A front-end filter with automatic center frequency tuning circuitry

A new automatic tuning circuit based on synchronous rectification scheme is proposed. The direct tuning circuit functions in the idle periods between the burst-mode transmissions. The proposed CMOS tuning circuit can be fully integrated with the front-end filter. Simulation results employing 0.5 /spl mu/m CMOS technology have verified that the center frequency is automatically tuned to 1.25 GHz with 10% process variation presence. The deviation is 15 MHz, representing to only 1.2% error. The tuning circuit dissipates 34 mW power.