A 70 GHz Bidirectional Front-End for a Half-Duplex Transceiver in 90-nm SiGe BiCMOS

This paper presents a 70 GHz bidirectional front-end transceiver circuit in a 90-nm SiGe BiCMOS process. The design consists of a bidirectional power amplifier/low-noise amplifier (PALNA) and a passive mixer. Isolation between the transmitter (TX) and receiver (RX) is achieved with a passive impedance transformation network, eliminating the need for a high frequency transmit/receive switch. Measurement results show the transmitter has a peak output power of 7.2 dBm and a peak conversion gain of 14.5 dB while nominally consumes 47 mA from a 1.8 V supply. The receiver has a peak conversion gain of 9.9 dB and a minimum noise figure of 8.6 dB with nominal current consumption of 18 mA from a 1.5 V supply. This switchless bidirectional front-end is suitable for a half-duplex system with shared TX/RX antenna such as a pulse-compression range sensor or a time-division duplexing (TDD) point-to-point communication system in E-band.