Design of a Wide-band Low-voltage CMOS Filter for Wireless Transceiver Systems

This paper presents a wideband low voltage tunable CMOS filter for wireless transceivers systems. The proposed filter attempts to optimize the performance of the circuit as it operates at relatively low voltage providing wide tunable range at the same time. It is constructed using Gm-C technique employing three Operational Transconductance Amplifiers (OTA) and two grounding capacitors. The filter is of second order with cutoff frequency (fc) at 5 MHz and Quality factor of 1. The filter also exhibits independent electronic tuning of (fc) and quality factor (Q) providing more accuracy in its frequency response. Also, its circuit can also be synthesized to produce multiple other filter frequency responses by varying inputs which can be beneficial in other applications. The OTA is the main active element in the filter operating at input supply voltage of 1 V and having open loop dc gain of 38 dB with power dissipation of 270 uW. The unit gain frequency is at 36 MHz and the phase margin angle is at 65 degrees. Simulations are done in HSPICE using CMOS 0.18μm process parameters as functional verification of the presented theory.