A 5-GHz BiCMOS variable-gain low noise amplifier with inductorless low-gain branch

A 5-GHz variable-gain low noise amplifier without using an excess inductor in its low-gain mode has been demonstrated. When the LNA's gain is reduced from 16.3 dB to 5.8 dB, its IIP3 is improved from -7.8 dBm to +1.1 dBm and current consumption is reduced from 3 mA to 2 mA. The noise figures in the high- and low-gain modes are 3.5 dB and 8.3 dB, respectively. Input and output impedance matching are well maintained in both modes. The amplifier is also unconditionally stable from 100 MHz to 10 GHz.