A tunable active filter in CMOS for RF applications

An active radio frequency (RF) filter based on floating active inductor circuits is presented in this work. For demonstration purposes, a third-order Chebyshev lowpass filter with an LC ladder structure has been designed for GSM applications. The filter has a cutoff frequency of 900 MHz and 0.4 dB ripple, and is tunable between 890 MHz and 960 MHz, consumes 10.5 mW power, and occupies an area of 96 mumtimes135 mum when laid out using the UMC 0.13 mum CMOS process which provides an area reduction of 80% compared to its passive filter counterpart.