A DC-20-GHz InPHBT balanced analog multiplier for high-data-rate direct-digital modulation and fiber-optic receiver applications

This paper reports on a dc-20-GHz InP heterojunction bipolar transistor (HB T) active mixer, which obtains the highest gain-bandwidth product (GBP) thu s far reported for a direct-coupled analog mixer integrated circuit (IC), T he InP HBT active mixer is based on the Gilbert transconductance multiplier cell and integrates RF, local oscillator, and IF amplifiers. High-speed 70 -GHz f(T) and 160-GHz f(max) InP HBT devices along with microwave matching accounts for its record performance. Operated as a down-converter mixer, th e monolithic microwave integrated circuit achieves an RF bandwidth (BW) fro m dc-20 GHz with 15.3-dB gain and benchmarks a factor of two improvement in GBP over state-of-the-art analog mixer IC's [1]-[9], Operated as an up-con verter, direct-digital modulation of a 2.4-Gb/s 2(31) - 1 pseudorandom bit sequence (PRBS) onto a 20-GHz carrier frequency resulted in a carrier rejec tion of a 28 dB, clock suppression of 45 dBc, and less than a 50-ps demodul ated eye phase jitter. The analog multiplier was also operated as a variabl e gain amplifier, which obtained 20-dB gain with a BW from dc-18 GHz, an th ird-order intercept of 12 dBm, and over 2(5) dB of dynamic range. A single- ended peak-to-peak output voltage of 600 mV was obtained with a +/-35-mV 15 Gb/s 25 - 1 PRBS input demonstrating feasibility for OC-192 fiber-telecomm unication data rates. The InP-based analog multiplier IC is an attractive b uilding block for several wide-band communications such as those employed i n satellites, local multipoint distribution systems, high-speed local area networks, and fiber-optic links.