Digital DC correction circuit for a linear transmitter
AssigneeMotorola, Inc.
InventorsMichael H. Baker, Paul H. Gailus, William J. Turney, Lawrence F. Cygan
Life of this patent
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Abstract
An amplifier structure (200) includes a main amplifier loop (203) for efficiently amplifying an input signal at a power amplifier (228) coupled to a load susceptible to impedance variations. The amplifier structure (200) includes a DC correction circuit (214) for detecting and correcting misadjustments in the amplifier (200) in order to eliminate DC offset associated therewith.
Claims8
A radio frequency (RF) amplifier circuit coupled to a load, comprising:
- a main amplifier loop capable of stabilizing an amplifier having a drive signal, without using an isolator;
- and
- an auxiliary loop coupled to the main amplifier loop and receiving a sample of the drive signal, the auxiliary loop comprising:
- an adapter circuit for adapting the amplifier to changes in the impedance of the load, the adapter circuit having a Direct Current (DC) correction circuit for minimizing DC offsets in the main amplifier loop, the adapter circuit comprising:
- a quadrant detector;
- a gain detector, and
- a phase detector to determine incremental DC corrections in order to minimize DC offsets in the main amplifier loop.
A method for providing a linear transmitter, comprising:
- providing an amplifier feedback loop for amplifying a signal;
- detecting the magnitude of the signal;
- establishing performance parameters for the amplifier feedback loop;
- directing an adapter to alter the performance of the amplifier feedback loop when the magnitude of the signal is within a threshold;
- detecting DC offsets in the amplifier feedback loop;
- correcting DC offsets in the amplifier feedback loop;
- and
- adjusting the amplitude of the amplifier feedback loop to compensate for phase changes.
A method for providing a linear transmitter, comprising:
- providing an amplifier feedback loop for amplifying a signal;
- detecting the magnitude of the signal;
- establishing performance parameters for the amplifier feedback loop including calibrating the amplitude and phase of the linear transmitter;
- directing an adapter to alter the performance of the amplifier feedback loop when the magnitude of the signal is within a threshold;
- detecting DC offsets in the amplifier feedback loop;
- and
- correcting DC offsets in the amplifier feedback loop.
A method for minimizing performance degradation of a linear transmitter in the presence of antenna interferences, comprising:
- providing a signal path including an amplifier closed loop;
- coupling a first sample from the signal path to an automatic gain control (AGC);
- coupling a second sample from the signal path to establish a first and a second time window;
- linearly adapting the amplifier closed loop to operate optimally in the first time window including adapting the amplifier closed loop during a third time window to provide for optimum operation during the first time window;
- directing the amplifier closed loop to operate with a predetermined amount of compression in the second time window;
- detecting misadjustments in the amplifier closed loop;
- and
- correcting the misadjustments by eliminating DC offset associated with the amplifier closed loop adapting the amplifier closed loop.
A method for minimizing performance degradation of a linear transmitter in the presence of antenna interferences, comprising:
- providing a signal path including an amplifier closed loop;
- coupling a first sample from the signal path to an automatic gain control (AGC);
- coupling a second sample from the signal path to establish a first and a second time window;
- linearly adapting the amplifier closed loop to operate optimally in the first time window;
- directing the amplifier closed loop during a third time window to operate with a predetermined amount of compression in the second time window;
- detecting misadjustments in the amplifier closed loop and
- correcting the misadjustments by eliminating DC offset associated with the amplifier closed loop.
Dependencies are inferred from the claim text.