Power and Conjugately Matched High Band UWB Power Amplifier

A common source RF amplifier can be designed to be either power or conjugately matched at the output but not both, since the required load impedances are distinct. In this paper, we have shown that using a drain-gate feedback network brings the power and conjugate match impedances closer together, up to a point where they coincide at a cost of slightly decreased efficiency. We have thoroughly analyzed the output power, return loss, and efficiency tradeoffs and developed a complete design methodology. As a design example, a broadband feedback class-A amplifier has been designed and fabricated in a 130-nm RFCMOS process. The amplifier achieves 7-dBm peak output power and maximum power efficiency of about 20% in the frequency range from 6 to 9 GHz. Input and output return losses are better than 8.5 and 9.5 dB, respectively.