Integration of SPDT Antenna Switch With CMOS Power Amplifier and LNA for FMICW Radar Front End

Abstract

A single-pole double-throw antenna switch integrated with a CMOS power amplifier (PA) and a low-noise amplifier (LNA) by using a three-piece transmission line transformer (TLT) for a frequency-modulated interrupted continuous-wave (FMICW) radar front end is presented. The three-piece TLT consists of a PA output TL, an LNA input TL, and a TL connected to an antenna. Parallel switches and $\lambda$ /4 effective impedance transformers are used to provide high isolation. Due to the effective integration, the chip size and overall insertion loss are reduced significantly. The measured results demonstrate that the proposed switch achieves an insertion loss of 2.2 (2.6) dB with an isolation of 33 (33.4) dB in the antenna-to-LNA input (PA output to antenna) direction. The chip, including the PA, LNA, and switch, for a 79-GHz FMICW radar front end is fabricated in 65-nm CMOS technology, and its size is 0.394 mm2. The PA output power is 10.2 dBm at 79 GHz, and the LNA gain is 15 dB at 79 GHz. FMICW radar waveforms are successfully generated with the switch in this chip. The measured results verify that the proposed device generates an FMICW radar waveform at the switching frequency at 6 kHz.