Switched-Opamp Circuits

This paper proposes a novel finite-gain nonlinearity in MDACs of pipelined ADCs or poles and zeros compensation technique that can be applied to low-voltage deviations in SC filters or sigma-delta modulators, unless the high-speed resetand switched-opamp circuits. The proposed produced finite-gain error can be compensated, with, for example, technique utilizes an Auxiliary Differential-Difference traditional Correlated Double Sampling (CDS) techniques [8,9]. Amplifier (A-DDA) that senses and corrects the finite-gain However this cannot be applied in a low-voltage environment due error from the virtual ground of the main opamp (with the to (a) limitations caused by the floating switch problems and (b) the effective gain in the order of jA2), thus allowing the use of fact that the opamp is switched off or reset in one clock phase, high-speed single-stage low-gain opamps (instead of usual lowwhich implies that it would not be idle and cannot be used to speed two-stage amplifier with large power consumption) to compensate the gain error. To overcome these drawbacks a lowachieve high-speed operation. Simulations of a reset-opamp 10voltage finite-gain compensation technique can be used [4], but it bit 100 MHz pipelined ADC in 1.2-V supply voltage are has also a restriction of narrow-band operation (typically a bandpass presented using 0.18pm CMOS, with the Signal-to-Noise-andsigma-delta modulator) that limits the signal band to be located only Distortion Ratio (SNDR) improved from 46.77 dB to 58.51 dB narrowly atf/4. and thus verifying the effectiveness of the proposed circuit. In this paper a novel low-voltage finite-gain-compensation technique is proposed. It utilizes an Auxiliary Differential