A high-selectivity active bandpass filter using gyrator based resonators in 0.13-μm CMOS

An active bandpass filter with high selectivity is presented. The design employs proposed active resonators. By properly cascading multiple resonators, a bandpass response is achieved with good selectivity and passband flatness. To prove the concept, a 7-stage bandpass filter in standard 0.13 μm CMOS is realized. The measured 1 dB bandwidth is 1.35-2.53 GHz. The out-of-band rejection is better than 40 dB below 1.06 GHz and above 2.89 GHz. The input referred 1 dB compression point is -16 dBm. With proper sizing of the tail transistor in the transconductor, the measured common mode suppression is better than 45 dB. The core part of the filter occupies 1.4×0.12 mm² and consumes 24 mA at a 1.2 V supply voltage.