Continuous closed-loop power control system including modulation injection in a wireless transceiver power amplifier
View Patent ↗A single continuous closed-loop power control feedback system provides seamless power control for a power amplifier and also enables an AM signal to be injected into the power amplifier through the power amplifiers' control port. The AM signal is developed by an I/Q modulator and supplied to a comparator located in the power control loop. By using leakage from the power amplifier as feedback to a phase locked loop during initial power amplifier power ramp-up, the single continuous closed-loop power control system provides continuous feedback to the phase locked loop during the entire power amplification ramp-up period and eliminates the need for multiple feedback loops.
1. A power amplifier control circuit, comprising:
a power amplifier;
a power control loop coupled to the power amplifier; and
a phase locked loop coupled to the power control loop, where the power control loop provides a feedback signal to the phase locked loop, the feedback signal derived using leakage from the power amplifier during a time when the power amplifier is not operating.
2. The circuit of claim 1 , wherein the power control loop provides a feedback signal to the phase locked loop, the feedback signal derived from the output power of the power amplifier during a time when the power amplifier is operating.
3. A method for operating a power amplifier, the method comprising the steps of:
providing a power amplifier and a power control loop;
developing a feedback signal in the power control loop; and
providing the feedback signal to a phase locked loop, the feedback signal derived using leakage from the power amplifier during a time when the power amplifier is not operating.
4. The method of claim 3 , further comprising the step of deriving the feedback signal from the output power of the power amplifier during a time when the power amplifier is operating.
5. A computer readable medium having a program for operating a power amplifier, the program comprising logic for performing the steps of:
providing a power amplifier and a power control loop;
developing a feedback signal in the power control loop; and
providing the feedback signal to a phase locked loop, the feedback signal derived using leakage from the power amplifier during a time when the power amplifier is not operating.
6. The program of claim 5 , further comprising logic for performing the step of deriving the feedback signal from the output power of the power amplifier during a time when the power amplifier is operating.