A Multimode CMOS Low Noise Amplifier Using Wideband Matching

This paper describes a 0.18 um CMOS wideband multimode LNA for wireless applications, such as WAVE (802.11p), WLAN (802.11a/b/g), WCDMA and Wibro. The circuit topology is a cascode structure with selective input path and wideband output matching for high gain with a low noise figure. By reducing the the quality factor (Q factor) of the narrowband LNA, it can get the flat passband gain. This structure is able to keep high gains in desired bands by adding a buffer. Simulation results show gains of 13.5 dB in 2 GHz and 13 ~ 15 dB over a bandwidth range from 3 to 5 GHz. This LNA achieves noise figures of 2.3 dB and 1.92~2.9 dB and power dissipations of 15.5 mW and 12.5 mW at 2 GHz and 3 ~ 5 GHz bands, under a power supply of 1.8V. The input/output return loss is less than -10 dB.