Amplifier bias control circuit

A closed loop feedback controller configured to drive the bias point of a radio frequency amplifier, comprising:

• a resistor coupled in series to the drain of the radio frequency amplifier, wherein the resistor is configured to sense the amplifier's DC bias operating point;
• an instrumentation amplifier coupled in parallel to the resistor and configured to convert the DC bias operating point sensed by the resistor to an analog voltage;
• a comparator configured to provide a logic level output by comparing the output of the instrumentation amplifier with a reference level;
• a digital clock configured to provide a sequence of pulses to a digitally controlled voltage source;
• and
• a digitally controlled voltage source configured to receive the logic level output of the comparator and the sequence of pulses from the digital clock and to drive a voltage output in a direction determined by the logic level output to bias the radio frequency amplifier.

A closed loop feedback controller configured to drive the bias point of a radio frequency amplifier, comprising:

• a current sensing circuit configured to provide an output signal proportional to a DC bias operating point of the radio frequency amplifier;
• an analog-to-digital converter coupled to the current sensing circuit and configured to convert the output signal of the current sensing circuit to a digital signal;
• a processor coupled to the analog-to-digital converter and configured to control a digitally controlled voltage source responsive to the digital signal received from the analog-to-digital converter;
• and
• a digitally controlled voltage source coupled to the processor and having a plurality of programmable data registers to programmably bias a gate of the radio frequency amplifier.

A closed loop feedback controller configured to drive the bias point of a radio frequency amplifier, comprising:

• a resistor coupled in series to the drain of the radio frequency amplifier, and configured to sense the amplifier's DC bias operating point;
• and
• an instrumentation amplifier coupled in parallel to the resistor and configured to convert the DC bias operating point sensed by the resistor to an analog voltage. an analog-to-digital converter coupled to the current sensing circuit and configured to convert the output signal of the current sensing circuit to a digital signal;
• a processor coupled to the analog-to-digital converter and configured to control a digitally controlled voltage source responsive to the digital signal received from the analog-to-digital converter;
• a digitally controlled voltage source coupled to the processor and having a plurality of programmable data registers to programmably bias the gate of the radio frequency amplifier;
• and
• an operational amplifier configured as a buffer and coupled between the digitally controlled voltage source and the gate of the radio frequency amplifier.