High efficiency current-mode class-D amplifier with integrated resonator

This paper shows that current mode class-D (CMCD) amplifiers with integrated parallel LC resonator can achieve high efficiency at RF frequencies. In contrast to the conventional class-D amplifier, output shunt capacitance discharge loss is eliminated in a CMCD amplifier topology by satisfying the zero voltage switching (ZVS) condition. To reduce parasitic resistance, bondwires are utilized to implement a high Q inductor in the LC resonator. An experimental CMCD amplifier with collector efficiency of 78.5% at output power of 29.5dBm (0.89W) is demonstrated using GaAs HBTs at 700 MHz.