A low-noise low-IF 0.18μm CMOS receiver IC with an active on-chip channel-selection filter for 5GHz wireless applications

We have developed a low-noise one-chip receiver IC using a low-IF architecture. The IC includes an active channel-selection band pass filter (BPF) for the IEEE802.11a standard. To improve both its total noise figure (NF) and image-rejection ratio, we employ an RC-bridge-type phase shifter which provides a ±45° phase difference. An overall NF as low as 11dB and a 32dB image-rejection ratio was achieved with the 0.18μm CMOS IC, which comprises low-noise amplifiers (LNAs), image-rejection mixers, a quadrature voltage-controlled oscillator (VCO), a phase-locked loop (PLL), the BPF, and IF amplifiers.