Analysis of the Baseband Termination of High Power RF Transistors

RF Pre-Matching of High Power Transistors involves considerations of impedance matching, RF Bandwidth, phase characteristics as well as physical realization. Due to the increase in signal bandwidth requirements of next generation applications, it has become necessary to incorporate baseband impedance circuits to ensure the power transistor is capable of amplifying these signals with minimum distortion as well as correct within specifications using digital predistortion systems. In this paper we analyze the baseband response of a widely used pre matching topology for RF Power Transistors as well as propose and analyze modifications that allow for improved large signal bandwidth operation. The results show than an ACLR improvement of approximately 10dB resulted from the addition of an integrated bias network with damping resistance using the same DPD complexity.