Design of Low-loss and Highly-selective Cmos Active Bandpass Filter at K-band

In this paper, a second-order Chebyshev active bandpass filter (BPF) with three finite transmission zeros is presented. The filter utilizes a tapped-inductor feedback technique to compensate resistive losses of on-chip inductors, and a shunt-feedback inductor between input and output ports to achieve the transmission zeros. Moreover, one transmission zero is in the lower stopband, and two transmission zeros are in the upper stopband, thus improving the selectivity of the filter significantly. The filter is designed and fabricated in a standard 0.18-μm CMOS technology with a chip area of 0.57mm × 0.65mm including all testing pads. The circuit draws 6 mA from a 0.7-V supply voltage. Additionally, the filter achieves a 1.65-dB insertion loss and 13.2-dB return loss with a 17% 3-dB bandwidth at 23.5 GHz. The measured NF and input P1 dB is 6.7 dB and −3.5 dBm. The rejection levels at the transmission zeros are greater than 15.2 dB. Finally, the large-signal characterizations are also investigated by the 1-dB compression point (P1 dB) of the filter.