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EFFICIENT METHOD OF OUTPUT POWER CONTROL FOR A RADIO TRANSMITTER

IP.com Disclosure Number: IPCOM000009800D
Publication Date: 2002-Sep-19
Document File: 2 page(s) / 3M

Publishing Venue

The IP.com Prior Art Database

Related People

Russell Archie Morris: AUTHOR [+2]

Abstract

When designing a radio transmitter it is desirable to complete the design in a manner that ensures that the output powyer of the transmitter is constant, independent of variations in operating temperature and across process variations of the main components in the transmit chain. This invention discloses an efficient method for maintaining a constant output power as these parameters vary, and makes as much use as possible of circuitry that is required to provide the basic transmission medium. As a result the method disclosed provides for a cost optimized transmitter architecture.

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TITLE: "EFFICIENT METHOD OF OUTPUT POWER CONTROL FOR A RADIO TRANSMITTER"

INVENTORS: Russell Archie Morris (Opuswave Networks, Inc.)

FILE NO. 99E9508US

By Russell Archie Morris

99E9508US

2. Briefly describe the problem (or problems) which your invention solves:

When designing a radio transmitter it is desirable to complete the design in a manner that ensures that the output powyer of the transmitter is constant, independent of variations in operating temperature and across process variations of the main components in the transmit chain. This invention discloses an efficient method for maintaining a constant output power as these parameters vary, and makes as much use as possible of circuitry that is required to provide the basic transmission medium. As a result the method disclosed provides for a cost optimized transmitter architecture.

3. Describe the prior approaches you know of which add or attempt to solve the s'lame problem(s) most nearly similar to the problem yyour invention solves:

The approaches typically used by those skilled in the art add significant additional circuitry to perform power control, and are typically targeted at adjusting the RF power level using a variable or stepped RF attenuator.

These approaches not only add costly circuitry, but perform the power control at high frequency where signal processing is far from ideal and includes significant parasitic effects. This invention instead adjusts the power level via baseband circuitry, and more specifically circuitry that is required for the basic radio link.

4. Please (describe the physicalstructure of your invention in detail If your invention is a computer program, describe the computer platform for which it was written and an appropriate block diagram or flow chart. Existing drawings can be used instead of a written description.

The physical structure of the invention is shown in the figure below. This diagram shows the transmit chain for a quadrature modulated signal -  from baseband circuitry, through the Digital to Analog Converters (DAC's) , Direct RF Modulator, Transmit Chain, Power Amplifier (?PA) and off to the antenna The diagram also depicts the poweL control loop which uses a power detector (peak detector shown) to sense the Output power and feed back a control signal to adjust the DAC reference currents anyd thereby maintain constant RF output power.

COEDy Modulator Design

Tx DAC

(I)

10 Modulator (Direct Modulation)

Transmit Chain

Baseband Circuitry

RFLO

DAC Iref Control

Transconductance Amplifier

Loop Fitter

Lvref

Difference Amplifier

5. Describe in detail the function or functions performed by the structure (program blocks) you described in paragraph 4 above.

The following is a brief description of each of the function blocks shown in the figure above. For convenience (and to further...