Design, implementation and measurement of a 120 GHz 10 Gb/s phase-modulating transmitter in 65 nm LP CMOS

A novel mm-wave phase modulating transmit architecture, capable of achieving data rates as high as 10 Gb/s is presented at 120 GHz. The circuit operates at a frequency of 120 GHz. The modulator consists of a differential branchline coupler and a high speed 4-to-1 analog multiplexer with direct digital input. Both a QPSK as well as a 8QAM constellation are supported. To achieve high output power, a 9-stage power amplifier is designed and connected to the multiplexer output. The complete chip is integrated in a 65 nm low power CMOS technology. Capacitive neutralization is used to achieve high gain and good stability for the MOS devices. Also, various differential transmission line topologies are investigated to achieve high performance in terms of loss and area consumption.