The Instrumentation Amplifier Handbook
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Chapter 10 Differential Amplifiers
Chapter 10 Differential Amplifiers 10.1 General Considerations 10.2 Bipolar Differential Pair 10.3 MOS Differential Pair 10.4 Cascode Differential Amplifiers 10.5 Common-Mode Rejection 10.6 Differential Pair with Active Load 1 Audio Amplifier Example An audio amplifier is constructed as above that takes a rectified AC voltage as its supply and amplifies an audio signal from a microphone. CH 10 Differential Amplifiers 2 “Humming” Noise in Audio Amplifier Example However, VCC contains a ripple from rectification that leaks to the output and is perceived as a “humming” noise by the user. CH 10 Differential Amplifiers 3 Supply Ripple Rejection vX Avvin vr vY vr vX vY Avvin Since both node X and Y contain the same ripple, their difference will be free of ripple. CH 10 Differential Amplifiers 4 Ripple-Free Differential Output Since the signal is taken as a difference between two nodes, an amplifier that senses differential signals is needed. CH 10 Differential Amplifiers 5 Common Inputs to Differential Amplifier vX Avvin vr vY Avvin vr vX vY 0 Signals cannot be applied in phase to the inputs of a differential amplifier, since the outputs will also be in phase, producing zero differential output. CH 10 Differential Amplifiers 6 Differential Inputs to Differential Amplifier vX Avvin vr vY Avvin vr vX vY 2Avvin When the inputs are applied differentially, the outputs are 180° out of phase; enhancing each other when sensed differentially. CH 10 Differential Amplifiers 7 Differential Signals A pair of differential signals can be generated, among other ways, by a transformer. -
Techniques for Low Power Analog, Digital and Mixed Signal CMOS
Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2005 Techniques for low power analog, digital and mixed signal CMOS integrated circuit design Chuang Zhang Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Electrical and Computer Engineering Commons Recommended Citation Zhang, Chuang, "Techniques for low power analog, digital and mixed signal CMOS integrated circuit design" (2005). LSU Doctoral Dissertations. 852. https://digitalcommons.lsu.edu/gradschool_dissertations/852 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. TECHNIQUES FOR LOW POWER ANALOG, DIGITAL AND MIXED SIGNAL CMOS INTEGRATED CIRCUIT DESIGN A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Electrical and Computer Engineering by Chuang Zhang B.S., Tsinghua University, Beijing, China. 1997 M.S., University of Southern California, Los Angeles, U.S.A. 1999 M.S., Louisiana State University, Baton Rouge, U.S.A. 2001 May 2005 ACKNOWLEDGEMENTS I would like to dedicate my work to my parents, Mr. Jinquan Zhang and Mrs. Lingyi Yu and my wife Yiqian Wang, for their constant encouragement throughout my life. I am very grateful to my advisor Dr. Ashok Srivastava for his guidance, patience and understanding throughout this work. -
Differential Amplifiers
www.getmyuni.com Operational Amplifiers: The operational amplifier is a direct-coupled high gain amplifier usable from 0 to over 1MH Z to which feedback is added to control its overall response characteristic i.e. gain and bandwidth. The op-amp exhibits the gain down to zero frequency. Such direct coupled (dc) amplifiers do not use blocking (coupling and by pass) capacitors since these would reduce the amplification to zero at zero frequency. Large by pass capacitors may be used but it is not possible to fabricate large capacitors on a IC chip. The capacitors fabricated are usually less than 20 pf. Transistor, diodes and resistors are also fabricated on the same chip. Differential Amplifiers: Differential amplifier is a basic building block of an op-amp. The function of a differential amplifier is to amplify the difference between two input signals. How the differential amplifier is developed? Let us consider two emitter-biased circuits as shown in fig. 1. Fig. 1 The two transistors Q1 and Q2 have identical characteristics. The resistances of the circuits are equal, i.e. RE1 = R E2, RC1 = R C2 and the magnitude of +VCC is equal to the magnitude of �VEE. These voltages are measured with respect to ground. To make a differential amplifier, the two circuits are connected as shown in fig. 1. The two +VCC and �VEE supply terminals are made common because they are same. The two emitters are also connected and the parallel combination of RE1 and RE2 is replaced by a resistance RE. The two input signals v1 & v2 are applied at the base of Q1 and at the base of Q2. -
Review of CMOS Amplifiers for High Frequency Applications
International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249-8958 (Online), Volume-10 Issue-2, December 2020 Review of CMOS Amplifiers for High Frequency Applications Sajin. C.S, T. A. Shahul Hameed Abstract: The headway in electronics technology proffers Block diagram of an RF communication system is shown in user-friendly devices. The characteristics such as high Fig.1. In RF communication, amplifier circuits such as low integration, low power consumption, good noise immunity are the noise amplifier, power amplifier, distributed amplifier and significant benefits that CMOS offer, paying many challenges driver amplifier play a vital role. Now days a lot of research simultaneously with it. The short channel effects and presence of parasitic which prevent speed pose questions on the performance works being done in power amplifier and low noise amplifier. parameters. A great sort of works has done by many groups in the While designing a CMOS amplifier many points have to be design of the CMOS amplifier for high-frequency applications to noted to avoid unnecessary performance degradation. CMOS discuss the parameters such as power consumption, high technology has very low power consumption so it can be used bandwidth, high speed and linearity trade-off to obtain an for this low power invented amplifier. CMOS is a MOSFET optimized output. A lot of amplifier topologies are experimented that has symmetrical and complementary pair of p and n-type and discussed in the literature with its design and simulation. In this paper, the various efforts associated with CMOS amplifier MOSFET. The designer should deal with numerous tradeoffs circuit for high-frequency applications are studying extensively. -
(12) United States Patent (10) Patent No.: US 6,356,152 B1 Jezdic Et Al
USOO6356152B1 (12) United States Patent (10) Patent No.: US 6,356,152 B1 Jezdic et al. (45) Date of Patent: Mar. 12, 2002 (54) AMPLIFIER WITH FOLDED SUPER- 5,451.901 A 9/1995 Welland ..................... 330/133 FOLLOWERS 5,512.858 A 4/1996 Perrot ........................ 330/258 5,578,964 A 11/1996 Kim et al. .................. 330/258 (75) Inventors: Andrija Jezdic, Arlington; John L. St.2Y- 2 A : 3.0. S.Inser el G.al. O.. : Wateriority is) 6,118,340 A 9/2000 Koen ......................... 330/253 (73) Assignee: Texas Instruments Incorporated, * cited by examiner Dallas, TX (US) (*) Notice: Subject to any disclaimer, the term of this Primary 'EC, R, Pascal patent is extended or adjusted under 35 ASSistant Examiner Khan Van Nguyen U.S.C. 154(b) by 0 days (74) Attorney, Agent, or Firm-Pedro P. Hernandez; W. a -- James Brady, III; Frederick J. Telecky, Jr. (21) Appl. No.: 09/617,069 (57) ABSTRACT (22) Filed: Jul. 16, 2000 Fixed gain amplifiers have particular use in the read channel of hard disk drives. ACMOS fixed gain amplifier 18c having Related U.S. Application Data a constant gain over the large dynamic range of hard disk (60) Provisional application No. 60/143,798, filed on Jul. 14, drive applications is provided by incorporating Super fol 1999. lower transistors M3 and M4 into the input stage of the fixed (51) Int. Cl. .................................................. HO3F 3/45 gain amplifier. The Super follower transistors are folded into (52) U.S. Cl. ........................................ 330/253; 330/258 the output stage of the amplifier. The differential current (58) Field of Search ................................ -
621 212 Electronics and Communication Engineering Ec6304/Linear Integrated Circuits
DSEC/ECE/EC6304-LIC/QB 1 DHANALAKSHMI SRINIVASAN ENGINEERING COLLEGE -621 212 ELECTRONICS AND COMMUNICATION ENGINEERING EC6304/LINEAR INTEGRATED CIRCUITS QUESTION BANK UNIT 1(2 MARKS) 1. What is an integrated circuit? APRIL/MAY 2010 An integrated circuit (IC) is a miniature, low cost electronic circuit consisting of active and Passive components fabricated together on a single crystal of silicon. The active components are Transistors and diodes and passive components are resistors and capacitors. 2. What is current mirror? APRIL/MAY 2010 A constant current source (current mirror) makes use of the fact that for a transistor in the active mode of operation, the collector current is relatively independent of the collector voltage 3. What are two requirements to be met for a good current source? MAY/JUNE 2012 a. Superior insensitivity of circuit performance to power supply variations and temperature. b. More economical than resistors in terms of die area required providing bias currents of small value. c. When used as load element, the high incremental resistance of current source results in high voltage gains at low supply voltages. 4. What are all the important characteristics of ideal op-amp? APRIL/MAY 2015 Ideal characteristics of OPAMP 1. Open loop gain infinite 2. Input impedance infinite 3. Output impedance low 4. Bandwidth infinite 5. Zero offset, ie, Vo=0 when V1=V2=0 5. Define CMRR of OP-AMP APRIL/MAY 2011 The relative sensitivity of an op-amp to a difference signal as compared to a common - mode signal is called the common -mode rejection ratio. It is expressed in decibels. -
Fully-Differential Amplifiers
Application Report S Fully-Differential Amplifiers James Karki AAP Precision Analog ABSTRACT Differential signaling has been commonly used in audio, data transmission, and telephone systems for many years because of its inherent resistance to external noise sources. Today, differential signaling is becoming popular in high-speed data acquisition, where the ADC’s inputs are differential and a differential amplifier is needed to properly drive them. Two other advantages of differential signaling are reduced even-order harmonics and increased dynamic range. This report focuses on integrated, fully-differential amplifiers, their inherent advantages, and their proper use. It is presented in three parts: 1) Fully-differential amplifier architecture and the similarities and differences from standard operational amplifiers, their voltage definitions, and basic signal conditioning circuits; 2) Circuit analysis (including noise analysis), provides a deeper understanding of circuit operation, enabling the designer to go beyond the basics; 3) Various application circuits for interfacing to differential ADC inputs, antialias filtering, and driving transmission lines. Contents 1 Introduction . 3 2 What Is an Integrated, Fully-Differential Amplifier? . 3 3 Voltage Definitions . 5 4 Increased Noise Immunity . 5 5 Increased Output Voltage Swing . 6 6 Reduced Even-Order Harmonic Distortion . 6 7 Basic Circuits . 6 8 Circuit Analysis and Block Diagram . 8 9 Noise Analysis . 13 10 Application Circuits . 15 11 Terminating the Input Source . 15 12 Active Antialias Filtering . 20 13 VOCM and ADC Reference and Input Common-Mode Voltages . 23 14 Power Supply Bypass . 25 15 Layout Considerations . 25 16 Using Positive Feedback to Provide Active Termination . 25 17 Conclusion . 27 1 SLOA054E List of Figures 1 Integrated Fully-Differential Amplifier vs Standard Operational Amplifier. -
Mosfet Differential Amplifier (Two-Week Lab)
page 1 of 7 MOSFET DIFFERENTIAL AMPLIFIER (TWO-WEEK LAB) BACKGROUND The MOSFET is by far the most widely used transistor in both digital and analog circuits, and it is the backbone of modern electronics. One of the most common uses of the MOSFET in analog circuits is the construction of differential amplifiers. The latter are used as input stages in op-amps, video amplifiers, high-speed comparators, and many other analog-based circuits. MOSFET differential amplifiers are used in integrated circuits, such as operational amplifiers, they provide a high input impedance for the input terminals. A properly designed differential amplifier with its current-mirror biasing stages is made from matched-pair devices to minimize imbalances from one side of the differential amplifier to the other. In this lab, you will design a differential amplifier by first verifying its operation in PSPICE, then building and testing your circuit stage by stage. In your lab kit, you will find one or more CD4007 integrated circuits. (The letter prefix may vary; it's the number 4007 that matters.) This IC contains a number of NMOS and PMOS devices, as shown below. You may assume that all the NMOS transistors are matched to each other (same value of K and threshold voltage VTR), and that all the PMOS devices are similarly matched to each other. Use the devices in this integrated circuit when building your differential amplifier, as requested in Levels 2 and 3. page 2 of 7 BACKGROUND The general topology of a differential amplifier is shown below. Two active devices are connected to a positive voltage supply via passive series elements. -
Lsk389 Application Note Dual Monolithic Jfet for Ultra-Low Noise Applications
Over 30 Years of Quality Through Innovation LSK389 APPLICATION NOTE DUAL MONOLITHIC JFET FOR ULTRA-LOW NOISE APPLICATIONS By: Bob Cordell 01/21/2020 REV. A3 Linear Integrated Systems • 4042 Clipper Court • Fremont, CA 94538 • Tel: 510 490-9160 • Fax: 510 353-0261 • Email: [email protected] LINEAR SYSTEMS LSK389 DUAL MONOLITHIC JFET FOR ULTRA-LOW NOISE APPLICATIONS Features Applications ▪ Low Wideband Noise ▪ Low Noise Amplifiers ▪ Low 1/f Noise ▪ Differential Amplifiers ▪ High Transconductance ▪ High Input Impedance Amplifiers ▪ Well-Matched Threshold Voltages ▪ Phono and Other Audio Preamps ▪ High gm/Capacitance Ratio ▪ Condenser Microphone Preamps ▪ Industry's First 100% Noise-Tested JFET ▪ Electrometers ▪ Piezoelectric Sensor Preamps ▪ Front-end for Low-Noise Op Amps Introduction The LSK389 is the industry’s lowest noise Dual N-Channel JFET, 100% tested, guaranteed to meet 1/f and broadband noise specifications, while eliminating burst (RTN or popcorn) noise entirely. The product displays high transconductance and very good matching. It is the JFET of choice for low noise applications, especially those requiring a differential amplifier input stage. LSK389 Key Specifications ▪ 1.3 nV/√Hz input noise at 1 kHz, ID = 2 mA ▪ 1.5 nV/√Hz at 10 Hz, ID = 2 mA ▪ 14 mS transconductance at ID = 2 mA ▪ Improved DC offset ±15 mV max. ▪ CISS = 25 pF typ. ▪ CRSS = 5.5 pF typ. ▪ Breakdown voltage = 40 V min. ▪ 4 grades of IDSS available (A, B, C, D) N-Channel JFET Basics The simplified equation below describes the DC operation of a JFET [1]. The term Vt is the threshold voltage. The term is the transconductance coefficient of the JFET (not to be confused with BJT current gain). -
Fully Differential Op Amps Made Easy
Application Report SLOA099 - May 2002 Fully Differential Op Amps Made Easy Bruce Carter High Performance Linear ABSTRACT Fully differential op amps may be unfamiliar to some designers. This application report gives designers the essential information to get a fully differential design up and running. Contents 1 Introduction . 2 2 What Does Fully Differential Mean?. 2 3 How Is the Second Output Used?. 3 3.1 Differential Gain Stages. 3 3.2 Single-Ended to Differential Conversion. 4 3.3 Working With Terminated Inputs. 5 4 A New Function . 7 5 Conclusions . 8 6 References . 9 List of Figures 1 Single-Ended Op Amp Schematic Symbol. 2 2 Fully Differential Op Amp Schematic Symbol. 2 3 Closing the Loop on a Single-Ended Op Amp. 3 4 Closing the Loop on a Fully Differential Op Amp. 3 5 Single Ended to Differential Conversion. 4 6 Relationship Between Vin, Vout+, and Vout– . 5 7 Fully Differential Amplifier Component Calculator. 6 8 Using a Fully Differential Op Amp to Drive an ADC. 7 9 Effect of Vocm on Vout+ and Vout– . 8 1 SLOA099 1 Introduction Fully differential op amps may be intimidating to some designers, But op amps began as fully differential components over 50 years ago. Techniques about how to use the fully differential versions have been almost lost over the decades. However, today’s fully differential op amps offer performance advantages unheard of in those first units. This report does not attempt a detailed analysis of op amp theory; reference 1 covers theory well. Instead, this report presents just the facts a designer needs to get started, and some resources for further design assistance. -
Transistors 101
Nanotechnology 101 Series Transistors 101 Mark Lundstrom Purdue University Network for Computational Nanotechnology West Lafayette, IN USA NCN www.nanohub.org 1 what to transistors do? 2 Field-Effect Transistor Lillienfield, 1925 Heil, 1935 Bardeen, Schockley, and Brattain, 1947 “The transistor was probably the most important invention of the 20th century,” Ira Flatow, Transistorized! www.pbs.org/transistor 3 transistors integrated circuit Intel 4004 Kilby and Noyce (1958, 1959) Hoff (1971) • junction transistor, 1951 • commercial IC’s, 1961 • silicon BJT, 1954 • PMOS IC’s, 1963 ~2000 transistors • MOSFET, 1960 • CMOS invented, 1963 • NMOS IC’s, 1970 4 silicon microelectronics Silicon wafer (300 mm) Silicon “chip” (~ 2 cm x 2 cm) MPU ROM DSP Control logic RAM analog Intel TI cell phone chip 5 Transistor scaling ~ L Each technology generation: (scaling) L " L 2 A " A 2 Number of transistors per chip doubles (Moore’s Law) ! ! 6 Moore’s Law http://public.itrs.net/ > - - ) > - 10 10000 s - r ) e s t n e o r m c o i 1 1000 n m a ( n ( e z e i z s i s e 0.1 100 r e u r t u a t e nanoelectronics a F 0.01 10 e F 70 80 90 00 10 20 Year--> L = 6 nm (IBM, 2002) L = 5 nm (NEC, 20703) applications symbol switch amplifier D D D G G G S S S 8 EE fundamentals 1) Voltage 2) Current 3) Resistance 4) I-V characteristics resistor voltage source current source 5) Metals, insulators, and semiconductors 9 voltage potential energy = mgh h FG ground 10 voltage + + + + + + + + + + + + + + ++ V = E d Volts d electric field, E force F = qE - - - - - - - - - - - -
The Differential Amplifier
The Differential amplifier - An Intuitive Look We will now take a look at a very versatile amplifier circuit called the differential amplifier. This amplifier is at the heart of many analog integrated circuits. We will look at the circuit only close enough to get a good intuitive feel for how it works and what it can do. Vcc rc1 rc2 1K 1K Q1 Q2 rb1 Vc1 Vc2 rb2 + + Vin1 Vin2 - - 5mA The Differential Amplifier The differential amplifier operates by amplifying the difference between two separate inputs. These inputs are marked above as Vin1 and Vin2. Note that the amplifier is symmetrical about a center line going through the 5ma current source. For the sake of this explanation, we will consider the 5mA current source to be “not quite” ideal. In this case, it means that the current source is only able to drive its upper terminal to zero volts when attempting to force a mini- mum of 5mA to flow to ground. However, it will never allow more than 5mA to flow no matter how much base current is forced into Q1 andQ2. To understand the operation of the amplifier, we will assume that Vin1 and Vin2 are equal in magnitude. Within the operating region for the amplifier, this will cause equal base and emit- ter currents to flow through each transistor. Since the current source will not allow more than 5mA of current to flow, the current through rc1 and rc2 will be exactly 2.5ma. This causes a potential of 2.5 volts to appear at Vc1 and Vc2.