A 10/20/40/80 MHz 3rd-order Active-RC Butterworth LPF for 802.11ax Receiver

In this paper, a reconfigurable 10/20/40/80 MHz bandwidth Butterworth active-RC low-pass filter (LPF) in 55 nm CMOS for IEEE 802.11ax receiver is presented. This filter has a programmable in-band gain, which can save additional amplifier circuits and reduce analog baseband power consumption. Programmable capacitor array of the filter is used to adjust bandwidth. Adjust the gain ranging from 0 to 24 dB in-band by programmable resistor array. The prototype filter consumes a current 25.1 mA at 1.5 V supply and occupies 0.084 mm$^{2}$. The spurious free dynamic range (SFDR) of the LPF reaches 71 dB, and the NF is less than 35 dB over the filter’s bandwidth.