Gain-bandwidth tuning techniques for loss-compensated Travelling Wave Amplifiers

This paper presents gain and bandwidth control techniques for wideband loss-compensated Travelling Wave Amplifier (TWAs). The behavior of the distributed amplifiers is tuned acting on the circuit bias in two ways: changing the transistor operation points from saturation to forward active, and tuning the amplifier loss compensation. A tuning range for the gain of 40 dB has been experimentally validated on an existing 0.13 μm SiGe BiCMOS TWA. During the gain tuning the group delay and input and output return losses showed almost no variations over the 170 GHz amplifier bandwidth. Moreover, the presented techniques enabled the control of the upper 3 dB corner frequency. The presented results compare well against the state of the art for variable gain distributed amplifiers (VGDAs) with outstanding bandwidth of operation and gain tuning range.