A compact band selection filter in 0.18-μm CMOS technology

A compact band selection filter (BSF) is implemented in a 0.18-μm CMOS technology. The structure consists of a pair of symmetric slow wave anti-coupled line and a shunted transistor. When the transistor is in the off-state, the BSF can work as a low-pass filter. The measured insertion loss is 3 dB, and the return loss is better than 9 dB from DC to 10GHz. When the transistor is in the on-state, the BSF can work as a bandpass filter. The measured insertion loss is 3 dB, and the return loss is better than 10 dB from 14 to 27 GHz.