Current mode class-D power amplifiers for high efficiency RF applications

We show that current mode class-D (CMCD) power amplifiers can achieve high efficiency at RF frequencies. In contrast with conventional voltage-mode class D amplifiers, the CMCD features "zero voltage switching" which eliminates the output capacitance discharge loss. Experimental CMCD amplifiers with 76.3% PAE at 290 mW output and 71.3% PAE at 870 mW output are demonstrated, using GaAs FETs at 900 MHz.