Lecture

OTA Design: Small-signal Analysis

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In course

EE-520: Low-power analog IC design

This course presents the design of low-power analog CMOS integrated circuits. The techniques are based on the concept of inversion coefficient that can be used as the main design parameter for the optimization of figures-of-merit applied to circuits includ ...

Description

This lecture covers the design and analysis of Operational Transconductance Amplifiers (OTAs) and Operational Amplifiers (OPAMPs). It delves into topics such as OTA design principles, small-signal transfer functions, transfer function approximation, and settling time analysis. The lecture also explores concepts like differential cascode OTAs, capacitive feedback, and large-signal analysis. Various design techniques and compensation methods are discussed to ensure stability and performance in low-power analog IC design.

Instructor

Christian Enz

Christian C. Enz (M84, S'12) received the M.S. and Ph.D. degrees in Electrical Engineering from the EPFL in 1984 and 1989 respectively. From 1984 to 1989 he was research assistant at the EPFL, working in the field of micro-power analog IC design. In 1989 he was one of the founders of Smart Silicon Systems S.A. (S3), where he developed several low-noise and low-power ICs, mainly for high energy physics applications. From 1992 to 1997, he was an Assistant Professor at EPFL, working in the field of low-power analog CMOS and BiCMOS IC design and device modeling. From 1997 to 1999, he was Principal Senior Engineer at Conexant (formerly Rockwell Semiconductor Systems), Newport Beach, CA, where he was responsible for the modeling and characterization of MOS transistors for the design of RF CMOS circuits. In 1999, he joined the Swiss Center for Electronics and Microtechnology (CSEM) where he launched and lead the RF and Analog IC Design group. In 2000, he was promoted Vice President, heading the Microelectronics Department, which became the Integrated and Wireless Systems Division in 2009. He joined the EPFL as full professor in 2013, where he is currently the director of the Institute of Microengineering (IMT) and head of the Integrated Circuits Laboratory (ICLAB).He is lecturing and supervising undergraduate and graduate students in the field of Analog and RF IC Design at EPFL. His technical interests and expertise are in the field of very low-power analog and RF IC design, semiconductor device modeling, and inexact and error tolerant circuits and systems.He has published more than 200 scientific papers and has contributed to numerous conference presentations and advanced engineering courses. Together with E. Vittoz and F. Krummenacher he is one of the developer of the EKV MOS transistor model and the author of the book "Charge-Based MOS Transistor Modeling - The EKV Model for Low-Power and RF IC Design" (Wiley, 2006). He has been member of several technical program committees, including the International Solid-State Circuits Conference (ISSCC) and European Solid-State Circuits Conference (ESSCIRC). He has served as a vice-chair for the 2000 International Symposium on Low Power Electronics and Design (ISLPED), exhibit chair for the 2000 International Symposium on Circuits and Systems (ISCAS) and chair of the technical program committee for the 2006 European Solid-State Circuits Conference (ESSCIRC). Since 2012 he has been elected as member of the IEEE Solid-State Circuits Society (SSCS) Administrative Commmittee (AdCom). He is also Chair of the IEEE SSCS Chapter of Switzerland.

Official source

Ontological neighbourhood

Physics

Electromagnetism: Electrical networks

Related concepts (32)

Amplifier

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude (magnitude of the voltage or current) of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input.

Digital signal processing

Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are a sequence of numbers that represent samples of a continuous variable in a domain such as time, space, or frequency. In digital electronics, a digital signal is represented as a pulse train, which is typically generated by the switching of a transistor.

Cascode

The cascode is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage. Compared to a single amplifier stage, this combination may have one or more of the following characteristics: higher input–output isolation, higher input impedance, high output impedance, higher bandwidth. In modern circuits, the cascode is often constructed from two transistors (BJTs or FETs), with one operating as a common emitter or common source and the other as a common base or common gate.

Settling time

In control theory the settling time of a dynamical system such as an amplifier or other output device is the time elapsed from the application of an ideal instantaneous step input to the time at which the amplifier output has entered and remained within a specified error band. Settling time includes a propagation delay, plus the time required for the output to slew to the vicinity of the final value, recover from the overload condition associated with slew, and finally settle to within the specified error.

Small-signal model

Small-signal modeling is a common analysis technique in electronics engineering used to approximate the behavior of electronic circuits containing nonlinear devices with linear equations. It is applicable to electronic circuits in which the AC signals (i.e., the time-varying currents and voltages in the circuit) are small relative to the DC bias currents and voltages. A small-signal model is an AC equivalent circuit in which the nonlinear circuit elements are replaced by linear elements whose values are given by the first-order (linear) approximation of their characteristic curve near the bias point.

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Analog CMOS Integrated Circuits: Fundamentals

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Low-power Analog IC Design: Amplifiers