4-20 GHz low noise amplifier MMIC with on-chip switchable gate biasing circuit

A broadband low-noise amplifier (LNA) MMIC with a novel onchip switchable gate biasing circuit is proposed. The biasing circuit is able to switch on/off the low noise amplifier and compensate the variation of threshold voltage (Vth) and temperature, hence improving the robustness of the amplifier over a wide operating frequency range. The switching frequency is up to 1 MHz, and the fluctuations of on-state quiescent current and power gain of the amplifier are within +/- 7.9% and +/- 0.8% when the threshold voltage varies from -0.15V to 0.15V. The power gain variation is stabilized within +/- 1.25 dB by the biasing network, while the temperature changes from -55 degrees C to 125 degrees C. Realized in 0.15 mu m E-mode pHEMT technology with size of 2.0 mm x 1.3 mm, the LNA provides a typical gain of 24 dB while maintaining input and output return loss better than 10 dB and the noise figure (NF) of the LNA smaller than 1.6 dB from 4 GHz to 20 GHz.