120-GHz-band 20-Gbit/s transmitter and receiver MMICs using quadrature phase shift keying

This paper describes a 120-GHz-band quadrature phase shift keying (QPSK) transmitter and receiver fabricated on microwave monolithic integrated circuits (MMICs). The MMICs were fabricated using 0.1-μm-gate InP HEMTs and can handle 20-Gbit/s data streams. The transmitter MMIC consists of a QPSK modulator with direct modulation, differential amplifiers for data, a power amplifier, and an output-power monitor circuit. A differentially coherent detector, voltage-controlled phase shifter, and low-noise amplifier are monolithically integrated on a receiver MMIC. The QPSK transmitter and receiver MMICs were mounted in WR-8 waveguide modules to evaluate the data transmission performance. The bit error rate (BER) for 22.2-Gbit/s pseudorandom binary sequence (PRBS) 2⁷-1 data is smaller than 10^-10 at a receiver power of -35 dBm.