A programmable active-RC complex filter for wireless communications

A programmable active-RC complex filter synthesized from Tow-Thomas low-pass prototype is proposed in this paper. The filter features tunable intermediate frequency (f
_IF
), and can be programmed by the external. In addition a tunable damping structure allows to guarantee a minimum image rejection for any value of the tunable range. The filter is implemented in a 0.18 ¿m CMOS technology, consumes 0.36 mW and its response ranges from 40 kHz to 100 kHz (5 kHz per step), the minimum image rejection is 62 dB. The maximum in-band integrated output noise is 132 ¿V
_rms
, while an in-band IM3 of 20 dBc is obtained with v
_in
=140 mV
_rms
.