A Very Wideband Active RC Polyphase Filter with Minimum Element Value Spread Using Fully Balanced OTA Based on CMOS Inverters

Special Section on Analog Circuits and Related SoC Integration Technologies

The Institute of Electronics, Information and Communication Engineers">Keishi KOMORIYAMA, Presently, FUJITSU VLSI LIMITED">Makoto YASHIKI, Presently, Panasonic Semiconductor Systems and Technology Co.">Eiichi YOSHIDA, The Institute of Electronics, Information and Communication Engineers">Hiroshi TANIMOTO

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Keywords: active RC polyphase filter, fully differential OTA, CMOS inverter, wideband, element value spread

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2008 Volume E91.C Issue 6 Pages 879-886

DOI https://doi.org/10.1093/ietele/e91-c.6.879

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Abstract

This paper presents a very wideband active RC polyphase filter (ARCPF). We propose a unit section of the ARCPF, which is an ordinary RCPF followed by opamps with parallel RC feedback. In the proposed unit section, pole and zero can be assigned independently. By using the unit ARCPFs, a very wideband image rejection filter can be realized by cascading the sections, which can greatly reduce the element value spread. To realize this, CMOS inverter based fully differential OTA which can operate under low supply voltage is also presented. This paper describes a six-stage active RC polyphase filter with 1-100MHz passband in 0.18μm CMOS technology.

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