Method for controlling the output power of digital cellular telephones
AssigneeHughes Aircraft Company
InventorLanh T. Trinh
Life of this patent
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Abstract
A controlled power amplifier system (211) wherein a sample (225) of the output power level of an on/off switched power amplifier (215) is compared with a reference signal (227) to produce a power level control signal (275) that controls the output power level of the power amplifier (215). When the power amplifier (215) is switched off, the control signal (275) is maintained at the level it had just prior to the transition from an on to an off state. The switching is performed offset from the ends of each switched power amplifier pulse envelope to allow the pulse amplitude to be leveled in the center of the pulse and yet allow the pulse rise and fall times of the pulse envelope to follow the power amplifier input.
Claims15
A controlled power amplifier system comprising:
- a power amplifier for producing an amplified power output signal;
- an output sampler in communication with the amplified power output signal for producing a power level signal representative of the amplified power output signal power level;
- a comparator for comparing the power level signal to a reference power level and producing an error signal in response thereto;
- a power level controller in communication with the comparator for alternately tracking the error signal in a tracking mode and holding a received error signal in a hold mode, the controller also controlling the amplified power output signal power level in response to the tracked or held error signal respectively;
- a system controller for switching the power amplifier between an active state and an inactive state;
- and
- a track/hold circuit in communication with the system controller for detecting when the power amplifier is switched between the active and inactive states and in communication with the power level controller for switching the power level controller between the tracking mode and the hold mode, the circuit switching the power level controller to the tracking mode at a first predetermined time interval after the power amplifier is switched to the active state and switching the power level controller to the hold mode at a second predetermined time interval before the power amplifier is switched to the inactive state.
A method for controlling the output level of a power amplifier which is switched between active and inactive states comprising:
- sampling the power amplifier output signal and producing a power level signal representative of the power amplifier output signal power level;
- comparing the power level signal to a reference power level and producing an error signal in response thereto;
- alternately tracking the error signal in a tracking mode and holding a received error signal in a hold mode of a power level controller and controlling the power amplifier output signal power level in response to the tracked or held error signal respectively;
- detecting when the power amplifier is switched between the active and inactive states and switching the power level controller between the tracking mode and the hold mode, the switching of the power level controller to the tracking mode being done at a first predetermined time interval after the power amplifier is switched to the active state and the switching of the power level controller to the hold mode being done at a second predetermined time interval before the power amplifier is switched to the inactive state.
Dependencies are inferred from the claim text.