Patent ID: 6893101

Claim:
A radio frequency (RF) amplifier circuit comprising a RF device to amplify a RF signal comprising an amplitude-modulated carrier having an amplitude modulation bandwidth, and a bias circuit to bias the RF device, said bias circuit comprising: a bias amplifier to generate a low-impedance bias signal at a bias amplifier output based on a bias reference voltage input to the bias amplifier; a bias current-limiting resistor coupled to the bias amplifier output; a reactive circuit having a first terminal coupled to the bias current-limiting resistor and a second terminal coupled to a bias input of the RF device, said reactive circuit configured to substantially block the RF signal from the bias circuit while simultaneously passing the bias signal from the bias circuit to the RF device; and said bias amplifier comprising an operational amplifier configured to have a desired gain relative to the bias reference voltage and further configured to have an output bandwidth enabling it to quash signal disturbances feeding back from the bias input of the RF device that are not blocked by the reactive circuit and thereby maintain a fixed bias voltage at the bias amplifier output.