- 2019 Institution of Engineering and Technology. All Rights Reserved. A new design method for a second-order bandstop filter is presented. The proposed filter is based on the source follower configuration with a partial positive feedback. The positive feedback is used to increase the quality factor of the filter, and the feed-forward paths are used to create complex zeros. The proposed bandstop filter has electronically tunable centre frequency, bandwidth and attenuation with low power consumption. The proposed design has been simulated in TSMC 180 nm CMOS technology. The filter achieves 5.8 nV/ Hz input-referred noise density. For a 2 GHz input signal, the filter achieves a signal-to-noise ratio of 60 dB for 238 mV 0 P, diff input signal amplitude. The simulated results show that the centre frequency tuning range is between 1.6 and 3 GHz and the bandwidth is tunable from 0.6 to 1 GHz. The filter consumes about 2.5 mW for a supply voltage of 1.8 V at a centre frequency of 2.3 GHz.