An 80-Gb/s 300-GHz-Band Single-Chip CMOS Transceiver

A single-chip CMOS transceiver (TRX) capable of wireless data rates up to 80 Gb/s using part of frequencies (252–279 GHz) covered by IEEE Std 802.15.3d is presented. The TRX chip operates in either transmitter (TX) or receiver (RX) mode at frequencies comparable to ${f_{\mathrm {max}}}$ of the NMOSFET. The TX part adopts mixer-last architecture with four-way power combining using a ring circuit called a double-rat-race. The RX part adopts fundamental-mixer-first direct-conversion architecture. In the RX mode, the TX serves as an LO multiplier chain, which conventionally accounted for a significant part of the RX die area. The double-rat-race, having an improved design than the original one, integrates the TX and RX and also rejects unwanted harmonics generated by the frequency-doubler-based upconversion mixer. Low-loss, low-characteristic-impedance transmission lines are used extensively to combat losses. The TRX was fabricated using a 40-nm CMOS process. The saturated output power of the TX is −1.6 dBm at 265.68 GHz. The mean single-sideband noise figure (SSB NF) of the RX is 22.9 dB. The TX mode and the RX mode consume dc power of 890 and 897 mW, respectively. A wireless data rate of 80 Gb/s between a pair of TRX chips is demonstrated with 16QAM over a distance of 3 cm.

I. Introduction

Successful demonstrations of high-speed wireless data transmission using frequencies above 200 GHz [1]–[12] seem to indicate that these subterahertz (sub-THz) frequencies are now becoming a worthy candidate for a post-5G wireless communications platform. A highly relevant wireless standard, IEEE Std 802.15.3d, was established in 2017 [13]. It defines a wireless physical layer that enables data rates up to 100 Gb/s using the lower THz frequency range between 252 and 322 GHz. Notably, 802.15.3d merges 252–275 GHz—already allocated for fixed and mobile communications—with the currently unallocated 275–322 GHz. We will hereafter refer to this frequency band ranging from 252 to 322 GHz as the “300-GHz band.” 802.15.3d stipulates that the 300-GHz band be channelized as shown in Fig. 1. The channel bandwidths (BWs) are all integer multiples of 2.16 GHz in view of other standards, including IEEE Std 802.11ad, that adopt 2.16-GHz-wide channels. It seems reasonable to try to make sub-THz transceivers (TRXs) compliant with 802.15.3d. Fig. 1.

Part of channelization of lower THz frequencies from 252 to 322 GHz defined by IEEE Std 802.15.3d [13].