Low-cost BiCMOS variable gain LNA at Ku-band with ultra-low power consumption

A low-noise amplifier (LNA) at Ku-band with variable gain for adaptive antenna combining is presented. The compact MMIC is optimized for low-power-consuming wireless local area network applications and is fabricated using commercial 0.25-mum bipolar complementary metal-oxide semiconductor technology. At 16 GHz, a supply voltage of 1.5 V and a current consumption of only 1.5 mA, maximum gain of 14.5 dB, noise figure of 3.8 dB, and third-order intercept point at the output of 1 dBm are measured. At a supply voltage of only 1 V and a supply current of 0.9 mA, a gain of 11 dB was achieved, yielding a gain per supply power figure-of-merit of 12.2 dB/mW, which, to the knowledge of the authors, is the highest reported to date for Ku-band LNAs, independent of the technology used. The characteristics of different bias methods for amplitude control the cascode circuit are elaborately discussed. A bias-control method is proposed to significantly decrease the transmission phase variations versus gain.