HIGH EFFICIENCY DIGITAL POWER AMPLIFIER

摘要

A digital power amplifier (or power switching amplifier or power switch) (104) for use in a digital transmitter (100) includes a low impedance multi-stage driver circuit (202) having a low impedance pre-driver (208) and a low impedance driver (210). The drive circuit (202) drives a power switch stage (204) having two power transistors (Ql, Q2) configured in a current mode class-D push-pull configuration. Utilization of gallium nitride (GaN) transistors or pseudomorphic high electronic mobility transistors (pHEMT) (or combination thereof) and sizing the transistors progressively larger in the driver (210) than in the pre-driver (208) (at least about 3X) provides a reduction in output impedance of the driver circuit (202) and progressive increase in the power driving capability of the each of the succeeding stages. This allows the use of a power amplifier (102) at higher frequencies without altering or affecting the power efficiency and allows use of a digital power amplifier (104) for the digital transmitter (100).