Resonant Pre-Driver for Switching Amplifier

A switching amplifier comprising:

• a pre-driver amplifier having a pre-driver output;
• a final stage amplifier having a final stage amplifier input and a final stage amplifier output, wherein the final stage amplifier input is coupled to the pre-driver output, and wherein the final stage amplifier input has a final stage amplifier input capacitance, wherein the final stage amplifier is configured to have a charging cycle and a discharging cycle whereby the final stage amplifier input capacitance stores energy during the charging cycle and the final stage amplifier input capacitance discharges energy during the discharging cycle, and
• a resonant circuit element coupled to the final stage amplifier input, wherein the resonant circuit element is configured to receive energy from the final stage amplifier input capacitance during the discharging cycle and supply energy to the final stage amplifier input capacitance during the charging cycle, a capacitance value of the final stage amplifier input capacitance during the discharging cycle being different from a capacitance value of the final stage amplifier input capacitance during the charging cycle,
• wherein the switching amplifier has an operating frequency and wherein component values for the resonant circuit element are chosen to provide a resonant frequency of the resonant circuit element and the final stage amplifier input capacitance at the operating frequency.

A method for amplifying an input signal to an output signal with switching amplification, wherein the method comprises:

• amplifying the input signal with a pre-driver amplification stage to provide a pre-driver output signal;
• coupling the pre-driver output signal to a final amplification stage input of a final amplification stage, wherein the final amplification stage input has a charging cycle and a discharging cycle and wherein the final amplification stage input has a final amplification stage input capacitance configured to have a different capacitance value between the discharging cycle and the charging cycle;
• discharging at least a portion of energy stored in the final amplification input capacitance into a resonant element during the discharging cycle;
• charging the final amplification input capacitance with at least a portion of energy stored in the resonant element during the charging cycle;
• and
• amplifying the final amplification stage input to the output signal with the final amplification stage,
• wherein the final amplification stage comprises one or more transistors configured to be coupled between a supply voltage and a reference potential to simultaneously conduct a same current between the supply voltage and the reference potential.

A method for amplifying an input signal to an output signal with switching amplification, wherein the method comprises:

• amplifying the input signal with a pre-driver amplification stage to provide a pre-driver output signal;
• coupling the pre-driver output signal to a final amplification stage input of a final amplification stage, wherein the final amplification stage input has a charging cycle and a discharging cycle and wherein the final amplification stage input has a final amplification stage input capacitance configured to have a different capacitance value between the discharging cycle and the charging cycle;
• discharging at least a portion of energy stored in the final amplification input capacitance into a resonant element during the discharging cycle;
• charging the final amplification input capacitance with at least a portion of energy stored in the resonant element during the charging cycle;
• and
• amplifying the final amplification stage input to the output signal with the final amplification stage,
• wherein component values of the resonant element are chosen to provide a resonant frequency of the resonant element and the final amplification stage input capacitance at a frequency of the input signal.