A 2nd Order Current Mode Filter with 14dB Variable Gain and 650MHz to 1GHz Tuning Range in 28nm CMOS
An open loop baseband filter with bandwidth of 1GHz suitable for a receiver operated in the 5G high frequency band (above 24GHz) is presented. The filter is based on a gain boosted Common Gate topology that implements a 2nd order low pass filter in the current domain. A frequency dependent active negative capacitance circuit is used to boost the quality factor of the filter. This not only improves in band flatness but also increases out of band selectivity. A test chip has been realized in 28nm CMOS technology. The filter bandwidth can be programmed from 650 MHz to 1 GHz and the current gain changed by 14 dB, with the power dissipation scaling from 11 mW to 5 mW. In band IIP3 is +2 dBm and the input noise integrated from 10 MHz to 1 GHz is lower than 170 mVrms.
2021 IEEE International Symposium on Circuits and Systems (ISCAS)