A wideband CMOS LNA with varactor tuned input matching for WLAN/WiMAX applications

A wideband CMOS low noise amplifier covering 2.3-2.7 GHz is designed for WLAN/WiMAX applications. Continuously tuned wideband characteristics are obtained by employing a novel tunable input matching circuit that is configured as back-to-back connected MOS varactors. The back-to-back structure significantly increases the capacitance variation ratio compared to the conventional single varactor structure. The LNA with the varactor tuned input capacitance is designed as a fully differential cascode type in a 0.13 ¿m CMOS process. It covers the frequency band between 2.3 and 2.7 GHz, and obtains a gain of 26.2 dB, a noise figure of 0.98 dB, IIP3 of -14.6 dBm across the total band. It draws 14.8 mA from a 1.2 V supply voltage.