Programmable baseband filter for multistandard mobile phones

  • Authors:
  • Rasmus Glarborg Jensen;Kåre Tais Christensen;Erik Bruun

  • Affiliations:
  • Nokia Denmark A/S;Nokia Denmark A/S;Technical University of Denmark, Ørsted - DTU

  • Venue:
  • Analog Integrated Circuits and Signal Processing - Special issue: Selected papers from the NORCHIP 2001 conference
  • Year:
  • 2003

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Abstract

This paper describes a channel selection filter for mobile communication systems using a direct down conversion architecture. The filter can be programmed to meet the requirements of different communication standards, including GSM (Global System for Mobile communication), WCDMA (Wideband Code Division Multiple Access), and Bluetooth. The filter includes a novel DC offset compensation circuit that combines offset sampling in GSM mode with high pass filtering in WCDMA mode. The filter can be programmed to different noise performance levels by programming the impedance level and power consumption of the input transconductor. The entire filter consumes between 2.5 mW and 7.5 mW, depending on the desired noise performance. It is implemented in a standard 0.25 µm CMOS process. A test circuit has been developed and fabricated and measurements show that both the required programmability and the required transfer functions can be obtained from the designed circuit.