Transmission-line tuned switching power amplifier

An apparatus for amplifying an input signal having a fundamental frequency to develop an output signal with the same frequency at a load, said apparatus comprising:

• a switch having a control terminal for receiving the input signal, said switch responsive to the input signal to turn said switch on and off, said switch further having first and second current flow terminals, said first and second current flow terminals having a low impedance therebetween when said switch is on and having a high impedance therebetween when said switch is off;
• a load network coupled to said switch to deliver the output signal to the load, said load network including a transmission line (TL) of a determined electrical length coupled between said first and second current flow terminals and a parallel capacitor coupled between said first and second current flow terminals to develop a parallel inductance and a parallel capacitance across said switch;
• and
• a DC power source for supplying DC power to said load network and said switch;
• wherein said TL and said parallel capacitor create a transient response across said switch that insures that, as the switch transitions from on to off, the voltage across the first and second terminals remains low until the current through the first and second terminals is substantially zero, and, prior to the switch's transition from off to on, the voltage across the first and second terminals and the voltage time derivative are substantially zero.