Distortion control feedback loop utilizing a non-linear transfer function generator to compensate for non-linearities in a transmitter circuit

• US 6,321,072 B1
• Filed: 08/31/1998
• Issued: 11/20/2001
• Est. Priority Date: 08/31/1998
• Status: Expired due to Term

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Cipriani, Stefano, Carpineto, Lorenzo, Takeshian, Anthony A.
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): Corsaro, Nick
• Application Number:
  US09/144,404
• Time in Patent Office: 1,177 Days
• Field of Search: 455/126, 455/127, 455/63, 455/91
• US Class Current: 455/126
• CPC Class Codes: H03F 1/3276 using the nonlinearity inherent to components, e.g. a diode
• CPC Class Codes: H03F 1/34 Negative-feedback-circuit arrangements with or without positive feedback H03F1/02 - H03F1/30, H03F1/38 - H03F1/50, H03F3/50 take precedence ; for rejection of common mode signals H03F3/45479
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 2001/0433 with linearisation using feedback

Abstract

A transfer function generator provides the ability to provide a non-linear response in a feedback loop to compensate for non-linearities introduced elsewhere in the system. The transfer function generator includes a non-linear function generator configured to provide an output current that is a non-linear function of an input signal representing an error to be corrected. The transfer function generator can also include a linear function generator configure to provide a linear output current as a function of an input current representing the error corrected. Tuning devices can be provided to adjust the turn-on level of the non-linear function generator and the output level of the linear function generator to allow the transfer function generator flexibility in implementation.

Claims

1. A wireless communication device, comprising:

a power amplifier configured to amplify a signal for transmission by an antenna over a communications channel;

a power level sensor configured to sense the power level radiated from the antenna;

a comparator configured to compare the power level sensed by said power level sensor and a desired output power level and to provide an output indicating the difference between the two;

an integrator configured to integrate the output from said comparator to provide an output indicating an error level; and

a transfer function generator, comprising;

a non-linear function generator configured to provide an output that is a non-linear function of an input representing the output from said integrator,

a linear function generator configured to provide a linear output as a function of an input representing the output from said integrator,

a junction configured to combine said non-linear output with said linear output;

a first tuning device to control turning on said non-linear function generator; and

a second tuning device to control the output of said linear function generator;

wherein said transfer function generator is configured to provide a non-linear response to the error signal generated by the integrator to compensate for non-linearity introduced elsewhere in the communication device.

2. The wireless communication device of claim 1, wherein said first and second tuning devices are variable resistors.

3. A wireless communication device, comprising:

a power amplifier configured to amplify a signal for transmission by an antenna over a communications channel;

a power level sensor configured to sense the power level radiated from the antenna;

a comparator configured to compare the power level sensed by said power level sensor and a desired output power level and to provide an output indicating the difference between the two;

an integrator configured to integrate the level output from said comparator to provide an output indicating an error level;

a transfer function generator, comprising;

a non-linear function generator configured to provide an output that is a non-linear function of an input representing the output from said integrator,

a linear function generator configured to provide a linear output as a function of an input representing the output from said integrator, and

a junction configured to combine said non-linear output current with said linear output circuitry for providing a signal derived from an output of said transfer function generator to control input of said power amplifier;

wherein said transfer function generator is configured to provide a non-linear response to the error signal generated by the integrator to compensate for non-linearity introduced elsewhere in the communication device.

4. A wireless communication device, comprising:

a power amplifier configured to amplify a signal for transmission by an antenna over a communications channel;

a power level sensor configured to sense the power level radiated from the antenna;

a comparator configured to compare the power level sensed by said power level sensor and a desired output power level and to provide an output indicating the difference between the two;

an integrator configured to integrate the output from said comparator to provide an output indicating an error level; and

a transfer function generator, comprising;

a non-linear function generator configured to provide an output that is a non-linear function of an input representing the output from said integrator,

a linear function generator configured to provide a linear output as a function of an input representing the output from said integrator, and

a junction configured to combine said non-linear output with said linear output;

wherein said transfer function generator is configured to provide a non-linear response to the error signal generated by the integrator to compensate for non-linearity introduced elsewhere in the communication device.

5. A wireless communication device, comprising:

a power amplifier configured to amplify a signal for transmission by an antenna over a communications channel;

a power level sensor configured to sense the power level radiated from the antenna;

a comparator configured to compare the power level sensed by said power level sensor and a desired output power level and to provide an output indicating the difference between the two;

an integrator configured to integrate the output from said comparator to provide an output indicating an error level;

a transfer function generator, comprising;

a non-linear function generator configured to provide, when said power amplifier is in its non-linear region, an output that is a non-linear function of an input representing the output from said integrator;

a linear function generator configured to provide, when said power amplifier is in its linear region, a linear output as a function of an input representing the voltage output from said integrator; and

a junction configured to combine said non-linear output with said linear output;

a first tuning device to control the amount of input needed to turn on said non-linear function generator; and

a second tuning device to control the output level of said linear function generator; and

wherein said transfer function generator is configured to provide a non-linear response to the error signal generated by the integrator to compensate for non-linearity introduced elsewhere in the communication device.

6. The wireless communication device of claim 5, wherein said first and second tuning devices are variable resistors.

7. The wireless communication device of claim 5, further comprising:

a voltage to current converter, configured to convert an output voltage of said integrator into a current; and

a current to voltage converter configured to convert a current output from said transfer function generator to a voltage level and to provide said voltage level to control pins of said power amplifier.

8. The wireless communication device of claim 5, further comprising a voltage to current converter, configured to convert a differential voltage into a current for input to said non-linear function generator.