A 4 Gs/s comparator fabricated in an AlGaAs/GaAs heterojunction bipolar process

A comparator circuit fabricated in an AlGaAs/GaAs heterojunction bipolar process is described. Nonlinear current gain, thermal effects, and parasitic base collector resistance have been included in the simulation model. The simulation model has been verified with measured data, which show a good match with data predicted by the simulation. At sampling rates up to 4 Gb/s at full Nyquist input frequency, the applicability of the comparator for high-speed analog-digital converters has been shown. Power consumption and input bias current must be taken into account when using it in high-resolution flash converters.<
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