CIRCUITS AND METHODS FOR IMPLEMENTING POWER AMPLIFIERS FOR MILLIMETER WAVE APPLICATIONS

摘要

Circuits and methods are provided for implementing highly efficient switch-mode power amplifiers using BJTs (bipolar junction transistors) as active switching devices at millimeter- wave frequencies. For example, a power amplifier circuit (100) includes an active switch device comprising a BJT (bipolar junction transistor) (Tl) and an input network (105), (106) coupled to a base of the BJT (Tl) to drive the active switch device to achieve highly efficient switch-mode (e.g., Class E) operation at millimeter wave frequencies (e.g., 60 GHz). The input network (105), (106), which may be a passive or active driver network, is designed to provide optimal driving conditions. For instance, the input network (105), (106) is designed to present a real input impedance in a range of about 7 Ohms to about 15 Ohms as seen from the base of the active switch device (Tl). Another optimal driving condition includes the input network (105), (106) being designed to provide an asymmetrical drive current to the base of the active switch device (Tl), wherein the negative peak base current exceeds the positive peak base current. Further, the input network is designed to provide an asymmetrical drive base current to the active switch device (Tl) such that the base voltage has a swing that does not exceed about 400 mVpp (millivolts peak-to-peak).