This paper presents the first single-chip direct-conversion 77-85 GHz transceiver fabricated in SiGe HBT technology, intended for Doppler radar and millimeter-wave imaging, particularly within the automotive radar band of 77-81 GHz. A 1.3 mm times 0.9 mm 86-96 GHz receiver is also presented. The transceiver, fabricated in a 130 nm SiGe HBT technology with fT/fMAX of 230/300 GHz, consumes 780 mW, and occupies 1.3 mm times 0.9 mm of die area. Furthermore, it achieves 40 dB conversion gain in the receiver at 82 GHz, a 3 dB bandwidth extending from 77 to 85 GHz at 25degC, and covering the entire 77-81 GHz band up to 100degC, record 3.85 dB DSB noise figure measured at 82 GHz LO and 1 GHz IF, and an IP1dB of -35 dBm. The transmitter provides + 11.5 dBm of saturated output power at 77 GHz, and a divide64 static frequency divider is included on-die. Successful detection of a Doppler shift of 30 Hz at a range of 6 m is shown. The 86-96 GHz receiver achieves 31 dB conversion gain, a 3 dB bandwidth of 10 GHz, and 5.2 dB DSB noise figure at 96 GHz LO and 1 GHz IF, and -99 dBc/Hz phase noise at 1 MHz offset. System-level layout and integration techniques that address the challenges of low-voltage transceiver implementation are also discussed.