The maintenance of HPA MMIC´s efficiency for K-band

This paper describes methods of supporting efficiency of an HPA at K band. We designed and fabricated HPA MMIC for K band using UMS 0.25 um GaAs process and then added adaptive biasing circuits for preservation of HPA efficiency. The circuits for maintenance of PAE consist of a directional coupler, a RF detector, a buffer amplifier and a DC-DC convertor. The 8V supplied HPA´s PAE is presented 13.5% at 32.3 dBm but adaptive bias supplied HPA´s PAE is displayed 18.2% at Pout 31.9 dBm. The PAE of adaptive biased HPA increases 4.7% than 8 V supplied HPA. Also, the amplifier PAE is maintained at back off 3.5 dB in CW operation conditions. The MMIC power amplifier and adaptive biasing circuits for HPA MMIC´s efficiency are presented in this paper.