A SiGe HBT variable gain amplifier with 80 dB control range for applications up to 3 GHz

A variable eain amplifier suitable for wideband applications (up to 3GHz) has been designed and fabricated in a SiGe BiCMOS process with f_T = 49 GHz. Variable gain is achieved with a current steering diflerential cascode cell. The amplifier has B linear-io-dB gain range of 82 dB at 1.85 G H a~nd 65 dB at 2.5 GHZw, hich is the largest control ranee reoorted to date. The amolifrer has a maximum gain of 18.