A W-band SiGe BiCMOS Transmitter Based on K-band Wideband VCO for Radar Applications

This paper presents an 86-97 GHz transmitter (TX) using a wideband voltage-controlled oscillator (VCO) operating in 21.5-26 GHz range and frequency quadrupler (FQ) fabricated in SiGe BiCMOS technology. The VCO implements a self-buffered common-collector Colpitts topology with binary-weighted varactor ladder for low VCO gain ($K_{VCO}$) and wide tuning range. Use of high-Q passive components and low-noise heterojunction bipolar transistors (HBT) results in worst-case phase noise of -92.8 dBc/Hz at 1MHz offset from the carrier. The VCO is loaded by a low-loss transformer that splitts the signal between frequency prescaling and multiplying blocks. The prescaler comprise three divide-by-two circuits (DTC) based on D flip-flops (D-FF) providing adequate feedback signal for an external phase-locked loop (PLL). The multiplying section consists of two cascaded Gilbert-cell frequency doublers driving a W-band power amplifier (PA). The TX achieves 0.2dBm output power at 92GHz and more than -2.8dBm in 86-97 GHz range consuming 60mA from 3.3V supply. The chip occupies 0.755 mm2 silicon area.