A 5.8-GHz power amplifier with an on-chip tunable output matching network

The power efficiency of power amplifiers (PAs) at low drive levels can be enhanced if the load impedance presented to the transistors can be adjusted using a tunable output matching network. In this work, a 5.8-GHz PA with an on-chip tunable output matching network on a GaAs 0.15-μm pHEMT process is presented. As opposed to most of the previous work in the literature, the varactor-based continuously tunable matching network presented here is fully-integrated. Moreover, in this work, another PA with a fixed output matching network is fabricated on the same chip with the tunable PA for the purpose of comparison. The measured saturation power levels for both PAs are 22.2 dBm. At the output power level of 17.5 dBm, a 4% PAE improvement is observed. This translates into a 16% reduction in DC power consumption.