Frequency-agile class-D power amplifier

The electronically tuned class-D power amplifier (PA) addresses the simultaneous needs for efficiency and frequency agility. The PA is based upon broadband transformer-coupled topology and uses a MOSFET operating in class D to deliver the maximum output power for given ratings. The output filter is a T network that provides a high impedance to and attenuation of the harmonics. The components of the output filter are bias-tuned inductors of a proprietary design and a voltage-variable capacitor implemented from a bank of high-voltage MOSFETs. The use of electronically tuned components allows the PA to be tuned and operated efficiently over a wide range of frequencies without band-switching.