Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1122 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. SC-20, NO. 6, DECEMBER 1985 A High-Performance Micropower Switched-Capacitor Filter RINALDO CASTELLO AND PAUL R. GRAY, FELLOW, IEEE ,4mtract MOS technology scaling requires the use of lower supply voltages. Analog circuits operating from a low supply and achieving a sufficiently farge dynamic range must be designed if analogidigital inter- faces are to be implemented in scaled technologies. This paper describes a high-performance fifth-order low-pass switched-capacitor filter operating from a single 5-V supply. The filter uses a fully differential topology combined with input-to-output class A B amplifier design, dynamic biasing, and switched-capacitor common-mode feedback (CMFB). An experimental prototype fabricated in a 5- p m CMOS technology requires orlly 350 pW of power to meet the PCM channel filter requirements. Typical measured results are a dynamic range of 92 dB, a supply rejection (PSRR) of 40 dB over the entire Nyquist range, and a total harmonic distortion (THD) of 73 dB for a 2-V rms dlfferentiaf output signal. The chip active area is about 3900 milz. I. INTRODUCTION T HE PERFORMANCE of switched-capacitor filters has steadily improved during the last several years, primarily as a result of improvements in the performance of CMOS operational amplifiers. This improvement has been particularly evident in the PCM channel filter appli- cation [1][6]. However, the most recent commercial PCM filter implementations still require a power-per-pole of about 1 mW and operate from a ~ 5 V supply. It has recently been shown [20], [21] that, from a fundamental standpoint, the absolute minimum achievable power dis- sipation in a voice-band filter with a dynamic range of 90 dB in a 3-pm technology operated from a +-5 V supply is less than 1 pW per pole. A large margin for improvement in power consumption over existing filter designs is there- fore possible in principle. The realization of such a reduc- tion, while maintaining high-performance levels, would have important implications in the realization of battery- operated analog/digital interfaces. A second important consideration in the realization of switched-capacitor filters is the fact that the technological scaling of the mainstream MOS technologies dictates the use of lower power-supply voltages [7]. This fact, and the need for an analog/digital compatible technology, create a strong motivation for developing new analog circuit tech- niques suitable for low-voltage operation. Recently several circuit approaches to the implementa- tion of low-power MOS switched-capacitor filters have Manuscript received October 25, 1985; revised August 1, 1985. This work was supported by NSG Grants ECS-8023872 and ECS-81OOO12, The authors are with the Department of Electrical Engineering and Computer Science, University of California, Berkeley, Berkeley, CA 94720....
View Full Document

Page1 / 11


This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online