An improved frequency compensation technique for CMOS operational amplifiers
TL;DR: In this paper, a two-stage CMOS operational amplifier is proposed to provide stable operation for a much larger range of capacitive loads, as well as much improved V/SUB BB/ power supply rejection over very wide bandwidths for the same basic operational amplifier circuit.
Abstract: The commonly used two-stage CMOS operational amplifier suffers from two basic performance limitations due to the RC compensation network around the second gain stage. First, it provides stable operation for only a limited range of capacitive loads, and second, the power supply rejection shows severe degradation above the open-loop pole frequency. The technique described provides stable operation for a much larger range of capacitive loads, as well as much improved V/SUB BB/ power supply rejection over very wide bandwidths for the same basic operational amplifier circuit. The author presents a mathematical analysis of this new technique in terms of its frequency and noise characteristics followed by its implementation in all n-well CMOS process. Experimental results show 70-dB negative power supply rejection at 100 kHz and an input noise density of 58 nV/(Hz)/SUP 1/2/ at 1 kHz.
Citations
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Book•
01 Jan 1999
TL;DR: The analysis and design techniques of CMOS integrated circuits that practicing engineers need to master to succeed can be found in this article, where the authors describe the thought process behind each circuit topology, but also consider the rationale behind each modification.
Abstract: The CMOS technology area has quickly grown, calling for a new text--and here it is, covering the analysis and design of CMOS integrated circuits that practicing engineers need to master to succeed. Filled with many examples and chapter-ending problems, the book not only describes the thought process behind each circuit topology, but also considers the rationale behind each modification. The analysis and design techniques focus on CMOS circuits but also apply to other IC technologies.
Table of contents
1 Introduction to Analog Design
2 Basic MOS Device Physics
3 Single-Stage Amplifiers
4 Differential Amplifiers
5 Passive and Active Current Mirrors
6 Frequency Response of Amplifiers
7 Noise
8 Feedback
9 Operational Amplifiers
10 Stability and Frequency Compensation
11 Bandgap References
12 Introduction to Switched-Capacitor Circuits
13 Nonlinearity and Mismatch
14 Oscillators
15 Phase-Locked Loops
16 Short-Channel Effects and Device Models
17 CMOS Processing Technology
18 Layout and Packaging
4,826 citations
TL;DR: In this paper, a 1.5-V, 10-bit, 14.3-MS/s pipeline analog-to-digital converter was implemented in a 0.6/spl mu/m CMOS technology.
Abstract: A 1.5-V, 10-bit, 14.3-MS/s pipeline analog-to-digital converter was implemented in a 0.6 /spl mu/m CMOS technology. Emphasis was placed on observing device reliability constraints at low voltage. MOS switches were implemented without low-threshold devices by using a bootstrapping technique that does not subject the devices to large terminal voltages. The converter achieved a peak signal-to-noise-and-distortion ratio of 58.5 dB, maximum differential nonlinearity of 11.5 least significant bit (LSB), maximum integral nonlinearity of 0.7 LSB, and a power consumption of 36 mW.
966 citations
Cites methods from "An improved frequency compensation ..."
...Cascode compensation [ 10 ], [11] was used to improve the bandwidth over conventional Miller compensation....
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TL;DR: A new method for determining component values and transistor dimensions for CMOS operational amplifiers (op-amps) is described, showing in detail how the method can be used to size robust designs, i.e., designs guaranteed to meet the specifications for a variety of process conditions and parameters.
Abstract: We describe a new method for determining component values and transistor dimensions for CMOS operational amplifiers (op-amps). We observe that a wide variety of design objectives and constraints have a special form, i.e., they are posynomial functions of the design variables. As a result, the amplifier design problem can be expressed as a special form of optimization problem called geometric programming, for which very efficient global optimization methods have been developed. As a consequence we can efficiently determine globally optimal amplifier designs or globally optimal tradeoffs among competing performance measures such as power, open-loop gain, and bandwidth. Our method, therefore, yields completely automated sizing of (globally) optimal CMOS amplifiers, directly from specifications. In this paper, we apply this method to a specific widely used operational amplifier architecture, showing in detail how to formulate the design problem as a geometric program. We compute globally optimal tradeoff curves relating performance measures such as power dissipation, unity-gain bandwidth, and open-loop gain. We show how the method can he used to size robust designs, i.e., designs guaranteed to meet the specifications for a variety of process conditions and parameters.
540 citations
TL;DR: In this article, the authors proposed a solution to the present bulky external capacitor low-dropout (LDO) voltage regulators with an external capacitorless LDO architecture, where the large external capacitor used in typical LDOs is removed allowing for greater power system integration for system-on-chip (SoC) applications.
Abstract: This paper proposes a solution to the present bulky external capacitor low-dropout (LDO) voltage regulators with an external capacitorless LDO architecture. The large external capacitor used in typical LDOs is removed allowing for greater power system integration for system-on-chip (SoC) applications. A compensation scheme is presented that provides both a fast transient response and full range alternating current (AC) stability from 0- to 50-mA load current even if the output load is as high as 100 pF. The 2.8-V capacitorless LDO voltage regulator with a power supply of 3 V was fabricated in a commercial 0.35-mum CMOS technology, consuming only 65 muA of ground current with a dropout voltage of 200 mV. Experimental results demonstrate that the proposed capacitorless LDO architecture overcomes the typical load transient and ac stability issues encountered in previous architectures.
484 citations
TL;DR: A silicon compilation system for CMOS operational amplifiers (OPASYN) is discussed, which produces a design-rule-correct compact layout of an optimized operational amplifier.
Abstract: A silicon compilation system for CMOS operational amplifiers (OPASYN) is discussed. The synthesis system takes as inputs system-level specifications, fabrication-dependent technology parameters, and geometric layout rules. It produces a design-rule-correct compact layout of an optimized operational amplifier. The synthesis proceeds in three stages: (1) heuristic selection of a suitable circuit topology; (2) parametric circuit optimization based on analytic models; and (3) mask geometry construction using a macro cell layout style. The synthesis process is fast enough for the program to be used interactively at the system design level by system designers who are inexperienced in operational amplifier design. >
374 citations
References
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TL;DR: In this paper, an overview of current design techniques for operational amplifiers implemented in CMOS and NMOS technology at a tutorial level is presented, focusing on CMOS amplifiers because of their more widespread use.
Abstract: Presents an overview of current design techniques for operational amplifiers implemented in CMOS and NMOS technology at a tutorial level. Primary emphasis is placed on CMOS amplifiers because of their more widespread use. Factors affecting voltage gain, input noise, offsets, common mode and power supply rejection, power dissipation, and transient response are considered for the traditional bipolar-derived two-stage architecture. Alternative circuit approaches for optimization of particular performance aspects are summarized, and examples are given.
493 citations
TL;DR: In this article, a new CMOS PCM channel filter is described, which includes transmit and receive filters on a single die, and the chip displays an idle-channel noise of typically 0 dBrnC0, a power supply rejection ratio of 40-50 dB at 1 kHz, and a fully operational power dissipation of only 35 mW.
Abstract: A new CMOS PCM channel filter is described, which includes transmit and receive filters on a single die. This chip displays an idle-channel noise of typically 0 dBrnC0, a power supply rejection ratio of 40-50 dB at 1 kHz, and a fully operational power dissipation of only 35 mW, making it very cost effective in telecommunication switching systems. The design of this chip, including architectural, switched capacitor filter, and amplifier considerations is described, and typical experimental results are presented.
130 citations
TL;DR: A high performance operational amplifier 300 mil/SUP 2/ in area has been designed and fabricated in a standard n-channel silicon-gate enhancement/depletion MOS process.
Abstract: A high performance operational amplifier 300 mil/SUP 2/ in area has been designed and fabricated in a standard n-channel silicon-gate enhancement/depletion MOS process. Specifications achieved include open-loop gain, 1000; power consumption, 10 mW; common-mode range within 1.5 V of either supply rail; unity-gain bandwidth, 3.0 MHz with 80/spl deg/ phase margin; RMS input noise (2.5 Hz-46 kHz), 25 /spl mu/V; C-message weighted noise -5 dBrnC; and 0.1-percent settling time, 2.5 /spl mu/s.
106 citations
01 Aug 1981
TL;DR: In this paper, a complete PCM codec using charge redistribution and switched-capacitor techniques is described, implemented in a two-level polysilicon CMOS technology using 23.4 mm/SUP 2/ of active area.
Abstract: A complete PCM codec using charge redistribution and switched-capacitor techniques will be described. The device is implemented in a two-level polysilicon CMOS technology using 23.4 mm/SUP 2/ of active area. It features all the required transmission filters needed for telephony, two on-chip voltage references, TTL compatible digital interfaces, and low-power dissipation. The architecture of the chip allows asynchronous operation, a variable PCM data rate from 100 kbit/s to 4.096 Mbit/s, /spl mu//A law operation via pin selection, and gain selection at either of two levels in each direction.
27 citations
TL;DR: Low-power CMOS op amps with high-drive capability and good settling characteristics are described, suitable for applications in such systems as charge-redistribution codecs and switched-capacitor filters.
Abstract: Low-power CMOS op amps with high-drive capability and good settling characteristics are described. One circuit, occupying 150 mils/sup 2/ of active area and consuming 1 mW of power drives a capacitive load of up to 150 pF with greater than +-2.5 V/µs slew rates and less than 3.5 µs settling time to 0.1 percent. A somewhat larger circuit drives low-resistance (e.g., 600 Omega) and high-capacitance (1000 pF) loads with better slew rates and settling time. These circuits are suitable for applications in such systems as charge-redistribution codecs and switched-capacitor filters.
23 citations