Monostatic and Bistatic G-Band BiCMOS Radar Transceivers With On-Chip Antennas and Tunable TX-to-RX Leakage Cancellation

Abstract

This article presents $G$ -band monostatic and bistatic radar transceivers (TRX) incorporating on-chip antennas for short-range high-precision applications. The circuits were fabricated using a silicon–germanium (SiGe) BiCMOS technology offering heterojunction bipolar transistors (HBTs) with $\bf {f}_{\mathbf {T}}/\bf {f}_{\mathbf {MAX}}$ of 300/500 GHz. The monostatic TRX implements a tunable leakage canceller (LC) for enhanced transmitter (TX)-to-receiver (RX) leakage compensation and hence improved detectability of weakly reflecting near targets. A standalone monostatic TRX characterized at on-wafer level achieves 4-dBm maximum output power ( $\bf {P}_{\mathbf {TX}}$ ) and 19-dB peak conversion gain ( $\bf {G}_{\mathbf {RX}}$ ) with 3-dB bandwidths of 18 and 17GHz for the TX and the RX, respectively. The bistatic version reaches $\bf {P}_{\mathbf {TX}}$ of 13 dBm and $\bf {G}_{\mathbf {RX}}$ of 24 dB expanding the 3-dB bandwidths to 32 and 34 GHz for the TX and RX, respectively. A double-folded dipole antenna providing 5-dBi gain at 170 GHz was implemented using localized backside etching (LBE) and integrated with the transceivers. A frequency-modulated continuous-wave (FMCW) radar demonstrator incorporating an external phase-locked loop (PLL) was built to evaluate both TRXs and tunable leakage cancellation feature available in the monostatic variant. The maximum equivalent isotropic radiated power ( $\bf {EIRP}$ ), including on-chip antennas, is 8 and 18 dBm for the monostatic and bistatic TRX, respectively. The radars support sweep bandwidth up to 20 GHz reaching 2.1 cm spatial resolution. For a target at 1 m distance the measured ranging precision is $105~\mu \text{m}$ and $13~\mu \text{m}$ for monostatic and bistatic TRX, accordingly. Activation of leakage cancellation effectively suppresses close-in noise and extends the minimum detectable range remarkably.