Optoelectronic Microwave Power Amplifiers

The power amplifiers used in the transmit/receive (TR) modules of future X-band radar systems will be required to be more efficient and compact than currently used circuits. This paper describes a simulation study of optoelectronic (OE) Class AB and Class E microwave power amplifiers based on a novel photoconductive semiconductor switch (PCSS). The simulations show that as the width of the gallium arsenide PCSS is reduced below 1.0 mum its dielectric breakdown field increases significantly, and at 0.1 mum the switch turn-off time is fast enough for 10.0 GHz amplifier operation. The Class AB OE amplifier based on a five-layer PCSS produced approximately 2.0 W of 10.0 GHz output power with approximately 50% efficiency. The Class E OE amplifier based on a single-layer PCSS produced approximately 86 mW output power with 56% efficiency. The Class E OE amplifier needs to be more carefully designed than the Class AB amplifier, but its output microwave waveforms exhibit less distortion.