Compact broadband amplifiers with up to 105 GHz bandwidth in SiGe BiCMOS

In this paper the design and measurements of a single-ended and a fully differential broadband amplifier are presented. The amplifiers are based on a lumped circuit design topology and are highly compact with an active chip area of around 0.02mm
²
. The amplifiers are fabricated in a 0.13-μm SiGe BiCMOS HBT technology. Wide bandwidth is achieved with a common-base input stage and an output cascode stage buffered with emitter followers. A 3-dB bandwidth of around 91 GHz and 105 GHz, and a small-signal gain of 13 dB and 12 dB are achieved for the single-ended and the differential-ended amplifiers, respectively. The differential-ended amplifier shows a superior performance with an input return loss greater than 10 dB from DC-110 GHz, ±1 dB in-band gain ripple and a low group delay variation of ±6 psec. Large signal measurements show a single-ended saturated power of around 2.8 dBm.