A Wide Tuning Range G/109–C Filter for Multi-Mode CMOS Direct-Conversion

Abstract

A third-order channel selection filter for multi-mode direct-conversion receivers is presented. The filter is designed with a Butterworth prototype and with the target wireless appli- cations of Bluetooth, cdma2000, Wideband CDMA, and IEEE 802.11a/b/g/n wireless LANs. Linear-region MOS transistors are used to perform voltage-to-current conversion. The wide tuning range is achieved by the current multipliers and linear voltage-to-current converters. Implemented in the TSMC 0.18 m CMOS process, the measurement results show that the filter can operate successfully over a cutoff frequency range of 500 kHz to 20 MHz, and is compliant with the requirements of different wire- less applications. The power consumption is 4.1 mW to 11.1 mW for minimum and maximum cutoff frequencies respectively from a 1.2 V supply voltage. The circuit performance compares favorably with previously reported works.