Sub-μW switched-capacitor circuits using a class-C inverter

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Abstract

In a switched-capacitor (SC) circuit, the major block is an operational transconductance amplifier (OTA) designed in order to form a feedback loop. However, the OTA is the block that consumes most of the power in SC circuits. This paper proposes the use of a class-C inverter instead of the OTA in SC circuits and a corresponding switches configuration for extremely low power applications. A detailed analysis and design trade-offs are also provided. Simulation and experimental results show that sufficient performance can be obtained even though a class-C inverter is used. The second-order biquad filter and the second-order SC sigma-delta (∑Δ) modulator based on a class-C inverter are designed. These circuits have been fabricated with a 0.35-μm CMOS process. The measurement results of the fabricated SC biquad filter show a 59-dB signal-to-noise-plus-distortion ratio (SNDR) for a 0.2-Vp-p input signal and 0.9-V dynamic ranges. The power consumption of the biquad filter is only 0.4μW with a 1-V power supply. The measurement results of the fabricated ∑Δ modulator show a 61-dB peak SNR for a 1.6-kHz bandwidth with a sample rate of 200kHz. The modulator consumes 0.8μW with a 1-V power supply.

Original languageEnglish
Pages (from-to)1313-1318
Number of pages6
JournalIEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
VolumeE88-A
Issue number5
DOIs
Publication statusPublished - 2005 Jan 1

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All Science Journal Classification (ASJC) codes

  • Signal Processing
  • Computer Graphics and Computer-Aided Design
  • Applied Mathematics
  • Electrical and Electronic Engineering

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