A 460-GHz Receiver Using Second-Order Subharmonic Mixer in 65-nm CMOS

This article presents a 460-GHz receiver using a second-order subharmonic mixer (SHM) in a 65-nm CMOS technology. The 460-GHz differential RF to a 60-GHz differential intermediate frequency (IF) second-order SHM is based on a single-balanced topology using a single-ended local oscillator (LO). Proper impedances are provided to the SHM at $f_{\text {RF}} - f_{\text {LO}}$ and $2f_{\text {LO}}$ to avoid the adverse effects of the spurious mixing product and LO harmonic on the mixer performance. A breakout of the SHM integrated with a $\times 2$ LO multiplier chain results in a peak conversion gain (CG) of −18.1 dB at 460 GHz. A 3-dB bandwidth of 16 GHz is also achieved with an externally applied 100-GHz LO signal. By integrating a differential on-chip patch antenna in the receiver, no lossy balun is required in the RF path. The 460-GHz receiver achieves a measured noise figure (NF) of 26 dB at 460 GHz, including the loss of the on-chip patch antenna. The 3-dB bandwidth of the CG is 6.5 GHz when fixing the LO frequency. Compared with the state-of-the-art silicon receivers above 400 GHz, this work achieves excellent NF and bandwidth.