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A polyphase filter based on CMOS inverters

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Author

Summary, in English

A new idea for generation of quadrature signals on chip is presented. The topology is based on a passive RC polyphase filter, where the resistive parts are made active by using inverters. The active filter combines quadrature generation, isolation, and gain without losing quadrature performance compared to a regular RC polyphase filter. The filter technique is demonstrated in a 10 GHz front-end application where a broadband VCO, having a tuning range of 1.44 GHz, drives an active polyphase filter to generate quadrature LO signals. According to simulations the quadrature phase error shows a typical tuned behavior and stays below 0.8 degrees for the complete tuning range. Since the signal amplitude is high throughout the filter the noise is low, below 160 dBc/Hz at 10 MHz offset. The high amplitude also reduces the need for high gain tuned buffers, thereby enabling significant reductions in chip area.

Publishing year

2007

Language

English

Pages

7-12

Publication/Series

Analog Integrated Circuits and Signal Processing

Volume

50

Issue

1

Document type

Journal article

Publisher

Springer

Topic

  • Electrical Engineering, Electronic Engineering, Information Engineering

Keywords

  • quadrature generation
  • CMOS
  • polyphase filter

Status

Published

ISBN/ISSN/Other

  • ISSN: 0925-1030