Patent ID: 8208878

Claim:
An amplitude modulated amplifier for amplifying a radio frequency (RF) signal, the amplifier comprising: four selectably controllable transistors arranged to receive power from a direct current (DC) power supply to amplify the signal, the transistors configured in a bridge configuration with a first and a second transistor coupled between the DC power supply and an antenna having a short electrical length compared to a wavelength of a transmitted signal, and with a third and a fourth transistor coupled between the antenna and ground in an ‘H’ configuration, each transistor having a gate input to determine the state of the transistor between an on state and an off state; four diodes each associated with a different transistor of the four transistors and forward biased from a source to a drain of each transistor, forming a bridge rectifier; and drive logic for controlling each of the four transistors from an open state to a closed amplifying state based on external input, wherein the drive logic is selectable from a driving state to a damping state of the amplifier by switching transistors to recover power from the antenna when an impedance state of the antenna is negative, and to deliver the recovered power to the DC power supply.