence Operating range

Physic model

Compact Extrapolation Physical insight model Accuracy

Behavioral model

Easy modeling Usability for Circuit design process

Your Calibration, Measurement & Modeling Solutions Partner! Commercial compact FET models

• Mostly used models for GaN HEMTs

Number of Electro-thermal Trapping Original Device FET models parameters effect Effects Context Curtice3 [1] 59 No No GaAs FET

CFET [2] 53 Yes No HEMT

EEHEMT1 [3] 71 No No HEMT

Angelov [4] 80 Yes No HEMT/MESFET

AMCAD HEMT1 [5] 65 Yes Yes GaN HEMT

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

1.6 1.18 1.4 Rd 1.16 y = 0.0049x + 0.6889 1.14 1.2 y = -0.0008x + 1.1543 1.12

1 Rs 1.1 Idss Rs, Rd Rs, 1.08 0.8 y = 0.0029x + 0.6375 1.06 0.6 1.04 0.4 1.02 0 50 100 150 200 0 50 100 150 200 T°C T°C

Non-linear Thermal Trapping Small-Signal IV Model capacitances model effects

Ri Dgs=f(Vgs) Dgs=f(Vgs,T) Cds Dgd=f(Vgd,T) Rg τ Dgd=f(Vgd) Lg Gm Ids=f(Vgs,Vds) Ids=f(Vgs,Vds,T) Cpg Gd Ls Cgs Cgs=f(Vgs) Ids=f(Vgs_trap,Vds,T) Cpd Cgd Cgd=f(Vgd) Ld Rgd Rs Rs=f(T) Rd Rd=f(T) Various effects are successively added

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed IV measurements

Short pulse : Quasi-isothermal conditions

Low duty cycle : Constant mean temperature

Quiescent bias point : Thermal conditions fixed

Several quiescent bias point

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed IV measurements

• Pulsed IV measurements must be accurate from low to high voltage/current values

• Accurate IV data = . Reliable current source . Transconductance . Leakage current . Ideality factor schottky diode

IVCAD

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed IV measurements

How to get accurate pulsed IV measurements ?  PIV system

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed IV measurements

How to get accurate pulsed IV measurements ? Gate 15 bits + sign Drain 16 bits +20V 250V

15 bits + sign

16 bits 25V -20V

Pulse shape monitoring

20ns time resolution

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed IV measurements

How to get accurate pulsed IV measurements ? 1A 33µA 4mA AM212 1A Gate access 100mA 3,3µA 400µA 100mA 10mA 330nA 40µA 10mA 1mA 33nA 4µA 1mA 0mA

-20V -2V 0V 650µV 65µV Measurement Resolution 20mV 2mV Voltage Absolute Accuracy 20V 2V Voltage Range

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed IV measurements

How to get accurate pulsed IV measurements ?

10A AM221 200µA 20mA Drain access

1A 22µA 2mA 0A

Measurement Resolution 0,53mV 4,9mV Voltage Absolute Accuracy 50mV 500mV Voltage Range 0V 25V 250V

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed S-parameter measurements

Pulsed S parameter measurements

Bias Bias

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed S-parameter measurements

The first & most important point : • Pulsed S parameter measurements must not be noisy

• Small S2P measurement variation = strong influence over the linear model extraction : optimization algorithm

Requirements :

IVCAD

Dynamic range in pulsed mode > 90dB for Duty Cycle ~ 5%

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed S-parameter measurements

Pulsed S-parameter measurements must not be noisy at low duty cycle with narrow pulse width Pulse detection methods

Wideband detection Narrowband detection

Receiver samples IF filter Receiver samples IF filter

• No pulse desensitization • Narrower minimum pulse width than • Increased noise with narrow pulse width due wideband pulse to wider IF bandwidth • Reduced dynamic range with low duty cycle • Limited pulse width by maximum available IF due to pulse desensitization by 20*log(duty bandwidth cycle)

Your Calibration, Measurement & Modeling Solutions Partner! PNA/PNA-X Noise reduction techniques and performances Peak-to-peak noise with wideband detection at 10% duty cycle

No averaging in calibration and measurements Averaging 20 times in calibration and measurements Pulse width (IFBW)

0.03 dB 10 us 0.005 dB (150 kHz) 0.04 dB 5 us 0.006 dB (280 kHz) 0.06 dB 0.012 dB 1 us (1.5 MHz) 0.09 dB 500 ns 0.013 dB (3 MHz)

Your Calibration, Measurement & Modeling Solutions Partner! PNA/PNA-X Noise reduction techniques and performances Dynamic range with wideband detection at 10% duty cycle with 10 us, 5 us, 1 us, 500 ns pulse width No averaging in calibration and measurements, 1% Averaging 20 times in calibration and measurements, smoothing on 1% smoothing on

Your Calibration, Measurement & Modeling Solutions Partner! PNA/PNA-X Noise reduction techniques and performances Peak-to-peak noise at 10% duty cycle

Wideband detection with 20 times averaging in Narrowband detection with no averaging in calibration calibration and measurements and measurements Pulse width

0.005 dB 10 us 0.009 dB

0.006 dB 5 us 0.009 dB

0.012 dB 0.012 dB 1 us

0.013 dB 500 ns 0.011 dB

Your Calibration, Measurement & Modeling Solutions Partner! PNA/PNA-X Noise reduction techniques and performances Dynamic range with narrowband detection at 500 ns pulse width

Hardware No Averaging, 1% smoothing on, 500 Hz IF bandwidth gating

Crystal filter >100 dB at 10% >100 dB at 5% 90 dB at 1% 85 dB at 0.5% Software gating

Spectral nulling

Your Calibration, Measurement & Modeling Solutions Partner! VNA performance comparisons E836x Legacy PNA N524xA PNA -X N522xA New PNA

Pulse generator External Internal/External Internal/External Pulse modulator External Internal/External Internal/External Wideband detection Max BW/Min PW 35 kHz / 50 us 15 MHz / 100 ns 15 MHz / 100 ns High level noise* 0.006 dBrms 0.002 dBrms 0.002 to 0.003 dBrms Dynamic range** 114 to 123 dB 124 to 129 dB 127 dB Narrowband detection Min IF gate width 20 ns <20 ns <20 ns Dynamic range*** 85 dB <105 dB <105 dB

* Specified as trace noise magnitude, at 20 GHz, at 1 kHz IF bandwidth ** Specified performance at 20 GHz, at 10 Hz IF bandwidth *** Measured performance at 10 GHz at 10 Hz IF bandwidth, 1% duty cycle Your Calibration, Measurement & Modeling Solutions Partner! PNA/PNA-X internal pulse access • Internal or external master pulse (PULSE SYNC IN) • Synchronized data acquisition (P0) • Synchronized internal pulse generators (P1 – P4) with independent delay and width • Internal or external drive for modulators or receiver gates

N1966A Pulse I/O adapter

Search “1408-21” on www.agilent.com

Your Calibration, Measurement & Modeling Solutions Partner!

Pulsed IV/RF parameter measurements

How to get accurate pulsed IV measurements ?

Synchronisation between Pulse IV and pulse S parameters

Your Calibration, Measurement & Modeling Solutions Partner! Pulsed S-parameter measurements

How to get accurate pulsed IV measurements ?

Synchronisation between Pulse IV and pulse S parameters

Your Calibration, Measurement & Modeling Solutions Partner! Parameter extraction methodology

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

1.6 1.18 1.4 Rd 1.16 y = 0.0049x + 0.6889 1.14 1.2 y = -0.0008x + 1.1543 1.12

1 Rs 1.1 Idss Rs, Rd Rs, 1.08 0.8 y = 0.0029x + 0.6375 1.06 0.6 1.04 0.4 1.02 0 50 100 150 200 0 50 100 150 200 T°C T°C

Non-linear Thermal Trapping Small-Signal IV Model capacitances model effects

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

Small-Signal

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling The small-signal• Extraction model presents of extrinsic and intrinsic parameters: two parts :

Lg Rg Rd Ld Transistorintrinsic - an intrinsic circuit G D intrinsèquetransistor Cpg Cpd

- an extrinsic circuit related to the Rs • Extrinsic parameters parasitic elements Ls - pad capacitances Cpg, Cpd S - port metallisation inductances Lg, Ld, Ls - port ohmic resistances Rg, Rd, Rs Cgd Rgd GrilleGate Drain An algorithm developped at the • Intrinsic parameters Cgs IRCOM lab allows- channel to capacitancesoptimize the Cgs, Cgd Gm Rds Cds extrinsic elements- voltage in-controlled order to current get source with Ri transconductance gm and transit time delay intrinsic parameterstau that do not SourceSource -j depend on the- ohmic frequency resistances Ri, Rgd Transistorintrinsic intrinsèque transistor Gm = Gm 0  e - output capacitance Cds and resistance Rds

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling • Extraction of extrinsic and intrinsic parameters:

• Foundry parameters (configuration window)

Rsquare (Ω/sq) - square resistance

LDS (m) - drain-source distance Ztotal (m) - total gate development

Calculus of Channel resistance

Rc = Rsquare * (LDS/Ztotal)

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling • Extraction of extrinsic and intrinsic parameters:

Vgs>>Vp; Vds=0V

Theory: Explicit computation of the extrinsic parasitic elements Rg, Rd, Rs, Lg, Ld, Ls

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling • Extraction of extrinsic and intrinsic parameters:

Vgs<

Theory: Explicit computation of the extrinsic parasitic elements : Cpd and Cpg

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling

Set min. and max. for each extrinsic • Extraction of extrinsic and intrinsic parameter - user choice parameters: - initiated by cold FET meas. There is only one set of extrinsic parameters for which intrinsic parameters are independent Optimization algorithm: annealing, No fast simulated diffusion from the frequency (intrinsic parameters calculus) For a given set of extrinsic parameters, intrinsic admittance matrix of the device is extracted from measured [S] parameters Fit ?

Yes

Multi-biasing extraction of the linear model

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling

Set min. and max. for each extrinsic parameter - user choice - initiated by cold FET meas.

Optimization algorithm: annealing, fast simulated diffusion (intrinsic parameters calculus)

Your Calibration, Measurement & Modeling Solutions Partner! Small signal FET modeling •The selection of several plots enable to get rid off unrealistic solutions (Resistance >=0 only) •Optimization can be launched simultaneously for all the points selected •Each linear model has the same extrinsic values

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

Non-linear Small-Signal capacitances

Your Calibration, Measurement & Modeling Solutions Partner! Nonlinear capacitances

• 1 dimension capacitances extracted along optimal load-line are preferred due to simplicity. 1D capacitance models with equations based on hyperbolic tangents are naturally charge conservatives • Output Capacitance Cds is linear – no voltage dependence (weak anyway)

 Cgd=f(Vgd) + Modeling simplicity. Very good convergence

 Cgs=f(Vgs)

Cgs Cgd  The charges in the transistor are conservatives. Vgd Vgs

Your Calibration, Measurement & Modeling Solutions Partner! Nonlinear capacitances Non linear capacitances Cgd • Feedback capacitance Cgd is a strong Cgd function of drain voltage. GaN devices

B C0 A C2

Vm Vp Intrinsic Vgd

Vgs variation

Vgd=Vgs-Vds~=-Vds Cgd capacitance extracted along optimal load-line for power amplification

Your Calibration, Measurement & Modeling Solutions Partner! Nonlinear capacitances

Cgs Input capacitance Cgs is a strong function of gate C1 voltage. Cgs B C2 The gate-voltage non-linearity also effects model’s A harmonic generation

Vgs variation C0

Vm Vp Intrinsic Vgs

Cgs capacitance extracted along optimal load-line for power amplification

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

Non-linear Small-Signal IV Model capacitances

Your Calibration, Measurement & Modeling Solutions Partner! Diodes

Selection of curve without Gate Current + 1 or 2 curves With Gate current

• Gate-drain and gate-source diode equations include forward conduction of gate current

Your Calibration, Measurement & Modeling Solutions Partner! Output current source

Idss ↔ amplitude

Vdsp, A ↔ slope

P ↔ gd

Vp0 ↔ pinch-off M, P ↔ fitting parameters AlphaGm, Vgm, BetaGm, Vdm ↔ gm (derivative)

0.50

0.45

• AMCAD drain current model formulation allows to predict 0.40

0.35 very accurately the I-V curves, the partial derivatives gm 0.30

0.25 Gm (S) Gm and gd, the knee voltage and the transconductance 0.20 0.15 decrease at high current. 0.10 0.05

0.00 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 Vgs (V)

Your Calibration, Measurement & Modeling Solutions Partner! Breakdown generator

• Gate-drain Breakdown generator The breakdown phenomena leads to a current from the drain to the gate when the device is pinched-off and for high values of Vds voltage. In this case, the whole negative current characterized on the gate is seen in positive on the drain 800 200

600 100

400 0

200 -100

Ids (mA) Ids Igs (mA) Igs

0 -200

-200 -300 0 50 100 150 200 250 0 50 100 150 200 250 Vds (V) Vds (V) A polynomial expression with order 4 is necessary to model the cross of breakdown curves, with varies depending on the process

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

1.6 1.18 1.4 Rd 1.16 y = 0.0049x + 0.6889 1.14 1.2 y = -0.0008x + 1.1543 1.12

1 Rs 1.1 Idss Rs, Rd Rs, 1.08 0.8 y = 0.0029x + 0.6375 1.06 0.6 1.04 0.4 1.02 0 50 100 150 200 0 50 100 150 200 T°C T°C

Non-linear Thermal Small-Signal IV Model capacitances model

Your Calibration, Measurement & Modeling Solutions Partner! Thermal effects

• Temperature dependence with ambient or chuck temperature 0.9 1.0 0.5 0.8 0.7 -40°C 0.8 25°C 0.4 150°C 0.6 0.6 0.3 0.5

0.4 0.4 0.2

Ids (A) Ids (A) 0.3 Ids (A) 0.2 0.1 0.2 0.1 -0.0 0.0 0.0 -0.1 -0.2 -0.1 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 Vds (V) Vds (V) 1 Vds (V) • Static and Dynamic self-heating effects 1.0 Static 0.8

0.6 2  Dynamic

0.4 Ids (A) 0.2

-0.0

-0.2 0 20 40 60 80 100 Vds (V)

Your Calibration, Measurement & Modeling Solutions Partner! Thermal effects

Your Calibration, Measurement & Modeling Solutions Partner! Thermal effects Thermal resistance extraction → coincidence method Ids same Vgs DC, Tchuck1 = 25°C

Pulsed from (0,0), Tchuck2 = 100°C

DC curve Tj1 = Tchuck1 + Rth*Pdiss1

Pulsed curve Tj2 = Tchuck2 + Rth*Pdiss2 Vds = 0 At intersection point Tj1 =Tj2 => Rth = (Tchuch2 – Tchuck1)/ Pdiss1 Tchuck1 + Rth*Pdiss1 = Tchuck2

Your Calibration, Measurement & Modeling Solutions Partner! Thermal effects

Thermal impedance extraction – by measurements

Your Calibration, Measurement & Modeling Solutions Partner! Thermal effects

• Drain current is only temperature dependent model element Takes into account ambient temperature and self-heating effects Thermal analog circuit to model self-heating and elevated heat sink temperatures

Drain access

Gate access

RC cells

AMCAD original current source Dissipated Power Diodes Non linear Capacitances Thermal circuit Breakdown source Source access Extrinsics

Your Calibration, Measurement & Modeling Solutions Partner! Compact FET model extraction flow

1.6 1.18 1.4 Rd 1.16 y = 0.0049x + 0.6889 1.14 1.2 y = -0.0008x + 1.1543 1.12

1 Rs 1.1 Idss Rs, Rd Rs, 1.08 0.8 y = 0.0029x + 0.6375 1.06 0.6 1.04 0.4 1.02 0 50 100 150 200 0 50 100 150 200 T°C T°C

Non-linear Thermal Trapping Small-Signal IV Model capacitances model effects

Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects Ibk

Igd(T°) • Charging and discharging of traps has influence on Ids and leads to current collapse. This is Lg Rg Cgd Rgd Rd(T°) Ld described in the model by trapping effects modifying the gate command and separated into gate and drain lag sub-circuits Cpg Vgs Vds Cpd

Drain access Gate- & Drain-lag Ids (Vgs_int(t-τ), Vds(t), T°)

Gate access Cgs Vgs_int Igs(T°) Vgs_int Cds

Transistor intrinsèque Rs(T°) AMCAD original current source Dissipated Power Diodes Non linear Capacitances Thermal circuit Breakdown source Source access Extrinsics Ls

Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects

• Charge of the capacitance = Ionized traps Charge through Rcapture, Emission through Rémission

signal reshaping C R Diode C8 circuit Port Rcapture diode Vout

R Port Remission Vin

Tuning of the magnitude of the Diode = dissymmetry of the trapping effects capture and emission process

Fundamental assumption : dissymetry of the capture and emission process

Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects

Measurements to extract Gate-lag at very low dissipated power

Id (A) Id Id (A) Id

Time (ms) Vds(V)

Response to an ideal square Emission shaped pulsed voltage (A) Id

Time (ms)

Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects

Measurements to extract Drain-lag at very low dissipated power

Id (A) Id Id (A) Id

Time (ms) Vds(V)

Capture

Emission Id (A) Id

Time (ms) Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects

• Bias dependant gate lag -> current reduction over the entire characteristic Bias dependent drain lag -> current reduction and shifts the knee-voltage to a higher Vds Model covers knee walkout to avoid errors in calculation of output power.

0.7 H

0.6 gate-lag : Id ↘ => Pout ↘ 0.5

0.4

Id ↘ 0.3 drain-lag : => Pout ↘ Ids (A) (H) Vknee↗ 0.2

0.1

0.0

-0.1 0 5 10 15 20 25 30 35 40 45 50 55 60 Vds (V)

Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects

• Decreasing form of the mean output current only reproduced with traps accurately modeled 0.35 4 H H Ids ↘ 0.30 meas 3 model without traps model 0.25 2

model with traps model

(A)

Ids (A) (H) Pout W (H) Pout

Ids (A) (H) (H) 0.20 1

Ids Pout W (H) Pout (H)

0.15 0 -10 -5 0 5 10 15 20 25 30 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Pin (W) 0.35 4 Pin( dBm) H H Pout ↘ 0.30 3

0.25 2

Pout (W) Pout meas

Ids (A) (H) model without traps model Pout W (H) Pout

Ids (A) (H) (H) 0.20 1 Pout W (H) Pout (H) model with traps model

0.15 0 -10 -5 0 5 10 15 20 25 30 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Pin( dBm) Pin (W) A Drain-Lag Model for AlGaN/GaN Power HEMTs, Jardel, O. ; Charbonniaud, Microwave Symposium, 2007. IEEE/MTT-S International 2007

Your Calibration, Measurement & Modeling Solutions Partner! Trapping effects

• A Non Linear Electrothermal Model of AlGaN/GaN HEMT for Switch Applications Charbonniaud, C. and al. (AMCAD) ; Compound Semiconductor Integrated Circuit Symposium (CSICS), 2012 IEEE , Page(s): 1 - 4

• A distributed electro-thermal model of AlGaN/GaN HEMT power-bar derived from the elementary cell model Xiong, A. and al. (AMCAD) ; Microwave Integrated Circuits Conference (EuMIC), 2012 7th European, Page(s): 64 - 67

•A non linear power HEMT model operating in multi-bias conditions Charbonniaud, C and al. (AMCAD) ; Microwave Integrated Circuits Conference (EuMIC), 2010 European, Page(s): 134 - 137

• A Scalable and Distributed Electro-Thermal Model of AlGaN/GaN HEMT Dedicated to Multi-Fingers Transistors •Xiong, A. and al. (AMCAD) ; Compound Semiconductor Integrated Circuit Symposium (CSICS), 2010, Page(s): 1 - 4

Your Calibration, Measurement & Modeling Solutions Partner! Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! Model Validation

• Large-signal

Model validation of a 8x75 µm GaN HEMT with Model validation of a 8x400 µm GaN HEMT with load-pull measurements performed at 6 GHz load-pull measurements performed at 3 GHz for for optimum PAE load impedance in class-AB the optimum Pout load impedance in class-B

40 40 60 60 meas. meas. 35 model 30 model

30 Pout 40 40 PAE(%) PAE Pout PAE (%)PAE 25 20 20 20 20

15 10 0 gain 0

10 gain Pout (dBm) and Gain (dB) Gain and (dBm) Pout 5 0 (dB) Gain and (dBm) Pout -20 -20 -10 -5 0 5 10 15 20 25 30 -5 0 5 10 15 20 25 30 Pin dBm Pin dBm

Your Calibration, Measurement & Modeling Solutions Partner! Model Validation

With non optimal loads : Time domain load pull measurements Deembedding in the intrinsic reference plane Parasitic extrinsic elements must be accurately extracted by previous S parameter measurements

Your Calibration, Measurement & Modeling Solutions Partner! Model Validation

What are the unique or specific requirements for load pull with regards to model validation?

-Independent powers at each frequency (fo, 2fo…)

-Independence of source impedance match

Your Calibration, Measurement & Modeling Solutions Partner! Introduction to load pull

1) Vary impedance presented to DUT (active device, transistor)

Highest Pout 2) Measure Pout, Gain, Efficiency…

3) Determine best matching impedance

4) Design matching network (EEsof ADS)

Your Calibration, Measurement & Modeling Solutions Partner! Impedances and impedance tuners

VSWR α Gamma α 1/Ω 10:1 VSWR = Γ=0.82 = 5Ω 20:1 VSWR = Γ=0.9 = 2.5Ω

Γ = a/b

Mechanical Tuner

Probe Y Gamma comes from probe X (slug) inserted into airline

Airline

X Y Probe

Airline

Your Calibration, Measurement & Modeling Solutions Partner! Traditional load pull measurements

(optional )

In Traditional Load Pull, delivered output power is calculated from Power Meter de-embedded through S-Parameter block and Impedance Tuner Available input power is calculated from gain lookup table created during power calibration or from input Power Meter and then de-embedded through S-Parameter block and Impedance Tuner A reflect power meter can be used to calculate delivered input power by measuring the reflected power through a reverse coupler, however the accuracy decreases as the mismatch between source impedance and device input impedance increases. Your Calibration, Measurement & Modeling Solutions Partner! What about large-signal Zin?

Large signal input impedance, Zin, changes as function of: - Drive power - Zload

Traditional load pull matches source impedance at single power, not taking into account varying Zin during power sweep

Your Calibration, Measurement & Modeling Solutions Partner! What about large-signal Zin?

Gain values look low because only Pin,available is used… reflected power due to mismatch is not taken into account

Traditional load pull only reports Transducer Gain

Your Calibration, Measurement & Modeling Solutions Partner! Vector-receiver (real-time) load pull Network Anal yzer

Low-loss Low-loss 50Ω Load Coupler Coupler Signal Source Amplifier Impedance Tuner Impedance Tuner

22 112 2 2 2 P b2 1  load P b  a  b 1   out   out 2 2 2  load  Gp  22 P 22 in, del a1 1  in  112 2 2 2 PP P a  b  a 1   out in, del in, del 1 1 1  in  PAE  22 PDC

Your Calibration, Measurement & Modeling Solutions Partner! Vector-receiver (real-time) load pull

Gain values look low because only Knowing Zin allows us to calculate Pin,available is used… reflected power due Power Gain, taking into account to mismatch is not taken into account mismatch thereby showing true gain potential of device

Your Calibration, Measurement & Modeling Solutions Partner! Vector-receiver (real-time) load pull Traditional LP Vector Receiver LP Pre-Characterization Required Recommended (not required) Number of Points More points = greater Minimum points required accuracy (even with (no impact on accuracy) interpolation) Tuner De-embedding Critical! (Accuracy relies No tuner de-embedding on de-embedding)

Network Analyzer Power Meter

Spectrum Analyzer

Power Sensor

Low-loss Power Low-loss 50Ω Load Coupler Coupler Signal Source Amplifier Impedance Tuner Impedance Tuner Sensor Signal Source Amplifier Impedance Tuner Impedance Tuner

Your Calibration, Measurement & Modeling Solutions Partner! Vector-receiver (real-time) load pull

Traditional LP Vector Receiver LP

Verification Procedure ΔGt Zin vs. Zload comparison complex conjugate ΔGt matched verification complex conjugate matched verification

Your Calibration, Measurement & Modeling Solutions Partner! Vector-receiver (real-time) load pull

*A reflect power meter can be used to calculate delivered input power by measuring the reflected power through a reverse coupler, however the accuracy decreases as the mismatch between source impedance and device input impedance increases. Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

VSWR α Gamma α 1/Ω 10:1 VSWR = Γ=0.82 = 5Ω 20:1 VSWR = Γ=0.9 = 2.5Ω

Γ = a/b

Mechanical Tuner X Y Probe Probe Gamma comes from probe

Airline (slug) inserted into airline Γ<1 Airline

Active Tuner Gamma comes from signal generator and amplifier Γ=1 or Γ>1

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Maximum Tuning Range (exaggerated for effect)

Tuner Tuner + Tuner + Cable + Probe Cable

Losses of cables, probes, test fixtures reduces tuning range and cannot be overcome using traditional load pull methods 84 Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull External Tuners

For Harmonic Load Pull, Traditional Load Pull systems require one mechanical tuner per frequency per DUT side To tune Fo, 2Fo and 3Fo at the same time requires 3 tuners (using multiplexer or cascaded methods) It is possible to build 3 tuners in 1 box, but it becomes 2-3x longer and 2-3x more expensive Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Γ=0.99 Γ=0.99

Tuner + Cable + Probe

Gamma advantage of Active Load Pull  Losses of cables, probes, test fixtures reduces tuning range, and can be overcome using larger amplifiers

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Active Fo Load Pull

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Hybrid-Active Fo Load Pull

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Active Fo, 2Fo, 3Fo Load Pull

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Hybrid Active Fo, 2Fo, 3Fo Load Pull

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull Measured Data – Passive VS Active

Excellent Agreement

Traditional Load Pull Active Load Pull

Your Calibration, Measurement & Modeling Solutions Partner! Active and hybrid-active load pull

Passive Fo Active 2Fo, 3Fo

Γ2Fo=0.988 @ DUT on-wafer!

One of many configurations of hybrid/active load pull

Your Calibration, Measurement & Modeling Solutions Partner! Vector-receiver (real-time) load pull

Load pull for model validation Compact model  ADS

Load pull for measurements Measurements  ADS

Your Calibration, Measurement & Modeling Solutions Partner! Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! Which Type Are You?

Designers usually fall into one of two camps:

Compact or X-parameter Measured LP data models Use any of the setups in the Must use a “Data-based LP” Load Pull Design Guide component HB S-parameter analysis

• Can sweep • Can sweep • Can optimize • Can optimize A wide variety of simulations Good for designing matching possible; great data displays networks

ADS is set up to handle any case.

Your Calibration, Measurement & Modeling Solutions Partner! Simple load pull – introduction to concepts

Which Impedance should I present the Device at the in- and output (over a broad frequency range to over the higher harmonics) to have a maximal Pdel, PAE and Gain with minimal distortion (XdB-compression, EVM, ACLR, etc.)? Your Calibration, Measurement & Modeling Solutions Partner! Device performance due to Zl and Zs

f1 f2 f3 freq

External source (or previous Output match. stage) Input match. network network

External load (or next stage) f1 f2 f3 freq

Your Calibration, Measurement & Modeling Solutions Partner! Fundamental load pull Why? Quick “sanity check”; adjust sampled area

f1 f2 f3 freq

Load tuner Source tuner Guess reasonable Available values for all source variables. power f1 f2 f3 freq Adjust, if necessary. constant Your Calibration, Measurement & Modeling Solutions Partner! Fundamental load pull with power sweep Why? See gain compression and f1 f2 f3 freq constant power delivered data

Load tuner Source tuner

Available source power f1 f2 f3 freq swept freq Your Calibration, Measurement & Modeling Solutions Partner! Fundamental source pull

Why? Source impedances affect gain primarily, but also PAE

f1 f2 f3 freq

Load tuner Source tuner

Available source power f1 f2 f3 freq constant Your Calibration, Measurement & Modeling Solutions Partner! Fundamental load pull with parameter sweep Sweep any parameter - source frequency, bias, stability network parameter values, etc. Why? Investigate device performance more thoroughly

f1 f2 f3 freq

Load tuner Source tuner

Available source power … f1 f2 f3 freq constant freq Your Calibration, Measurement & Modeling Solutions Partner! Harmonic load phase sweep Why? Harmonic impedances matter, but usually want high reflection f1 f2 f3 freq

Load tuner Source tuner

Sweep input power to see constant power f1 f2 f3 freq delivered data freq

Your Calibration, Measurement & Modeling Solutions Partner! Source stimulus responses

IMD from 2-tone source

ACLR from modulated source

Gain comp. curves from source power sweep Your Calibration, Measurement & Modeling Solutions Partner! Amplifier design in ADS

What is available for the non-linear device? Model  run load pull simulations to determine optimal matching and biasing conditions for amplifier design Measured Load Pull Data  analyze measured data and determine optimal matching and biasing conditions for amplifier design

Your Calibration, Measurement & Modeling Solutions Partner! Start with fast, simple load pull

Most parameters are passed to tuner inside “instrument” subcircuit

Device Model from Design Kit

Your Calibration, Measurement & Modeling Solutions Partner! Start with fast, simple load pull

• Available source power Refine held constant sample • Guess optimal Zsource space and harmonic Zs

Source Power Source Power = 5 dBm = 12 dBm

Your Calibration, Measurement & Modeling Solutions Partner! Load pull with power sweep

Your Calibration, Measurement & Modeling Solutions Partner! Select load for highest Pdel or highest PAE

, dBm , Pdel

PAE

Your Calibration, Measurement & Modeling Solutions Partner! Contours versus swept parameter (frequency)

28 dBm contour at 750 MHz

28 dBm contour at 1.25 GHz

Your Calibration, Measurement & Modeling Solutions Partner! Dependency on phase of gamma at harmonic

Your Calibration, Measurement & Modeling Solutions Partner! Sweep Gate Bias

Results with gate bias = 2.25V

Your Calibration, Measurement & Modeling Solutions Partner! Constant power del. load pull with two tones

Your Calibration, Measurement & Modeling Solutions Partner! Load pull with WCDMA signal

Read modulated data from file. Scale signal amplitude by optimizing “SFexp” variable.

Your Calibration, Measurement & Modeling Solutions Partner! Maury measured data

• Examine contours and make trade-offs for optimal load condition • Use measured data files directly in impedance matching network design and optimization

Your Calibration, Measurement & Modeling Solutions Partner! Performance contours from Load Pull Data

1) Reads LP data file 2) Simulates S-parameters of network 3) Gets corresponding Tuner generates loads performance data in region you specify

Your Calibration, Measurement & Modeling Solutions Partner! Indep. variables and performance parameters

Frequency and input power constant

Your Calibration, Measurement & Modeling Solutions Partner! Plot performance contours from LP Data

Load giving Check the Contours, best Rectangular or Circular performance Regions

Frequency Slider

PAE Pdel Gt

Your Calibration, Measurement & Modeling Solutions Partner! Using power sweep of Load Pull data Why sweep power? See gain compression data.

Sweep values Sweep based on within range gamma_x, gamma_y of those in file values in file

Your Calibration, Measurement & Modeling Solutions Partner! Contours at specified gain compression

Why do contours look strange? Measurements at some loads were not valid. Your Calibration, Measurement & Modeling Solutions Partner! Choosing load: high efficiency or high power

, dBm , Pdel

PAE

Your Calibration, Measurement & Modeling Solutions Partner! Choosing optimal load at 2.17 GHz

Your Calibration, Measurement & Modeling Solutions Partner! Use measured data directly in optimization

This impedance should be the same as this.

Your Calibration, Measurement & Modeling Solutions Partner! Load Pull delivers the Impedance for the Matching Network Design

Frequency Sweep

Your Calibration, Measurement & Modeling Solutions Partner! Matching Network Design Smith Chart Utility Design impedance matching network(s) using existing techniques, or optimization

Your Calibration, Measurement & Modeling Solutions Partner! Matching Network Design Matching Utility (Broad Band) ADS Impedance Matching Utility –  Low-pass, high-pass, and band-pass, lumped element matching  Multi-section quarter-wave matching  Tapered-line impedance matching  Single-stub impedance matching  Several others

Your Calibration, Measurement & Modeling Solutions Partner! Using optimization to adjust parameter values

Preliminary output matching network to be optimized

Your Calibration, Measurement & Modeling Solutions Partner! Impedance optimization at 3 frequencies

Goal impedance Output matching network to be optimizedvalues:

Your Calibration, Measurement & Modeling Solutions Partner! Testing performance of completed amplifier One-tone harmonic balance Two-tone harmonic balance frequency and frequency and power sweep power sweep

Your Calibration, Measurement & Modeling Solutions Partner! Testing performance of completed amplifier

Your Calibration, Measurement & Modeling Solutions Partner! Verification of the of the Layout – EM Cosim

Run EM to obtain more accurate results

Input Output

EM Model

Analytical Model

Your Calibration, Measurement & Modeling Solutions Partner! PA Design Workflow

1) Run load pull simulation on the active device model or load pull measured data a. 1-tone, 1 input power load pull b. Power sweep to see gain compression c. Frequency or bias sweep d. Harmonic load phase sweep e. Constant output power with swept var f. Source pull g. 2-tones to see IMD h. Modulated signal to see ACLR 1) Choose optimal load impedances across frequency band 2) Use Smith Chart Utility or favorite matching tool to design preliminary matching network 3) Use optimization to adjust values 4) Use EM simulation and/or optimization to obtain more accurate results 5) Repeat steps 1-5 for to design source matching network 6) Test final design, including matching networks Your Calibration, Measurement & Modeling Solutions Partner! Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! Introduction to stability analysis Stability analysis is a critical step of RF design flow Classical methods are either not complete or too complex… Stability analysis need to be efficient (especially in large signal) - Rigorous - Fast - User-friendly - Compatible with commercial CAD softwares

Your Calibration, Measurement & Modeling Solutions Partner! Existing methods

• Linear analysis “small signal” – K factor – Normalized Determinant Function (NDF) – Stability envelope • Non-linear analysis “large signal” – Nyquist criterion – NDF – Bolcato, Di Paolo & Leuzzi, Mochizuki, …

Your Calibration, Measurement & Modeling Solutions Partner! Existing methods – linear analysis Widely used: K factor (also µ and µ’ now) - K>1 & |∆| <1: unconditional stability of two port network - K<1: conditional stability  stability circles

Unconditional stability Conditional stability Unconditional instability Limitations: Only indicates that a stable circuit will continue to be stable when loading it with passive external loads at the input or output

Do not guarantee the internal stability of the circuit !

Your Calibration, Measurement & Modeling Solutions Partner! Existing methods – linear analysis Potentially instable architectures for which K factor is not enough

Multi-stage power amplifier Multi-fingers transistor

OUT Gate Drain IN Source

Your Calibration, Measurement & Modeling Solutions Partner! Pole-zero identification principle

Hj() 30

10 RG

dB(Zsond)

|H| |H| (dB)

-10

200

100 RL

H (º) H 0 Frequency f0, Node ‘n’

-100

phase(Zsond) P domain -200 in 0.0 2.0E9 4.0E9 6.0E9 8.0E9 1.0E10 1.2E10 vout (iin ,f s ) Identification Freqfrequency (GHz) techniques Pole-zero plot 6 n Complex conjugate 4 poles with positive  ()sz i 2 poles real part -> start-up Hs() i1 p 0 of an oscillation

Im (GHz) zeros  ()s   j -2 j1 Oscillation frequency -4 = Module of the -6 imaginary part -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 Re (GHz) Your Calibration, Measurement & Modeling Solutions Partner! New stability analysis method - STAN

Suitable for both linear and non-linear stability analysis Very easy to use with any CAD tool Very easy to analyze results Relative stability information delivered Oscillation mode knowledge -> Help to find the suitable stabilization strategy Parametric Analysis implemented Monte-Carlo Analysis

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Integration with CAD

Perturbation CIRCUIT GENERATOR introduction node LOAD

in out

Var VAR P_1Tone Term Eqn VAR1 Input frequency cmp1198 Term1 fin=9.65 GHz Num=1 ampli Num=1 Pin=12 Z=50 Ohm X1 Z=50 Ohm P=polar(dbmtow(Pin),0) Input power Freq=fin

HARMONIC BALANCE I_Probe I_sond HarmonicBalance HB1 v_sond Freq[1]=fin Var VAR I_1Tone Order[1]=10 Eqn VAR3 SRC1 SS_MixerMode=yes f1=fstart+fin+0.0001e9 I_LSB=polar(0.0001,0) SS_Start=f1 f2=fend+fin SS_Stop=f2 UseAllSS_Freqs=yes MergeSS_Freqs=yes Var VAR Eqn VAR2 Start sweep frequency fstart=4.325 GHz Meas MeasEqn Eqn fend=5.325 GHz Stop sweep frequency meas1 n_point=101 Zsond=mix(v_sond,{-1,1})/mix(I_sond.i,{-1,1}) frequency=ssfreq-fin Number of frequency points

Nonlinear stability analysis template

EDA Tool Templates for Agilent ADS STAN tool AC simulation for linear integrated in IVCAD software HB simulation for non-linear User-friendly GUIs

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Integration with CAD Example 1 (Linear analysis)

Low frequency instability of a medium power 1.2 GHz FET amplifier built in hybrid microstrip technology Low frequency

V gg V dd oscillation

L cable C in L cable L hole  14MHz

C out L hole

L in GaAs FET C L out imn C omn

L L imn omn R L R s L hole L hole

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Integration with CAD ADS schematic

vout

iin

Note: It can also be done with a voltage probe connected in series at a circuit branch and observing the total admittance Your Calibration, Measurement & Modeling Solutions Partner! STAN – Integration with CAD

Simulated frequency response Z(j) 50

40 freq mag(Z) phase(Z) 1.000 MHz 10.332 90.003 30 11.00 MHz 216.618 91.941 21.00 MHz 270.189 -92.672 20

31.00 MHz 104.612 -90.829 dB(H) 41.00 MHz 65.997 -90.299 10 51.00 MHz 47.193 -89.998 61.00 MHz 35.371 -89.798 71.00 MHz 26.831 -89.667 0 81.00 MHz 20.060 -89.595 91.00 MHz 14.297 -89.585 -10 101.0 MHz 9.095 -89.647 0.00 0.25 0.50 0.75 1.00 1.25 1.50 111.0 MHz 4.145 -89.794 121.0 MHz 0.795 89.951 freq, GHz 131.0 MHz 5.958 89.554 141.0 MHz 11.599 88.969 100 151.0 MHz 18.047 88.123 161.0 MHz 25.766 86.902 171.0 MHz 35.480 85.120 50 181.0 MHz 48.404 82.446 191.0 MHz 66.727 78.252 201.0 MHz 94.580 71.219 211.0 MHz 138.977 58.377 0 221.0 MHz 199.477 33.980 231.0 MHz 219.444 -1.348 phase(H) 241.0 MHz 176.951 -28.478 -50 251.0 MHz 135.681 -42.995 261.0 MHz 108.466 -50.829 271.0 MHz 90.570 -55.440 281.0 MHz 78.205 -58.363 -100 291.0 MHz 69.241 -60.317 0.00 0.25 0.50 0.75 1.00 1.25 1.50 freq, GHz

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Integration with CAD Identification results

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Integration with CAD Centered on 20 MHz

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node

“All nodes are equal, but some nodes are more equal than others”

SISO transfer function → exact pole/zero cancellations are possible

Pole/zero cancellations are associated with the lack of controllability and/ or observability in the system

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node

Example: let us consider a complex circuit in which the oscillation is taking place in a part that is totally isolated from the node selected to perform the analysis

2e9 

Node ‘n’

vout (iin ,f s )  2e9

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node

However, the oscillation can be predicted if the node is connected in the part of the circuit that is not isolated

v out 2e9  Node ‘m’

(iin ,f s )

 2e9

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node • The analysis is performed at a node that is not “completely” isolated from the part where the oscillation is taking place, i.e. there is a weak electrical link between parts

2e9 

Node ‘n’

vout (iin ,f s )

 2e9

Quasi-cancellation  poles and zeroes almost cancelled  low degree of controllability/observability in the selected node  we are (electrically) far from the place where the oscillation is being generated  useful information for circuit stabilization

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node Recommendations In simple circuits with a clear feedback structure any node should serve for the analysis

Multistage power amplifiers → At least one analysis per stage

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node → Relevant information about the nature of the oscillation and the place in which it is being generated can be extracted → extremely useful for circuit stabilization V V Vbias_1 bias_ m bias_ n

6 6

4 4

2 2

0 0

Im (GHz)

Im (GHz) -2 clear -2 quasi-cancellation not observable -4 -4

-6 -6 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 Re (GHz) Re (GHz)

Your Calibration, Measurement & Modeling Solutions Partner! STAN - Selecting the node

Node ‘n’ v (i ,f ) out in s A- No oscillation B detected in the A FET2 common node FET1

FET3

FET5 B- Oscillation FET4 detected in the FET6 transistor node

 Odd mode (parametric frequency division)

 will determine the stabilization strategy

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Multi parameters

Analysis with swept parameter(s) Verification for various conditions (Pin, Zload, …) Checking of critical resonances Optimization of stabilization networks

PIN f0, Zload vout (iin ,f s ) Rstab

We might increase the stability margin of critical resonances when part of the system dynamics is not correctly modeled (or is likely to change).

Your Calibration, Measurement & Modeling Solutions Partner!

STAN – Multi parameters

Example 2 (HB analysis) Q1

Power splitter Two-stage X-Band MMIC Q2

power amplifier built in R L

HBT technology based on Q3 combiner Power R S

AsGa/GaInP process splitter Power Power f ,P splitter in in Q4

Parametric frequency division measured for Pin=13.8 dBm and fin=9.65 GHz 40 40

30 30

20 20

10 10

(dBm) 0

(dBm)

o o

P -10 P -10

-20 -20

-30 -30 -40 4.6 4.7 4.8 4.9 5 5.1 -40 9.4 9.5 9.6 9.7 9.8 9.9 Frecuencia (GHz) Frecuencia (GHz) fin (GHz) fin (GHz)

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Multi parameters

ADS schematic (parametric analysis on Pin)

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Multi parameters

Identification results: evolution of critical poles

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Multi parameters Example 3: RC network in series at the base of the transistors trying to increase resistance at f0/2 without significantly degrading performances at f0

Large signal stability analysis to find suitable values for RC

Guaranteeing sufficient stability margin considering technological dispersion Selected circuit: R=15Ω C=2.5pF

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Multi parameters

Example: 3-stage LDMOS DPA for SDR applications

Application requires absence of spurious for a wide range of operating conditions

Multivariable large-signal stability analysis versus input

frequency, input power and real S(1,1) and imaginary parts of load Unstable termination ZL. Stable loads loads freq (1.000GHz to 1.000GHz) Stablemod and (0.693 unstable to 0.990) regions in

Frequency division (f /2) detected polar(inestables_HB1..mod,inestables_HB1..phase) in the L plane for fin=500 MHz and Pin=17.1 dBm

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Monte Carlo

Example: L-Band medium power FET amplifier

Low frequency instability related to the input bias network

Stabilization by the inclusion of a gate-bias resistor RSTAB

Monte Carlo sensitivity analysis for different RSTAB (5 % dispersion in all circuit parameters)

40 40

20 20

0 0

 RSTAB = 44   RSTAB = 70 

-20 -20

Imaginary Axis(MHz) Imaginary Imaginary Axis(MHz) Imaginary

-40 -40 -0.2 -0.1 0 0.1 -0.2 -0.1 0 0.1 Real Axis (MHz) Real Axis (MHz)

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Performance optimization

Example: Ku-Band MMIC PA for active space antenna

Stable original circuit

Inter-branch stabilization resistances

RF in RF out

Natanael Ayllón Rozas “Développement des méthodes de stabilisation pour la conception des circuits hyperfréquences : Application à l’optimisation d’un amplificateur de RC stabilization puissance spatial.”, PhD Thesis, networks February 2011.

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Performance optimization

Example: Ku-Band MMIC PA for active space antenna All stabilization networks removed resistances maintained for topological reasons

RF in RF out

Parametric frequency division /2 instability

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Performance optimization

Example: Ku-Band MMIC PA for active space antenna

Optimized version resistances maintained for topological reasons

RF in RF out No oscillation detected, especially around F0/2

Stabilization resistances

Your Calibration, Measurement & Modeling Solutions Partner! STAN – Performance optimization

Example: Ku-Band MMIC PA for active space antenna Original

Results comparison Optimized

Your Calibration, Measurement & Modeling Solutions Partner! Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! What Exactly Are X-Parameters??? • Two words: behavioral models! • Provide a comprehensive description of a device’s nonlinear performance under varying conditions • Include the magnitude and phase of the fundamental signal, all of its harmonics and intermodulation products, and all of their dependence on source and load impedance, bias, etc. • Are cascadable like S-parameters

Page 167 December 2011 Why Are X-Parameters Revolutionary? • Provide predictable measurement-based nonlinear design • Generate nonlinear models much faster than traditional methods • X-parameters, ADS, and NVNA are used to: • Reconstruct time-domain waveforms • Calculate performance parameters such as ACPR, EVM, and PAE • Design multi-stage amplifiers and sub-systems • Optimize nonlinear system performance • Less design iterations required, resulting in shorter design cycle Business value: faster time-to-market! • Protect intellectual property

Page 168 December 2011 X-Parameters: Large Data Library with Many

Variables one series one chapter one page one book of books one bookshelf

[X]p,f,Vg,Vd1 [X]p,f,Vg1 [X]p,f1 [X]p1 [X]p,f,Vg,Vd,z1 [X]p,f,Vg,Vd2 [X]p,f,Vg2 [X]p2 [X]p,f2 [X]p,f,Vg,V,z2 [X]p,f,Vg,Vd3 [X]p,f,Vg3 [X]p3 [X]p,f3 [X]p,f,Vg,Vd,z3

Various Various Various Various Various drain voltages powers frequencies gate voltages impedances one library

Measurements take from tens of minutes to a several hours = depending on the size of the “library” one X-parameter file [X]p,f,Vg,Vd,z X-Parameters Span Range of Component Complexity Systems

Modules

Integrated Circuits

Devices

Page 170 December 2011 Measurements on Linear Components

All measurements at same frequency as stimulus

Page 171 December 2011 Measurements on Nonlinear Components

Measurements at many frequencies

Page 172 December 2011 It’s Really Even More Complex…

A1 A2

B B1 2

Page 173 December 2011 Now Add Mismatch at Input and Output

A1 A2

s L B B1 2

How do we practically measure the mismatch interaction between all of the signals?

Page 174 December 2011 X-parameter Concept:

Incident Scattered

Bk ( DC , A1 , A 2 , A 3 ,...) Multi-variate nonlinear map Large-signal  operating point ()F Xk ( DC , A1 ,0,0,0,...) Simple nonlinear map Small-signal perturbation, one frequency at a time +

Linear non-analytic map

()()*ST [(,)(,)]Xkl DC A11 a l X kl DC A a l

Page 175 December 2011 Extraction Tone Provides Small-Signal Perturbation For Each Harmonic

A1 A2

Source 1 provides large-signal drive

B a2 B1 2 a1

Set CW extraction tone frequency Source 2 provides extraction tone

(~ -20 dBc from B2 fundamental) Measure all signals at all ports (fundamental plus harmonics)

Repeat extraction-tone loop for each large-signal drive level, frequency, bias, etc.

Page 176 December 2011 X-Parameter Extraction: Form of Active Load Pull

Large-signal 50  Extraction tone measures match operating point dependency using two phase conditions

()()()*F k S k l T k l BXik ik()()() APX11  ik , jl APaX 11 jl  ik , jl APa 11 jl

Perform 3 independent experiments with fixed A1 using orthogonal phases of a1, a2

Input Ajl Output Bik (0) (Fk ) BXAPik ik  11  Im Im (1) (F ) k ( S ) k l (1) ( T ) k l (1)* BXAPXAPAXAPAik ik 11  ik , jl 11 jl  ik , jl 11  jl Re B(2) X ()F APkX  () S APA k l (2)  X () T APA k l (2)* Re ik ik 11 ik , jl 11 jl ik , jl 11  jl

For output port i, output harmonic k, input port j, input harmonic l Comparing PNA-X and NVNA X-Parameter System

X-parameters PNA-X

ADS

(Plus software options)

It’s easy and relatively cheap to turn a 4-port PNA-X into an NVNA Configuring a PNA-X for X-Parameters

Power sensor MXG (to drive comb generators) (for amplitude calibration)

ECal module (for vector calibration )

Comb generator 1 (phase reference)

Comb generator 2 PNA-X with NVNA options (for phase calibration) Why Add Tuners to an NVNA?

• With NVNA only, X-parameters are valid for mismatched conditions near central portion of Smith chart ( ~ < 0.5) • With NVNA and tuners, X-parameters can also be measured in highly mismatched conditions (e.g.  = 0.95) • Useful for high-power, multi-stage amplifiers, and power transistors that are designed to work far from a 50-ohm environment • Load-dependent X-parameters includes magnitude and phase of all harmonics as functions of power, device bias, and load impedances • Data can be immediately used in a nonlinear simulator as a large signal model for complex microwave circuit analysis and design Load-Dependent X-Parameters

• Extend X-parameters over entire Smith chart for high-gamma devices • Requires impedance tuners, which can be electromechanical, active, or a combination

Probe assembly X Y Probe Probe

Airline

• Magnitude - move probe up / down • Phase - move probe horizontally Carriage assembly

Slab-line assembly

NA_S11_4 PNA Advanced Topics, v. 1.5 S800 – November 2011 Summary X-parameters go beyond S-parameters • Comprehensive non-linear behavioral model • Easily measured with VNA hardware and accessories • Less design iterations provides faster time-to-market • For more theory, read new book “X-Parameters”

()()()*F k S k l T k l BXik ik()()() APX11  ik , jl APaX 11 jl  ik , jl APa 11 jl

Page 182 December 2011 Introduction to X-Parameters

X-Parameters can be generated from circuits inside of ADS

X-Parameters can be measured using PNA-X with NVNA X-Parameters from circuits

YouTube videos on X-parameters:

Part 1 of 4, Generating X-Parameter Models from Circuits: http://www.youtube.com/watch?v=FP54LL8C2rQ Part 2 of 4, Generating Load-Dependent X-Parameter Models: http://www.youtube.com/watch?annotation_id=annotation_760993&feature=iv&src_ vid=FP54LL8C2rQ&v=xSpKlBNEedY Part 3 of 4, Generating Two-Tone X-Parameter Models: http://www.youtube.com/watch?annotation_id=annotation_379020&feature=iv&src_ vid=xSpKlBNEedY&v=X0fJMQzzEjk Part 4 of 4, Using X-Parameter Models in ADS for Wireless Verification: http://www.youtube.com/watch?annotation_id=annotation_942060&feature=iv&src_ vid=X0fJMQzzEjk&v=jiti6Plullo Your Calibration, Measurement & Modeling Solutions Partner! – Instructor Introduction

– Pulsed IV/RF and Compact Modeling

– Load Pull

– Amplifier Design in ADS

– Stability Analysis

– X-Parameters

– System-level Simulations

Your Calibration, Measurement & Modeling Solutions Partner! System-level schematic

Your Calibration, Measurement & Modeling Solutions Partner! System-level simulations

Your Calibration, Measurement & Modeling Solutions Partner! System level simulations

YouTube videos on system-level design using X-parameters:

Using Analog/RF X-Parameter Models in System-Level Design: http://www.youtube.com/watch?v=CV5s1ZhPPx4

Your Calibration, Measurement & Modeling Solutions Partner!