Design of Microwave Low-Noise Amplifiers in a Sige Bicmos Process
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Cascode Amplifiers by Dennis L. Feucht Two-Transistor Combinations
Cascode Amplifiers by Dennis L. Feucht Two-transistor combinations, such as the Darlington configuration, provide advantages over single-transistor amplifier stages. Another two-transistor combination in the analog designer's circuit library combines a common-emitter (CE) input configuration with a common-base (CB) output. This article presents the design equations for the basic cascode amplifier and then offers other useful variations. (FETs instead of BJTs can also be used to form cascode amplifiers.) Together, the two transistors overcome some of the performance limitations of either the CE or CB configurations. Basic Cascode Stage The basic cascode amplifier consists of an input common-emitter (CE) configuration driving an output common-base (CB), as shown above. The voltage gain is, by the transresistance method, the ratio of the resistance across which the output voltage is developed by the common input-output loop current over the resistance across which the input voltage generates that current, modified by the α current losses in the transistors: v R A = out = −α ⋅α ⋅ L v 1 2 β + + + vin RB /( 1 1) re1 RE where re1 is Q1 dynamic emitter resistance. This gain is identical for a CE amplifier except for the additional α2 loss of Q2. The advantage of the cascode is that when the output resistance, ro, of Q2 is included, the CB incremental output resistance is higher than for the CE. For a bipolar junction transistor (BJT), this may be insignificant at low frequencies. The CB isolates the collector-base capacitance, Cbc (or Cµ of the hybrid-π BJT model), from the input by returning it to a dynamic ground at VB. -
Experiment No. 7 - BJT Amplifier Input/Output Impedances
UNIVERSITY OF NORTH CAROLINA AT CHARLOTTE Department of Electrical and Computer Engineering Experiment No. 7 - BJT Amplifier Input/Output Impedances Overview: The purpose of this lab is to familiarize the student with the measurement of the input and output impedances of a Bipolar Junction Transistor single-stage amplifier. In previous experiments the DC biasing and AC amplification in BJT amplifiers has been investigated. This BJT experiment will build upon these previous experiments as well as expand into the investigation of input and output impedances. The amplifier chosen for study is the common-emmitter type as shown in Figure 1. Techniques for properly biasing the BJT amplifier and setting up AC amplification will be further utilized and methods for measuring imput and output impedances will be introduced. While the input impedance of an amplifier is in general a complex quantity, in the midband range it is predominantly resistive. Input impedance is defined as the ratio of imput voltage to input current. It is calculated from the AC equivalent circuit as the equivalent resistance looking into the input with all current cources replaced by an open and all voltage sources replaced by a short. The significance of input impedance is that it provides a measure of the loading effect of the amplifier. A low input impedance translates to a poor low-frequency response and a large input power requirement. For example, Op-Amps have a very large input impedance, and therefore, a good low- frequency response and a low input power requirement. Likewise, output impedance is in general a complex quantity, but is predominantly resistive in the midband range. -
Practical Issues of Using Negative Impedance Circuits As an Antenna Matching Element
Practical Issues of Using Negative Impedance Circuits as an Antenna Matching Element by Fu Tian Wong B.E. (Electrical & Electronic, First Class Honours), The University of Adelaide, Australia, 2011 Thesis submitted for the degree of Master of Engineering Science In School of Electrical and Electronic Engineering The University of Adelaide, Australia June 2011 Copyright © 2011 by Fu Tian Wong All Rights Reserved Contents Contents ............................................................................................................................. i Abstract ............................................................................................................................ iii Statement of Originality .................................................................................................... v Acknowledgments ........................................................................................................... vii Thesis Conventions .......................................................................................................... ix List of Figures .................................................................................................................. xi List of Tables.................................................................................................................. xiii 1 Introduction and Motivation ..................................................................................... 2 1.1 Introduction ....................................................................................................... -
Analysis of Electric Guitar Pickups
Analysis of Electric Guitar Pickups Fanuel T. Ban - Graduate Student, Penn State University / Sales Executive, LMS North America. 15061 Springdale St, Suite 102. Huntington Beach, CA 92649 Nomenclature ε = Electromagnetic Force f = Frequency Φ = Magnetic Flux L = Length B = Magnetic Induction f = Fundamental Frequency 1 A = Area fn = nth Harmonic c = Transverse Wave Speed A = Complex Amplitude of nth Solution n x = Displacement, x − Direction L = Pluck Location d y = Displacement, y − Direction h = Height t = Time n = Mode Number T = Tension L = Lumped Capacitance ρL = Linear Mass Density Zc = Complex Impedance j = Square Root of −1 Lcoil = Coil Lumped Inductance ω = Angular Frequency Ccoil = Coil Capacitance k = Wave Number C = Load Capacitance λ = Wavelength load Abstract Many guitarists do not understand how tones are generated by electromagnetic pickups on electric guitars. With further engineering insight, they may become more effective at achieving their desired tone. The creation of a tone - from a plucked string to the sound that emerges from the amplifier - requires the understanding of several strongly-interacting acoustical, mechanical, and electronic systems. These include the theory of electromagnetic induction, the design and fabrication of the pickup, and the location of the pickup relative to the bridge, the structural characteristics of the guitar, and the relationship of the pickup's output impedance to that of the instrument cable and guitar preamplifier. A complete analysis of the three most common electromagnetic pickups, the Single Coil, the Humbucker, and the P-90, used on the Fender Telecaster(TM) and Stratocaster(TM) and Gibson Les Paul(TM), provide examples for the approach developed in this paper. -
Using Fully Differential Amplifiers to Optimize High Speed Signal Chain Interfaces Agenda
Using fully differential amplifiers to optimize high speed signal chain interfaces Agenda • What is a fully differential amplifier (FDA)? • Solving interface challenges using an FDA – Overcoming challenges of balun – Level shifting using the FDA – Optimizing stability of FDA for low gain – Buffering a clock source using FDA – DAC buffering to drive single-ended load • Summary • Q/A (15min) What is a fully differential amplifier (FDA)? • Processes the difference voltage between its two inputs converting differential input to differential output • Converts single-ended input to differential output • FDA’s output common mode voltage can be controlled independently of the differential voltage via the VOCM pin Inside a typical FDA • Integrated fully-differential high AOL amplifier • Integrated wide-bandwidth, common- mode feedback, error amplifier • Integrated resistors to detect the average output common-mode voltage • Integrated mid-supply, common mode set resistors Differential signaling benefits • Higher output voltage swing for a given power rail • Increased immunity to noise as any signal common to both inputs is cancelled • Lower even-order harmonics with differential signaling Three rules governing FDA operation The voltage at the input nodes to the amplifier track The two outputs are 180° out of phase each other exactly (virtual short across inputs) The two outputs have the same DC offset voltage equal to VOCM FDA common mode voltages VID- = -VID+ = 0.2 VPP VID±_CM = 0 V VOCM = 2.5 V FDA differential voltages VID- = -VID+ = 0.2 VPP -
Impedance Matching and Smith Charts
Impedance Matching and Smith Charts John Staples, LBNL Impedance of a Coaxial Transmission Line A pulse generator with an internal impedance of R launches a pulse down an infinitely long coaxial transmission line. Even though the transmission line itself has no ohmic resistance, a definite current I is measured passing into the line by during the period of the pulse with voltage V. The impedance of the coaxial line Z0 is defined by Z0 = V / I. The impedance of a coaxial transmission line is determined by the ratio of the electric field E between the outer and inner conductor, and the induced magnetic induction H by the current in the conductors. 1 D D The surge impedance is, Z = 0 ln = 60ln 0 2 0 d d where D is the diameter of the outer conductor, and d is the diameter of the inner conductor. For 50 ohm air-dielectric, D/d = 2.3. Z = 0 = 377 ohms is the impedance of free space. 0 0 Velocity of Propagation in a Coaxial Transmission Line Typically, a coaxial cable will have a dielectric with relative dielectric constant er between the inner and outer conductor, where er = 1 for vacuum, and er = 2.29 for a typical polyethylene-insulated cable. The characteristic impedance of a coaxial cable with a dielectric is then 1 D Z = 60 ln 0 d r c and the propagation velocity of a wave is, v p = where c is the speed of light r In free space, the wavelength of a wave with frequency f is 1 c free−space coax = = r f r For a polyethylene-insulated coaxial cable, the propagation velocity is roughly 2/3 the speed of light. -
Lecture 5: Transmission Line Impedance Matching
EECS 117 Lecture 5: Transmission Line Impedance Matching Prof. Niknejad University of California, Berkeley University of California, Berkeley EECS 117 Lecture 5 – p. 1/20 Open Line I/V The open transmission line has infinite VSWR and ρL = 1. At any given point along the transmission line v(z) = V +(e−jβz + ejβz) = 2V + cos(βz) whereas the current is given by V + i(z) = (e−jβz ejβz) Z0 − or 2jV + i(z) = − sin(βz) Z0 University of California, Berkeley EECS 117 Lecture 5 – p. 2/20 Open Line Impedance (I) The impedance at any point along the line takes on a simple form v( ℓ) Zin( ℓ) = − = jZ0 cot(βℓ) − i( ℓ) − − This is a special case of the more general transmission line equation with ZL = . ∞ Note that the impedance is purely imaginary since an open lossless transmission line cannot dissipate any power. We have learned, though, that the line stores reactive energy in a distributed fashion. University of California, Berkeley EECS 117 Lecture 5 – p. 3/20 Open Line Impedance (II) A plot of the input impedance as a function of z is shown below Zin(λ/2) 10 8 6 ¯Zin(z)¯ ¯ ¯ ¯ Z0 ¯ ¯ ¯ 4 Zin(λ/4) 2 -1 -0.8 -0.6 z -0.4 -0.2 0 λ The cotangent function takes on zero values when βℓ approaches π/2 modulo 2π University of California, Berkeley EECS 117 Lecture 5 – p. 4/20 Open Line Impedance (III) Open transmission line can have zero input impedance! This is particularly surprising since the open load is in effect transformed from an open A plot of the voltage/current as a function of z is shown below i(−λ/4) v/v+ 2 1. -
Ultra High Input Impedance Electrometer/Pulse Train Converter for the Measurement of Beam Losses
Ultra High Input Impedance Electrometer/Pulse Train Converter For the Measurement of Beam Losses Daniel Schoo Version AD650.4 July 2013 1 DESIGN OVERVIEW The intended purpose of this project is to design a new circuit to measure beam losses in the NuMI, G-2 and Mu2e beamlines using traditional Andrew® Heliax® type HJ5-50 air dielectric cable based loss monitor detectors and report those values to the existing Radiation Safety System. Additionally the circuit may also be useful as a replacement for the obsolescent front end electronics in the Fermi “Chipmunk” radiation detector. This constrains the circuit to match the requirements of the existing system for measuring and reporting losses. Typically beam losses for radiation safety purposes are measured by collecting the electrical charge induced in a gas filled ion chamber exposed to the loss flux. The charge collected is directly proportional to the amount of beam loss. The value of the charge is then converted to a pulse train for reporting back to the Radiation Safety System. Because of the way that the Radiation Safety System evaluates the incoming data, the pulse train must possess two important characteristics. First, the peak frequency is proportional to the peak value of the collected charge. Second, the total number of pulses is proportional to the total integrated value of the charge. The pulse frequency immediately indicates the severity of the loss before the pulse count has completed in order to enable a rapid response to large losses. The pulse count reports the actual loss value. This is reported over a period of time limited by the rate that the Radiation Safety “MUX” data collection system can accept, which could be many seconds in duration for large losses. -
Input Impedance Analysis of Wearable Antenna and Experimental Study with Real Human Subjects: Differences Between Individual Users
electronics Article Input Impedance Analysis of Wearable Antenna and Experimental Study with Real Human Subjects: Differences between Individual Users Dairoku Muramatsu 1,* and Ken Sasaki 2 1 Research Institute for Science and Technology, Organization for Research Advancement, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan 2 Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan; [email protected] * Correspondence: [email protected]; Tel.: +81-4-7124-1501 Abstract: In human body communication (HBC) systems, radio-frequency signals are excited in the human body through a wearable antenna comprised of electrodes that are in contact with the surface of the body. The input impedance characteristics of these antennas are important design parameters for increasing transmission efficiency and reducing signal reflection, similar to other wireless circuits. In this study, we discuss variations of input impedance characteristics of a wearable antenna prototype caused by differences among real human subjects. A realistic human arm model is used for simulations, and the analytical results obtained are compared to measured data obtained from real human subjects, in a range from 1 to 100 MHz. The simulations of input impedance characteristics from antennas worn on the wrists of male and female models with dry and wet skin conditions show that the impedance variation between genders is small. The moisture condition of Citation: Muramatsu, D.; Sasaki, K. the skin has little influence on frequencies exceeding several MHz. Measurements with a proto-type Input Impedance Analysis of wearable antenna and 22 real human subjects reveal that HBC is robust against the variations of Wearable Antenna and Experimental individual users from the viewpoint of the voltage standing wave ratio. -
Basics of Operational Amplifiers and Comparators Application Note
Basics of Operational Amplifiers and Comparators Application Note Basics of Operational Amplifiers and Comparators Outline: Op-amps, also known as operational amplifiers, are used for voltage amplifiers, filters, phase shifts, and more. The comparator, also known as a voltage comparator, has a function to detect the high or low voltage with respect to the reference signal. This document explains the basic electrical characteristics (offset voltage, common-mode input voltage, open gain, common-mode input signal rejection ratio, frequency characteristics, etc.), absolute maximum ratings, and general usage (non-inverting amplifier, inverting amplifier). © 202 0-2021 1 2021-03-26 Toshiba Electronic Devices & Storage Corporation Basics of Operational Amplifiers and Comparators Application Note Table of Contents 1. Introduction ............................................................................................................. 3 2. Op-amps and comparators ......................................................................................... 4 2.1. Op-amp and comparator configurations.................................................................. 4 2.2. Selecting op-amps and comparators ...................................................................... 6 2.3. Power supplies for op-amps and comparators ......................................................... 6 2.4. Noninverting amplifier ......................................................................................... 7 2.5. Inverting amplifier ............................................................................................. -
Impedance Matching: a Primer
Jaycar Electronics Reference Data Sheet: IMPMATCH.PDF (1) IMPEDANCE MATCHING: A PRIMER From time to time youll come across the term impedance matching in various areas of electronics, and especially in fields like RF and audio engineering. However even in these fields its often misused, probably because many people dont really understand the concepts behind it. In this primer well try to clarify what impedance matching is really all about, why its important in some situations and not important in others. Textbooks usually explain the idea of impedance matching with a very simple example of an electrical generator feeding a resistive load, as shown in Fig.1. Because the generator has an internal resistance of its own (RG) as all real generators do this tends to dissipate some of the generators output power as heat, Fig.1: A generator driving a load resistance RL whenever we connect a load to its output terminals. So and its own internal resistance RG. the full mechanical power fed into the generator cant be drawn from it as electrical power, because some will impedance. And the idea of matching the load and always be wasted in R . G generator resistance became one of matching the source When early electrical engineers were faced with this and load impedance impedance matching. problem, they naturally enough did everything they Now this may sound simple and straightforward, but could to reduce the internal resistance of their its important to remember where the idea came from, generators. However they were inevitably still left with and also realise what exactly is going on when we do SOME internal resistance, because its impossible to match load and generator/source resistances or reduce the resistance to zero unless you run the impedances. -
Impedance Calculations
Revisiting a T-Line With Any Termination In the general case, where a transmission line is terminated in ZL, the impedance along the line is given by: j zZZL 0 j z j z j z e e e e ZZL 0 Z() z Z Z 0j z j z 0 e e j zZZL 0 j z e e ZZL 0 j z j z ZLL Z0 e Z Z 0 e ZL 2cos z Z0 2 j sin z ZZ0j z j z 0 ZZeLLL 0 ZZe 0 ZjzZ2 sin 0 2cos z ZL jZ0 tan z Z0 Note: Z(z)=Z0 if ZL=Z0 Z0 jZL tan z The above equation shows how the input impedance to an unmatched transmission line changes with electrical length, z. Since the electrical length changes with frequency, the input impedance to an unmatched line will be frequency dependent. Impedance Calculations Because the formula for impedance is a bit cumbersome and not intuitive, design calculations and measurements are often made graphicallyusing a Smith Chart. The Smith Chart works with normalized impedance and admittance, where normalization is made with respect to the characteristic impedance of the transmission line. For example, the normalized impedance for a load ZL = 73 + j42 on a 50 transmission line is ZLN = 1.46 + j0.84 By plotting the normalized load impedance on a Smith Chart, the input impedance as a function of line length can be found. The Smith Chart also provides the value of the reflection coefficient, power delivered to load, as well as the voltage standing wave ratio (VSWR) Distance measurements are given in terms of wavelengths.