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 (IP1dB) 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 P1dB 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 P1dB of 17.4 dBm at 10 Ghz, with 1 µW power consumption. The chip area is 0.52×0.58 mm².