Quasi-circulator based automotive monostatic transceiver with integrated leakage canceler

A novel 77-GHz monostatic FMCW radar structure for automotive application is proposed. The transmit-receive (TX-RX) signal separation is handled by an active quasi-circulator (QC) with integrated leakage canceler. The down conversion of the receive signal is performed by a single-balanced (SB) mixer to avoid single-ended to differential conversion losses and to reduce the chip area consumption. As the leakage canceler is adjusted with the DC-offset of the mixer, also the LO leakage can be compensated with this approach. To facilitate a linear TX path, a transformer is used to couple the transmit signal. A test chip of the transceiver is fabricated in a 200-GHz f
_T
Silicon-Germanium (SiGe) HBT technology. The performance of the overall system is demonstrated by on-wafer measurements. The transmit insertion loss is around 7 dB, whereas the receive gain is around 21.5 dB at 77 GHz. The receiver noise figure (NF) is measured to be below 17.5 dB at 77 GHz.