Integrated GaN Power Switches for Pulsed PAs and Switching Power Conversion Applications

In this paper we present a description and evaluation of commercial foundry Gallium Nitride (GaN) RF HEMTs as power switches in high frequency switching circuits. The switches are used within the multifunctional blocks for a system-on-chip of the front-end of a pulsed VHF radar. The GaN power switches are evaluated in a voltage mode Class-D (VMCD) RF amplifier and as a DC-DC converter. The power switches and its associated drivers are designed in a 0.25 μm commercially available RF GaN process technology. The efficiency of the circuit when evaluated as a Class D power amplifier (PA) is 74.5% at 250 MHz and delivers an output power of 39.5 dBm. The measured DC-DC converter circuit has an efficiency of over 92.4% at 100 MHz, delivering 40.8 dBm. These are the highest reported efficiencies for the RF PA and the switching modulator at its respective operating frequencies.