A CMOS 4.35-mW +22-dBm IIP3 Continuously Tunable Channel Select Filter for WLAN/WiMAX Receivers

A low-power high linearity CMOS G_m-C channel select filter for WLAN/WiMAX receivers in 90-nm CMOS technology is presented. To reduce power consumption a biquad cell with simple architecture is used. A simple but efficient technique is also proposed to improve the linearity of the filter without increasing its power consumption. Coarse and fine tuning techniques are used to tune the cutoff frequency of the sixth-order Butterworth low-pass filter from 8.1 MHz to 13.5 MHz suitable for WLAN and WiMAX applications. The measurement results show an in-band IIP3 of + 22 dBm, an HD3 better than - 40 dB at 470 mV_P input signal amplitude, and an input referred noise of 75 nV/√Hz at a power consumption of 4.35 mW from a 1-V supply. The differential filter occupies a chip area of 0.239 mm² excluding pads.