High-frequency high-Q BiCMOS current-mode bandpass filter and mobile communication application

The design of a tunable high-frequency fully integrable current-mode bandpass filter is presented using a complementary high-performance BiCMOS process. The new architecture of this filter is based on impedance simulation and employs current controlled conveyors. The Q-factor and the center frequency can be electronically controlled with dc bias currents over a broad range of values, thus allowing easy tuning of this filter. An application to a mobile communication IF receiver channel centered at 85 MHz and with 1-MHz bandwidth based on the cascade of two identical second-order bandpass cells has been designed. Measurements show very interesting frequency performance (f ₀ tunable in the range 30-120 MHz and Q from 1-140) in conjunction with low power consumption (25 mW for the fourth-order filter with ±2.5 V supplies)