A SiGe 8-channel comparator for application in a synthetic aperture radiometer

We present a high-speed low-power 8-channel comparator tailored for the application of sampling antenna signals in a cross-correlator system for space-borne synthetic aperture radiometer instruments. Features like clock return path, perchannel offset calibration and bias current tuning make the comparator adaptable and gives the possibility to adjust the comparator for low power consumption, while keeping performance within the requirements of the cross-correlator system. The comparator has been implemented and fabricated in a 130-nm SiGe BiCMOS process. Measurements show that the comparator can perform sampling at a rate of 4.5 GS/s with a power consumption of 48 mW/channel or 1 GS/s with a power consumption of 17 mW/channel.