Tunable capacitors for digital CMOS compatible high frequency analog filters

Abstract

At high frequencies, the tunable range of traditional gm-C filters is severely reduced due to short channel effects. To allow tuning at high frequencies, a tunable capacitor based on the intrinsic capacitances of a MOSFET transistor can be used. A prototype filter, based on this concept, was tunable from 29-36 MHz, with a dynamic range of 23 dB, and a maximum power dissipation of 30 mW.