A 258-to-280-GHz 100-Gb/s CMOS Transmitter Element in 40-nm CMOS

In order to realize a 300-GHz band 1D phased array transmitter, we present a 300-GHz CMOS transmitter (TX) that has an elongated shape that can be arranged at a narrow pitch and has wide bandwidth. Specifically, by adjusting the gate width of the MOSFETs in an up-conversion mixer, the intermediate frequency (IF) input matching circuit is removed, and a wider bandwidth of the mixer is achieved. Furthermore, by cascading IF amplifier stages, both high gain and broad bandwidth are achieved. The long stubs required to widen the bandwidth of input/output matching circuits are made into loops to reduce the height of the chip. The proposed TX element is fabricated using a 40-nm CMOS process and demonstrated that it achieves a data rate of 100 Gb/s with a 3-dB bandwidth above 22.5 GHz, a center frequency of 268 GHz.