A SiGe switched LNA for X-band phased-arrays

This paper presents a switched low-noise amplifier (LNA), for the first time at X-band (8-12 GHz) frequencies, fabricated in 0.25-μm SiGe BiCMOS process. The switched LNA is based on single stage bipolar cascode topology to achieve lower noise figure and higher gain, simultaneously. The switching circuitry is designed by a series isolated NMOS switch. We also present, for the first time in switched LNAs, the utilization of resistive body floating technique to increase power handling (IP_1dB) in bypass mode. Measurement results show that, in gain mode, LNA achieves a noise figure of 1.6-1.9 dB and a gain of 9.5-11.5 dB in 8-12 GHz band. The input-referred P_1dB is -6 dBm at 10 GHz and the power consumption is 18.6 mW. In bypass mode, the switched LNA achieves a measured insertion loss of 6 dB and an input-referred P_1dB of 17.4 dBm at 10 Ghz, with 1 μW power consumption. The chip area is 0.52×0.58 mm².