Journal ArticleDOI
An improved frequency compensation technique for CMOS operational amplifiers
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TLDR
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.read more
Citations
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Journal ArticleDOI
A two-stage CMOS OTA with enhanced transconductance and DC-gain
TL;DR: In this paper, an ultra-low power process-insensitive two-stage OTA working in weak inversion region with enhanced transconductance and DC gain is presented, where a pseudo-cascode frequency compensation technique is applied in this design to improve the phase margin and accordingly robust the stability of the proposed OTA.
Book ChapterDOI
Sigma–Delta Modulation
TL;DR: The sigma-delta modulator is a specific algorithm to convert low-bandwidth signals into a digital data stream and the effects of oversampling are described.
Proceedings ArticleDOI
Effects of resistive loading on unity gain frequency of two-stage CMOS operational amplifiers
U. Dasgupta,Yong Ping Xu +1 more
TL;DR: The final outcome of this effort is the introduction of two resistive load dependent correction factors, which when applied to the traditional formulae predicts, reasonably accurately, the shifting of the open-loop poles and the unity gain frequency with any amount of resistive loading.
Patent
Feedforward cancellation of power supply noise in a voltage regulator
TL;DR: In this paper, a voltage regulator that provides feedforward cancellation of power supply noise is described, which includes a process tracking circuit that receives a supply voltage and generates a proportional voltage.
A High Gain Multi-Stage Operational Amplifier using Compound Transconductance Element
TL;DR: A compound transconductance element based operational amplifier has been developed that achieves an open-loop gain in excess of 100 dB and is applicable to continuous-time and switched-capacitor applications that require high linearity.
References
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Journal ArticleDOI
MOS operational amplifier design-a tutorial overview
Paul R. Gray,Robert G. Meyer +1 more
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.
Journal ArticleDOI
A high performance low power CMOS channel filter
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.
Journal ArticleDOI
High-performance NMOS operational amplifier
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.
Journal ArticleDOI
A single-chip CMOS PCM codec with filters
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.
Journal ArticleDOI
Low-Power High-Drive CMOS Operational Amplifiers
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.