An AlGaAs/GaAs Heterojunction Bipolar Transistor Decision Circuit.

This paper describes an AlGaAs/GaAs HBT circuit designed and characterized as a decision circuit for applications in optical communications. The circuits were designed using 3.5micron emitter width, 27 GHz f sub T devices and conservative design rules. The maximum bit rate for a BER of 1 X 10 sup -9 was 4.2 Gb/s in an ECL configuration. At 2.0 Gb/s, the clock phase margin was 240 degrees. Computer simulations indicate that with minor circuit modifications, maximum bit rate can be extended to above 6 Gb/s in the current technology.