Power Efficient Switched-Capacitor Circuit Techniques

Physical Sciences : Electrical

Available for non-exclusive licensing


  • Shouli Yan, Ph.D. , Electrical and Computer Engineering
  • Zhiheng Cao , Electrical and Computer Engineering

Background/unmet need

Switched-capacitor circuits are widely used in the IC (integrated circuit) industry for analog signal processing, amplifiers, filters, analog-to-digital (A/D) and digital-to-analog (D/A) converters, and oscillators. The need for making these circuits low-power is becoming increasingly important, due to the proliferation of portable electronic devices and the push for reduced power consumption. Low-power circuits are also essential to cut costs in manufacturing and to reduce cooling and maintenance expenses. The reduction in cooling devices required on chips also benefits design by creating more room for additional components integrated on a single chip.

Invention Description

The proposed amplifier in this technology consumes less power, takes smaller silicon area, and has lower input referred noise compared to conventional telescopic and folded-cascode amplifiers. The proposed circuits and principles can be applied to other switched-capacitor circuits, such as switched-capacitor amplifiers, filters, and A/D and D/A converters. To prove the concept of the proposed techniques, a fifth-order single-loop single-bit sigma-delta modulator using CMOS technology was created. The experimental results proved the effectiveness of the proposed techniques for ADCs.


  • Proposed techniques will consume 20% to 50% of the power consumed by conventional switched-capacitor circuits.
  • The proposed amplifier only consumes around 40% to 50% of the current/power compared with telescopic amplifiers and around 20% to 25% compared with folded-cascode amplifiers.


    Current-reuse and the unlimited slew-rate of the proposed amplifier make it possible to achieve complete settling with minimal power consumption.

Market potential/applications

Switched-capacitor circuits are used widely in mixed-signal ICs. Applications include MP3 players, CD/DVD players, cellular phones, high-definition TVs, digital cameras, and personal computers.

IP Status