A Broadband 77/79 GHz Transmitter With Dual VCOs and Third Harmonic Signal Extraction in a 28 nm CMOS Technology

A broadband 77/79 GHz transmitter (TX) front-end for automotive long range radar (LRR) and short range radar (SRR) applications is presented in this paper. To achieve the best system performance one new TX architecture with two specifically designed voltage controlled oscillators (VCOs) is implemented in a 28 nm CMOS technology. Furthermore, the degradation of the VCO phase noise due to the TX integration is analyzed in detail and solutions to minimize the impacts are proposed and verified. Experimental results of a 20 GHz push-push VCO1 measured at the 77 GHz TX output show a continuous tuning range of 4.75 GHz, a coarse tuning range of 3.2 GHz and an average phase noise of −100 dBc/Hz @ 1 MHz, while a 26 GHz VCO2 with third harmonic signal extraction achieves a continuous and coarse tuning range of 7.5 GHz and 4.2 GHz with an average phase noise of −96 dBc/Hz @ 1 MHz at 79 GHz TX output. Moreover, a record pushing performance of $\rm {<\!\pm }$ 100 MHz/V at 77/79 GHz TX output has been achieved according to the authors’ best knowledge. The whole TX chip consumes about 860 mW from a single 2.1 V supply while providing more than 16 dBm output power over the whole frequency band.