Method and apparatus for a transceiver having a constant power output
AssigneeAtheros Communications, Inc.
InventorBrian J. Kaczynski
Life of this patent
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Abstract
The present invention includes a transceiver and a method of operating the same that includes in the transmitter a power control circuit that operates on an analog differential signal containing data packets individually. The power control circuit initially transmits a series of data symbols with known values, periodically strobes the transceiver system for correct power levels and incrementally increases the power level of the transceiver until the optimal gain is reached, without exceeding the maximum output power.
Claims33
An upconversion and amplification apparatus for use in a transmitter that provides an amplified differential signal having substantially constant output power and containing, over time, data from a plurality of data packets, each data packet including a plurality of training symbols towards a beginning of the packet, the apparatus comprising:
- a variable gain amplifier having a variable gain, the variable gain amplifier inputting a differential signal and outputting an amplified differential signal;
- a power amplifier electrically coupled to the variable gain amplifier, the power amplifier inputting the differential signal or a signal deriving from the amplified differential signal and outputting a power amplified differential signal having an output power;
- a power detection circuit including a power detector that is coupled to the power amplification stage and provides a detected power signal indicating the output power such that the detected power signal is created at an interval that is at least once per symbol during some of the plurality of training symbols;
- and
- a power control circuit electrically coupled to the power detection circuit, and the variable gain amplifier, the power control circuit:
- increasing the variable gain of the variable gain amplifier in a step increment if the detected power signal, as detected during each of the some of the plurality of training symbols during each packet transmission, is lower than a predetermined power;
- and
- decreasing the variable gain of the variable gain amplifier in a step decrement if conditions require so that the detected power signal will not exceed an output power threshold.
A method of transmitting digital data packets via a CMOS transceiver with a constant output comprising.
- amplifying a first differential analog frequency representation of a first digital data packet containing data values to obtain a first amplified differential analog frequency representation of the first digital data packet, the step of amplifying including amplifying using a variable gain amplifier and amplifying using a power amplifier;
- at each of a first plurality of predetermined intervals when amplifying the first differential analog frequency representation of the first digital data packet, determining whether the output power of the first differential analog frequency representation of the first digital data packet reaches a predetermined reference power;
- and
- if the output power does not reach the predetermined reference power during each of the first plurality of predetermined intervals, then incrementing in step increments a gain of the variable gain amplifier at each of the first plurality of predetermined intervals.
An apparatus for use in a transmitter comprising:
- a variable gain amplifier, the variable gain amplifier including:
- an inductively loaded folded cascode circuit that inputs an input differential signal having a VDD-referenced output level and outputs a current;
- an input current load circuit that inputs the current from the inductively-loaded folded cascode circuit and outputs an output differential signal having a ground-referenced output level;
- a plurality of gain cells, each gain cell coupled to the input current load circuit and receiving the output differential signal, each gain cell comprising two current mirror circuits;
- and
- a plurality of switching circuits, each switching circuit coupled to one of the plurality of gain cells and each switching circuit operating in a positive mode and in a negative mode, the negative mode having an opposite polarity to the positive mode, and wherein the plurality of switching circuits operate to place more of the plurality of gain cells in the positive mode than in the negative mode.
Dependencies are inferred from the claim text.