A new criterion for stability assessment of the microwave pHEMT-based low-noise amplifiers

摘要

At present, the foremost low-noise amplifiers are based on usage of the pseudomorphic high-electron-mobility transistors (pHEMTs). However, in many cases, the amplifiers are often constructed at the limits of absolute stability or even in the region of potential instability because only such solutions give requested circuit properties as a trade-off between the transducer power gain and noise figure. The stability properties are mostly checked by the classical criteria such as the Rollett conditions, μ-factor etc. In the paper, a novel additional very efficient criterion is proposed, finding the most critical couple of poles and evaluating the ratio of imaginary and real part. The efficiency of the method is demonstrated on a low-noise antenna preamplifier for a multi-constellation satellite-navigation receiver based on an ATF-54143 pHEMT.