A low-power switched-capacitor variable gain amplifier

Fujimoto, Yoshihisa; Tani, H.; Maruyama, Masahiko; Akada, H.; Ogawa, H.; Miyamoto, Masayuki

doi:10.1109/jssc.2004.829919

Cited by 31 publications

(20 citation statements)

References 4 publications

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“…The gain selection in VGA1∼2 is controlled by the gain control signals (MSB, D T 1 , D T 2 ). On the other hand, VGA3 has an exponential (linear-in-dB) gain control by a fine step utilizing a local positive feedback [2], which realizes the first-order approximation of the exponential function efficiently. The capacitors are C s = C sP = 4 pF, C f 1 = C fP 1 = 0.5 pF, C f 2 = C fP 2 = 3.5 pF, C I = 1 pF in VGA1, C s = C sP = 2 pF, C f 1 = C fP 1 = 0.5 pF, C f 2 = C fP 2 = 0.5 pF, C f 3 = C fP 3 = 1 pF, C I = 1 pF in VGA2, and C f = C fP = 1.2 pF, C I = 1 pF in VGA3.…”

Section: Circuit Design and Simulation Resultsmentioning

confidence: 99%

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Multi-stage variable gain amplifier for low-voltage CCD analog-front end using CDA technique

Park

Lee

et al. 2010

IEICE Electron. Express

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Abstract:A new technique adopting the correlated-double amplification (CDA) to improve the signal swing of the "linear-in-dB" variable gain amplifier (VGA) under a low-voltage supply is presented. This technique significantly reduces the finite op-amp gain requirement without compromising the speed. An efficient 3-stage VGA is introduced for the signal to swing up to 2/3 of the supply voltage by incorporating 2-stage push-pull op-amps. A design in a 0.13 μm CMOS process under 1.2 V supply is proposed and verified.

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Section: Circuit Design and Simulation Resultsmentioning

confidence: 99%

“…efficient topology for the switched-capacitor (SC) VGA utilizing a local positive feedback was published [2]. Besides, a piecewise linear technique was also adopted to improve the integral nonlinearity of the VGA [3].…”

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confidence: 99%

Multi-stage variable gain amplifier for low-voltage CCD analog-front end using CDA technique

Park

Lee

et al. 2010

IEICE Electron. Express

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“…A CMOS linear-in-dB VGA of the current divider type for CDMA systems [1], and an accurate switched-capacitor (SC) type linear-in-dB VGA for image sense systems were reported [2]. A possible implementation in the SC type VGA utilizes the 1st-order approximation of the exponential function [3].…”

Section: Introductionmentioning

confidence: 99%

“…A possible implementation in the SC type VGA utilizes the 1st-order approximation of the exponential function [3]. The conventional CMOS linear-in-dB VGA uses a single curve for the implementation, which can achieve a gain from 0 to 6 dB by 0.094 dB step (8 bit resolution from 0 to 24 dB) [2]. By the way, the recent CCD systems tend to require a more sophisticated gain control [4], looking for a new topology.…”

Section: Introductionmentioning

confidence: 99%

“…1 (a) depicts the circuit diagram of the proposed piecewise-linear-in-dB VGA (P-VGA). It basically adopts the conventional single-curve architecture [2], except that the reference capacitor (C a ) which is supposed to be fixed is varied in the sectionalized code ranges. During the sampling phase (ϕ 1 ), the reference capacitor C a and the variable capacitor C x sample the differential input signal, V + in and V − in , and C i samples the offset voltage of the op-amp.…”

Section: Introductionmentioning

confidence: 99%

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Piecewise linear-in-dB variable gain amplifier to enhance integral nonlinearity

Kim

Nam

Kim

2009

IEICE Electron. Express

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Abstract:A new technique to improve the integral nonlinearity of the "linear-in-dB" variable gain amplifier (VGA) by adopting a piecewise linear transfer curve rather than a single curve is presented. The conventional single curve which is the first-order approximation of the exponential function yields bigger deviation errors as the gain control code advances. The integral nonlinearity (INL) of the proposed piecewise linear curve can be managed to be smaller because one of divisional curves moves to another before the deviation becomes prominent. A generic circuit schematic without chip size overhead is suggested with its future expansion in mind, and a design in a 0.35 μm CMOS process under 3.3 V supply is proposed and verified.

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A switched‐capacitor programmable gain amplifier using dynamic element matching

Wang

Matsuoka

Taniguchi

2007

IEEJ Transactions Elec Engng

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This paper discusses the effect of capacitor mismatch errors on gain accuracy of switched‐capacitor programmable gain amplifier (SC PGA). To improve gain deviations caused by mismatch errors, the dynamic element matching (DEM) algorithm is applied to the SC PGA circuits. It uses digital gain‐control signal to dynamically vary the matched capacitor combinations so that the effective capacitances of the sampling and feedback capacitor arrays are averaged, and thus the gain deviations due to capacitor mismatch errors are eliminated to a significant extent. The distortion caused by mismatch errors shift to certain frequency bands, and could be reduced or removed by subsequent processing such as lowpass filtering. A 4‐bit SC PGA using DEM was designed in 0.25 µm CMOS process with 2.5 V voltage supply, including offset cancellation and clock bootstrapped circuits operating at a sampling frequency of 10 MHz. Test results have indicated that gain deviations due to mismatch errors are substantially reduced. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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A low-power switched-capacitor variable gain amplifier

Cited by 31 publications

References 4 publications

Multi-stage variable gain amplifier for low-voltage CCD analog-front end using CDA technique

Multi-stage variable gain amplifier for low-voltage CCD analog-front end using CDA technique

Piecewise linear-in-dB variable gain amplifier to enhance integral nonlinearity

A switched‐capacitor programmable gain amplifier using dynamic element matching

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