An eighth-order CMOS lowpass filter with 30-120 Mhz tuning range and programmable boost

A CMOS lowpass filter with programmable cutoff frequency is presented. The architecture is gm/C type with the gm controlled through a resistor servo approach. The wide tuning range is achieved by exploiting a dual loop control over a degenerated differential pair. This filter, implemented in a 0.25 µm 2.5V CMOS technology, dissipates 120mW with fc=120MHz and has a die area of 0.23mm².