Blending and Power Management Technologies for Greatly Improved Performance -or- Why is an RF guy doing Power Management?! Earl McCune, Ph.D., F-IEEE Thursday, Aug. 23, 2018

Texas Instruments Building E Conference Center 2900 Blvd. Santa Clara, CA 95051

6:30pm - 7:00pm: Dinner and Networking 7:00pm - 8:00pm: Talk and Q & A Outline

• State of the art in -based radio • Common physics with switching power converters

• Zero-Power Idle (ZPI) supply • Very-high Dimming Ratio (VHDR) efficient driver • Bridge rectifier elimination • Power factor correction

Earl McCune [email protected] Linear PA Efficiency Ceilings

• Entire output signal – peak Envelope PDF to peak – must fit within the linear PA load line Signal envelope • PA is scaled for signal peak power • Signal average power sets 0.03 communication range 0.025

0.02 • Low average power

(A) 0.015 C

I increases PA heat 0.01 – A direct consequence of 0.005 Ohm’s Law 0 0 0.5 1 1.5 2 2.5 3 3.5

GaAs HBT VCE (V)

Earl McCune [email protected] 3 Linear PA Efficiency: Business Impact

Efficiency vs. PAPR 5G-NR Cost vs. Efficiency

10 9 Power supply size Input Power 8 Power Dissipation 7 LTE 2G 6 5 4 3G 2.5G COST TX power 3 Heatsink 2G 2.5G 2 3G LTE size 5G-NR 1

Power / Output power (Normalized) power / Output Power 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Circuit Energy Efficiency • Signal design progression forces linear PA efficiency to decrease • Costs therefore rise – Higher input power is required (larger power supply) – Thermal management of the corresponding PA heat • Preferred radio efficiency range by industry: between 40 to 70 % • 5G must be profitable to build and operate – or it will fail

Earl McCune [email protected] 4 Physically Available Options

Actual objective: accuracy at-power

• Traditional approach: Linear Theory VDD – Modulate at small signal levels Vout= IR D ⋅ L R – Increase signal power with linear L – Maintains modulation accuracy, Large PSAT

• as long as all amplifiers remain linear (mathematical sense) VIN

• Alternative approach: Sampling Theory VDD – Sample the envelope with phase-modulated carrier

RL

PSAT VSUPPLY VRout = ⋅ L Large VIN RRL+ ON RON

Earl McCune [email protected] 5 Implementation Differences

Linear Operation 1 VDD Output range is bounded 0.8 • RL by the knee voltage 0.6

P • Signal always stays on the Large SAT 0.4 Drain Current (A) VIN load line 0.2

0 0 0.5 1 1.5 2 2.5 3 3.5

VDS (V)

VDD Switching Operation

0.03 ON state • Output range is bounded RL 0.025 by the ON resistance PSAT 0.02

Large VIN (A) 0.015 • Circuitry operates at the C I 0.01 endpoints of the load line RON 0.005 • Efficiency increases 0 0 0.5 1 1.5 2 2.5 3 3.5

VCE (V) OFF state Earl McCune [email protected] 6 Sampling Transmitter Operation

1 VVout SUPPLY ILOAD = = 0.8 RL RR L+ ON

0.6 • Phase modulated carrier samples the signal envelope 0.4 Drain Current (A) • Dynamic Power Supply (DPS) 0.2 sets the instantaneous

0 0 0.5 1 1.5 2 2.5 3 3.5 envelope value VDS (V) Dynamic Power Supply • Switch-mode mixer modulator 3 VSUPPLY (SM ) does the sampling at-

A(t) power Envelope DPS

• Switching forces use of polar cos(ωφtt+ ( )) At( )cos(ωφ t+ ( t)) Phase SM3 signal processing Modulated RF

Earl McCune [email protected] 7 Operating Modes: L-mode, C-mode, and P-mode

VSUPPLY Booth Surface VS , IS Control DPS

PDto heatsink 30 20 VDPS , IDPS New Interface 10 P = V * I 0 DC PA PA } -10 -20 -30 PA -40 PIN POUT -50 5.0 P-mode -60

RF Power 4.0 -70 (dBm) Power Output PA PD 3.0 15 -5 5 To heatsink 2.0 -15 -35 -25 1.0 -55 -45 PA Supply Voltage (V) Input RF Power (dBm) 0.0 • All power are 3-port circuits • 3 operating modes appear when both supply voltage (dynamic power supply (DPS)) and input RF power are varied – L-mode: conventional linear “PA” operation – C-mode: fully compressed operation Eridan operates in C-P mode – P-mode: low voltage “gain-collapse” region

 Earl McCune [email protected] 8 Measured Efficiency vs. Signal PAPR

70% • Use of switching 60% circuitry greatly 50% 5G NR improves LTE DL 40% measured LTE UL efficiency 30% 3G QAMs • Modulation Stack Efficiency 20% EDGE accuracy is 10% GSM-CE maintained 0% 0 2 4 6 8 10 12 14 • Modulation Signal PAPR (dB) generality is not compromised 16384 QAM LTE Downlink 5G-NR • Reported efficiency is fully linearized -51dB ACLR Earl McCune [email protected] 9 Backup: Switching PA Efficiency Bounds

100 RL/RON=100

80 RL/RON=30

5 4 R /R =10 5 L ON 3 4 60 2 3 1 2 0 1 -1 0 90.0 90.5 91.0 91.5 92.0 time, nsec 40 -1 6 90.0 90.5 91.0 91.5 92.0 5 time, nsec 4 3 20 2 1 Achievable Efficiency (%) 0 -1 90.0 90.5 91.0 91.5 92.0 time, nsec 0 9 0 1 2 3 10 10 10 10

fT / fo

• Maximum efficiency depends on RL/RON

• Transistors need to have fT > 50fo to operate well as a switching PA

• Efficiency drops rapidly when fT < 10fo – Dissipation during transitions becomes much more significant

[email protected] Earl McCune 10 Technology Similarities

• SM RF Power VERY important to carefully manage the switching duty cycle of the RF drive!

• Boost DC-DC

Earl McCune [email protected] Switching Supplies

• Switching supplies are not voltage sources

Inductor current • Energy is stored in both L and C Load current L R 2 C LD 112 VOUT 1 2 ELL= LI ⋅= L ⋅EC = CV ⋅ OUT 22RLD 2 SM PS c o n t r o l • Matching inductor current to load current requires a feedback controller – Loop dynamics constraint appears – Mis-match errors are all handled by the storage C

Earl McCune [email protected] 12 Switching Supply: Output Agility

Change from VO1 → VO2 1 L ∆ =∆ +∆ = +22 − E ELC E2 CV( OO21 V ) 2 RLD L = +C ∆⋅ V avg( V, V ) Greater the higher the 2 O OO21 output voltage is RLD (PROBLEM)

Fast switching voltage (within TSTEP):

∆EL∆⋅VO avg( V OO21, V ) Goes to infinity as the = + C TR2 T step time goes to zero STEP LD STEP (PROBLEM)

If the switching time gets very short, changing energy in the digital supply requires kilowatts of transient power Supply agility is therefore much slower than logic operating speeds

Earl McCune [email protected] Power Management Topic

• CPU power recovery (MicroNap / MicroWake) • LED drivers: Special capabilities • Direct (bridgeless) downconverting AC-DC + PFC • Duty cycle multiplier (digital)

Earl McCune [email protected] Solution: Hold the Energy for Later 50 microseconds per division

• Connect the load (or not) on command OFF ON OFF ON OFF • Example: 40 us OFF intervals – Load current is 17A for this measurement – 10 ns edge transition time on the device power supply • Spacing between and width of these OFF intervals is completely arbitrary Dynamic Power Supply Voltage waveform

Why we care: Inductor Keep C large for storage good regulation switch L

C DC input DC output

Synchronous Capacitor rectifier storage switch Earl McCune [email protected] Configurations

Normal Operation

Hold energy while OFF • Storing inductor current and electric charge within a DC-DC converter

• Linear regulators can also take advantage of this output filter (storage) switching

Earl McCune [email protected] Power Proportional Computing

• Input power is saved whenever Personal, Embedded Server region the output is not powered region – Input current falls as the output duty cycle is reduced, maintaining DC-DC conversion efficiency – ON time for this test is 200 microseconds • This regulator has an observed input bias current of 12 mA • Linear tracking is very good with duty cycle

Earl McCune [email protected] ACPI States

10 nanoseconds per transition • Nearly immediate transition between power states: no “friction” • Controlled by job scheduler • Optimum when applied to each core ACPI: C0 ACPI: C0 individually • Spacing between and width of these OFF intervals is completely arbitrary ACPI: C2 / C3

Scheduler

Assignments messages

Server cluster Responses

Earl McCune [email protected] Low Processing-Demand Case

Wide time view Zoom-in view

ON OFF ON OFF ON OFF ON OFF Control Command 1 A

Controlled Power Supply

• Energy is maintained within the power supply while the output is OFF • Turn-on edge here remains at 10 ns even after 2 milliseconds of OFF time – Output (20 us) pulse remains the same even when the OFF time exceeds 1 second (0.002% duty cycle) • No loss of processing throughput performance

Switch and Capacitor technology combine to set available ZPI hold time Inductor storage switch L

C Earl McCune [email protected] DC input DC output

Proving the ZPI Concept

• Modified existing DC-DC converter evaluation board – Additional control to the regulator – to manage internal energy storage • Applies more easily to linear regulators

• Nanosecond stop and start of amperes to the load is achieved – No overshoot on any transient

• Brings RF transmitter technology to power supplies for Computing

• US patents issued

Earl McCune [email protected] Power Management Topic

• CPU power recovery (MicroNap / MicroWake) • LED drivers: Special capabilities • Direct (bridgeless) downconverting AC-DC + PFC • Duty cycle frequency multiplier (digital)

Earl McCune [email protected] LED Dimming Method Options

Options for dimming already in production include • Shunt-switch pulsewidth modulation SS-PWM • Pulsewidth modulation PWM

• Linear Current Regulation IREG • Series Resistor (sense) RSNS And now a new method is added • Variable-resistance Var_R

Source DC-DC • Provide a widely varying resistor value in series with supply converter the LED current LED • Regulate the voltage across this resistor to a tiny DC-DC current value feedback • No flicker Error adjust + • Reduced EMI Digital • Adapts efficiently to LED VFWD dimming • Power dissipation is control LED_current * regulated voltage VREF ̶ (<50 mV) Vcontrol Dimming command Earl McCune [email protected] Comparison of Dimming Dynamic Range

Control Efficiency >98% Dimming Dynamic Range 100% 100% 90% 90% 80% 80% 70% 70% 60% 60% Var-R 50% Var-R 50% R_SNS 40% R_SNS 40% PWM 30% PWM 30% I_reg 20% DimmingControl Efficiency 20% I_reg DimmingControl Efficiency SS_PWM 10% SS_PWM 10% 0% 0% 0 0.2 0.4 0.6 0.8 1 0.00001 0.0001 0.001 0.01 0.1 1 Brightness (normalized) Brightness (normalized) 1/30,000

• Direct voltage or current control has limited dynamic range • Resistor dynamic range covers more than 10,000,000 : 1 – Hold voltage constant, vary resistance, and current must track [via Ohm’s Law] – LED dark current limits the actual useful range

Earl McCune [email protected] Control Efficiency and Flicker Performance

100.0%

99.5%

99.0%

HB white demonstrator ILED = constant

B&Y demonstrator 98.5% DimmingControl Efficiency HB red demonstrator

98.0% 0 10 20 30 40 50 60 Dimmer Control Setting

• LED current is tightly regulated in all cases, across 30,000 : 1 range • Actual dimming control efficiency is largely above 99% – And improves at higher brightness

Earl McCune [email protected] Power Management Topic

• CPU power recovery (MicroNap / MicroWake) • LED drivers: Special capabilities • Direct (bridgeless) downconverting AC-DC + PFC • Duty cycle frequency multiplier (digital)

Earl McCune [email protected] New AC-DC Solution

“Direct PFC” is a much simpler Direct PFC approach • bridge is eliminated • Power factor correction (PFC) happens using buck converter action • Low output voltage greatly simplifies any following DC-DC conversion • Operate at high frequency (1- 10 MHz) for small size

Earl McCune [email protected] Bridgeless AC-DC: Step 1

• The electric utility is not a differential signal • Combine two DCDC designs – Unipolar DCDC: +V in to +V out – Inverting DCDC: -V in to +V out • Operate these separate configurations on opposite signs of the input AC power

Earl McCune [email protected] Bridgeless AC-DC: Step 2

D = duty cycle of DCDC

• Combine these structures to use the same inductor • Operate these switches at HF - VHF to greatly shrink the inductor size • 4 FET switches perform rectification, PFC, and voltage downconversion – Diode bridge is eliminated – High voltage is eliminated • Line load is resistive even in the presence of phase-cut dimming • EMI filtering is greatly reduced

Earl McCune [email protected] Power Factor Correction

10,000.0

1,000.0

100.0

10.0

1.0 Effective Resistance (ohms) 0.1 Input Current (A) Input Power (W) 0.0 10000 100000 1000000 10000000 100000000 Switching Frequency (Hz) • Switching duty cycle sets the voltage transfer ratio

• Switching frequency varies the effective input impedance

Earl McCune [email protected] Summary

• We all share the same physics! • RF power switch technology does apply to power management • Recent progress – ZPI supply, switching 10’s of amperes in 10 nanoseconds or less • No dynamic controller settling transient • Prefers large output capacitance, excellent regulation – >30,000:1 no-flicker dimming • 98%+ control efficiency • Adaptive to LED color – No-bridge switching rectifier for AC-DC applications • Lower loss, easier EMI filtering • Adapting frequency provides PFC

Earl McCune [email protected] Abstract

Switching amperes of current in fractions of a nanosecond is regular practice in modern switch-based radio transmitter design. Switching power supplies presently achieve efficiencies that radio transmitter designers cannot even imagine. Mixing these technology bases leads to some interesting new potential product features, including nanosecond speed DC-DC output transitions without overshoot for 10’s of amperes, LED drivers with no flicker, dimming control exceeding 30,000:1 and 98% control efficiency, and elimination of bridge rectifier losses for AC-DC converters to name a few. This talk explores this combined technological territory. This talk will cover the following topics: • State of the art in switch-based radio transmitters • Common physics among switch-based and switching power converters • Preliminary theory and results from measurements on combined technology experiments • http://ewh.ieee.org/r6/scv/pels/

Earl McCune [email protected]