InAlAs/InGaAs double heterojunction bipolar transistors with a collector launcher structure for high-speed ECL applications

The authors report the demonstration of high-speed ECL (emitter coupled logic) circuits using InAlAs/InGaAs double-heterojunction bipolar transistors (DHBTs). These DHBTs use a launcher structure in the collector to reduce the collector transit time. The DHBTs achieve the cutoff frequencies of f/sub T/=64 GHz and f/sub max/=54 GHz and hold a breakdown voltage about three times that of conventional InGaAs single-heterojunction bipolar transistors. A 1/4-frequency divider with bilevel ECL gates fabricated using these DHBTs operated at up to 11.9 GHz with a supply voltage of 3.5 V. The total power consumption was 255 mW. The novel collector structure produces high-speed and high-breakdown-voltage DHBTs, enabling high-speed digital applications of InGaAs-based HBTs.<>