Design of Low-Voltage, Low-Power CMOS Operational Amplifier Cells describes the theory and design of the circuit elements that are required to realize a low-voltage, low-power operational amplifier. These elements include constant-gm rail-to-rail input stages, class-AB rail-to-rail output stages and frequency compensation methods. Several examples of each of these circuit elements are investigated. Furthermore, the book illustrates several silicon realizations, giving their measurement results. The text focuses on compact low-voltage low-power operational amplifiers with good performance. Six simple high-performance class-AB amplifiers are realized using a very compact topology making them particularly suitable for use as VLSI library cells. All of the designs can use a supply voltage as low as 3V. One of the amplifier designs dissipates only 50μW with a unity gain frequency of 1.5 MHz. A second set of amplifiers run on a supply voltage slightly above 1V. The amplifiers combine a low power consumption with a gain of 120 dB. In addition, the design of three fully differential operational amplifiers is addressed. Design of Low-Voltage, Low-Power CMOS Operational Amplifier Cells is intended for professional designers of analog circuits. It is also suitable for use as a text book for an advanced course in CMOS operational amplifier design.

Oversampling techniques based on sigma-delta modulation are widely used to implement the analog/digital interfaces in CMOS VLSI technologies. This approach is relatively insensitive to imperfections in the manufacturing process and offers numerous advantages for the realization of high-resolution analog-to-digital (A/D) converters in the low-voltage environment that is increasingly demanded by advanced VLSI technologies and by portable electronic systems. In The Design of Low-Voltage, Low-Power Sigma-Delta Modulators, an analysis of power dissipation in sigma-delta modulators is presented, and a low-voltage implementation of a digital-audio performance A/D converter based on the results of this analysis is described. Although significant power savings can typically be achieved in digital circuits by reducing the power supply voltage, the power dissipation in analog circuits actually tends to increase with decreasing supply voltages. Oversampling architectures are a potentially power-efficient means of implementing high-resolution A/D converters because they reduce the number and complexity of the analog circuits in comparison with Nyquist-rate converters. In fact, it is shown that the power dissipation of a sigma-delta modulator can approach that of a single integrator with the resolution and bandwidth required for a given application. In this research the influence of various parameters on the power dissipation of the modulator has been evaluated and strategies for the design of a power-efficient implementation have been identified. The Design of Low-Voltage, Low-Power Sigma-Delta Modulators begins with an overview of A/D conversion, emphasizing sigma-delta modulators. It includes a detailed analysis of noise in sigma-delta modulators, analyzes power dissipation in integrator circuits, and addresses practical issues in the circuit design and testing of a high-resolution modulator. The Design of Low-Voltage, Low-Power Sigma-Delta Modulators will be of interest to practicing engineers and researchers in the areas of mixed-signal and analog integrated circuit design.

Design of Low-Voltage Low-Power CMOS Delta-Sigma A/D Converters investigates the feasibility of designing Delta-Sigma Analog to Digital Converters for very low supply voltage (lower than 1.5V) and low power operation in standard CMOS processes. The chosen technique of implementation is the Switched Opamp Technique which provides Switched Capacitor operation at low supply voltage without the need to apply voltage multipliers or low VtMOST devices. A method of implementing the classic single loop and cascaded Delta-Sigma modulator topologies with half delay integrators is presented. Those topologies are studied in order to find the parameters that maximise the performance in terms of peak SNR. Based on a linear model, the performance degradations of higher order single loop and cascaded modulators, compared to a hypothetical ideal modulator, are quantified. An overview of low voltage Switched Capacitor design techniques, such as the use of voltage multipliers, low VtMOST devices and the Switched Opamp Technique, is given. An in-depth discussion of the present status of the Switched Opamp Technique covers the single-ended Original Switched Opamp Technique, the Modified Switched Opamp Technique, which allows lower supply voltage operation, and differential implementation including common mode control techniques. The restrictions imposed on the analog circuits by low supply voltage operation are investigated. Several low voltage circuit building blocks, some of which are new, are discussed. A new low voltage class AB OTA, especially suited for differential Switched Opamp applications, together with a common mode feedback amplifier and a comparator are presented and analyzed. As part of a systematic top-down design approach, the non-ideal charge transfer of the Switched Opamp integrator cell is modeled, based upon several models of the main opamp non-ideal characteristics. Behavioral simulations carried out with these models yield the required opamp specifications that ensure that the intended performance is met in an implementation. A power consumption analysis is performed. The influence of all design parameters, especially the low power supply voltage, is highlighted. Design guidelines towards low power operation are distilled. Two implementations are presented together with measurement results. The first one is a single-ended implementation of a Delta-Sigma ADC operating with 1.5V supply voltage and consuming 100 &mgr;W for a 74 dB dynamic range in a 3.4 kHz bandwidth. The second implementation is differential and operates with 900 mV. It achieves 77 dB dynamic range in 16 kHz bandwidth and consumes 40 &mgr;W. Design of Low-Voltage Low-Power CMOS Delta-Sigma A/D Converters is essential reading for analog design engineers and researchers.

Operational Amplifiers – Theory and Design, Second Edition presents a systematic circuit design of operational amplifiers. Containing state-of-the-art material as well as the essentials, the book is written to appeal to both the circuit designer and the system designer. It is shown that the topology of all operational amplifiers can be divided into nine main overall configurations. These configurations range from one gain stage up to four or more stages. Many famous designs are evaluated in depth. Additional chapters included are on systematic design of μV-offset operational amplifiers and precision instrumentation amplifiers by applying chopping, auto-zeroing, and dynamic element-matching techniques. Also, techniques for frequency compensation of amplifiers with high capacitive loads have been added. Operational Amplifiers – Theory and Design, Second Edition presents high-frequency compensation techniques to HF-stabilize all nine configurations. Special emphasis is placed on low-power low-voltage architectures with rail-to-rail input and output ranges. In addition to presenting characterization of operational amplifiers by macro models and error matrices, together with measurement techniques for their parameters it also develops the design of fully differential operational amplifiers and operational floating amplifiers. Operational Amplifiers – Theory and Design, Second Edition is carefully structured and enriched by numerous figures, problems and simulation exercises and is ideal for the purpose of self-study and self-evaluation.

The operational amplifier ("op amp") is the most versatile and widely used type of analog IC, used in audio and voltage amplifiers, signal conditioners, signal converters, oscillators, and analog computing systems. Almost every electronic device uses at least one op amp. This book is Texas Instruments' complete professional-level tutorial and reference to operational amplifier theory and applications. Among the topics covered are basic op amp physics (including reviews of current and voltage division, Thevenin's theorem, and transistor models), idealized op amp operation and configuration, feedback theory and methods, single and dual supply operation, understanding op amp parameters, minimizing noise in op amp circuits, and practical applications such as instrumentation amplifiers, signal conditioning, oscillators, active filters, load and level conversions, and analog computing. There is also extensive coverage of circuit construction techniques, including circuit board design, grounding, input and output isolation, using decoupling capacitors, and frequency characteristics of passive components. The material in this book is applicable to all op amp ICs from all manufacturers, not just TI. Unlike textbook treatments of op amp theory that tend to focus on idealized op amp models and configuration, this title uses idealized models only when necessary to explain op amp theory. The bulk of this book is on real-world op amps and their applications; considerations such as thermal effects, circuit noise, circuit buffering, selection of appropriate op amps for a given application, and unexpected effects in passive components are all discussed in detail. *Published in conjunction with Texas Instruments *A single volume, professional-level guide to op amp theory and applications *Covers circuit board layout techniques for manufacturing op amp circuits.

Compact Low-Voltage and High-Speed CMOS, BiCMOS and Bipolar Operational Amplifiers discusses the design of integrated operational amplifiers that approach the limits of low supply voltage or very high bandwidth. The resulting realizations span the whole field of applications from micro-power CMOS VLSI amplifiers to 1-GHz bipolar amplifiers. The book presents efficient circuit topologies in order to combine high performance with simple solutions. In total twelve amplifier realizations are discussed. Two bipolar amplifiers are discussed, a 1-GHz operational amplifier and an amplifier with a high ratio between the maximum output current and the quiescent current. Five amplifiers have been designed in CMOS technology, extremely compact circuits that can operate on supply voltages down to one gate-source voltage and two saturation voltages which equals about 1.4 V and, ultimate-low-voltage amplifiers that can operate on supply voltages down to one gate-source voltage and one saturation voltage which amounts to about 1.2 V. In BiCMOS technology five amplifiers have been designed. The first two amplifiers are based on a compact topology. Two other amplifiers are designed to operate on low supply voltages down to 1.3 V. The final amplifier has a unity-gain frequency of 200 MHz and can operate down to 2.5 V. Compact Low-Voltage and High-Speed CMOS, BiCMOS and Bipolar Operational Amplifiers is intended for the professional analog designer. Also, it is suitable as a text book for advanced courses in amplifier design.