Gain Control for Linear Radio Freqency Power Amplifiers

• US 20100007414A1
• Filed: 07/08/2009
• Published: 01/14/2010
• Est. Priority Date: 07/08/2008
• Status: Active Grant

• Current Assignee: SIGE Semiconductor Incorporated (Skyworks Solutions Incorporated)
• Original Assignee: SIGE Semiconductor Incorporated (Skyworks Solutions Incorporated)
• Inventors: Whittaker, Edward J., Searle, Kenneth
• Granted Patent: US 7,969,240 B2
• Time in Patent Office: Days
• US Class Current: 330/127
• CPC Class Codes: H03F 1/30 Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in differential amplifiers H03F3/45479
• CPC Class Codes: H03G 3/007 Control dependent on the supply voltage

Abstract

A bias control circuit is provided comprising an input port for receiving a signal indicative of an amplitude of a supply voltage provided to a multi stage power amplifier circuit. Electronic circuitry, electrically coupled to the input port, generates a bias control signal in dependence upon the signal indicative of a supply voltage for provision to a first stage power amplifier of the multi stage power amplifier circuit. The bias control signal is generated such that a gain change of the multi stage power amplifier circuit due to a supply voltage change is substantially compensated.

Claims

1. A bias control circuit comprising:

an input port for receiving a signal indicative of an amplitude of a supply voltage, the supply voltage for being provided to a multi stage power amplifier circuit;

electronic circuitry electrically coupled to the input port, the electronic circuitry for generating, in dependence upon the signal indicative of a supply voltage, a bias control signal for provision to a first stage power amplifier of the multi stage power amplifier circuit, the bias control signal being generated such that a gain change of the multi stage power amplifier circuit due to a supply voltage change is substantially compensated; and

,

an output port electrically coupled to the electronic circuitry, the output port for being electrically coupled to a bias port of the first stage power amplifier and for providing the bias control signal thereto.

2. A bias control circuit as defined in claim 1 comprising:

a second input port electrically coupled to the electronic circuitry for receiving a current signal.

3. A bias control circuit as defined in claim 2 comprising:

a proportional to absolute temperature (PTAT) current source electrically coupled to the second input port.

4. A bias control circuit as defined in claim 2 wherein the electronic circuitry comprises a multiplier for generating the bias control signal in dependence upon the signal indicative of a supply voltage and the current signal.

5. A bias control circuit as defined in claims 1 comprising:

a current source; and

,

output electronic circuitry disposed between the electronic circuitry and the output port and for being electrically coupled to the current source, the output electronic circuitry for receiving a supply voltage independent current from the current source and for adding the same to the bias control signal.

6. A bias control circuit as defined in claim 5 comprising:

a digital to analog converter electrically coupled to the output electronic circuitry and for being electrically coupled to the current source, the digital to analog converter for adjusting a magnitude of the supply voltage independent current in dependence upon a digital control signal.

7. A bias control circuit as defined in claim 5 wherein the current source is a proportional to absolute temperature (PTAT) current source for providing the supply voltage independent current.

8. A bias control circuit as defined in claim 1 comprising:

a digital to analog converter disposed between the electronic circuitry and the output port, the digital to analog converter for adjusting a magnitude of the bias control signal in dependence upon a digital control signal.

9. A bias control circuit as defined in claim 8 comprising:

a current source; and

,

output electronic circuitry disposed between the digital to analog converter and the output port and for being electrically coupled to the current source, the output electronic circuitry for receiving a supply voltage independent current from the current source and for adding the same to the bias control signal.

10. A bias control circuit as defined in claim 9 comprising:

a second digital to analog converter electrically coupled to the output electronic circuitry and for being electrically coupled to the current source, the second digital to analog converter for adjusting a magnitude of the supply voltage independent current in dependence upon a second digital control signal.

11. A bias control circuit as defined in claim 9 wherein the current source is a proportional to absolute temperature (PTAT) current source for providing the supply voltage independent current.

12. A method comprising:

receiving a signal indicative of an amplitude of a supply voltage, the supply voltage for being provided to a multi stage power amplifier circuit;

generating a bias control signal in dependence upon the signal indicative of a supply voltage, the bias control signal for provision to a first stage power amplifier of the multi stage power amplifier circuit, the bias control signal being generated such that a gain change of the multi stage power amplifier circuit due to a supply voltage change is substantially compensated; and

,

providing the bias control signal to the first stage power amplifier.

13. A method as defined in claim 12 wherein the bias control signal is generated such that it is inversely proportional to the supply voltage change.

14. A method as defined in claim 13 wherein the bias control signal is determined based on a mathematical function.

15. A method as defined in claim 12 wherein the signal indicative of a supply voltage is a current signal proportional to the amplitude of the supply voltage.

16. A method as defined in claim 15 comprising:

receiving a second current signal; and

,

multiplying the second current signal with the inverse of the current signal proportional to the supply voltage for generating the bias control signal as a bias current signal.

17. A method as defined in claim 16 wherein the second current signal is a proportional to absolute temperature current signal.

18. A method as defined in claim 16 comprising:

adding a supply voltage independent current to the bias current.

19. A method as defined in claim 18 comprising:

adjusting a magnitude of the supply voltage independent current.

20. A method as defined in claim 18 wherein the supply voltage independent current is a proportional to absolute temperature current signal.

21. A method as defined in claim 16 comprising:

adjusting a magnitude of the bias current signal.

22. A method as defined in claim 21 comprising:

adding a supply voltage independent current to the bias current signal.

23. A method as defined in claim 22 comprising:

adjusting a magnitude of the supply voltage independent current.

24. A method as defined in claim 22 wherein the supply voltage independent current is a proportional to absolute temperature current signal.

25. A multi stage power amplifier circuit comprising:

an input port for receiving a radio frequency signal;

a plurality of power amplifiers for successively amplifying the radio frequency signal, a first power amplifier being connected to the input port for receiving the radio frequency signal and a last power amplifier being connected to an output port for providing an amplified radio frequency signal;

supply circuitry connected to each of the power amplifiers for providing a supply voltage;

a sensor for sensing the supply voltage and for providing a signal indicative of an amplitude of the supply voltage; and

,

electronic control circuitry connected to the sensor and to a bias port of the first power amplifier, the electronic control circuitry for generating a bias control signal in dependence upon the signal indicative of a supply voltage for provision to the first power amplifier, the bias control signal being generated such that a gain change of the plurality of power amplifiers due to a supply voltage change is substantially compensated.

26. A multi stage power amplifier circuit as defined in claim 25 comprising:

a proportional to absolute temperature (PTAT) current source connected to the electronic circuitry, and wherein the electronic circuitry comprises a multiplier for generating the bias control signal in dependence upon the signal indicative of a supply voltage and a current signal received from the proportional to absolute temperature current source.

27. A multi stage power amplifier circuit as defined in claim 26 comprising:

a first digital to analog converter disposed between the electronic circuitry and the bias port, the digital to analog converter for adjusting a magnitude of the bias control signal in dependence upon a first digital control signal; and

,

a second digital to analog converter electrically coupled to a node disposed between the first digital to analog converter and the bias port and electrically coupled to one of the proportional to absolute temperature current source and a second other proportional to absolute temperature current source, the second digital to analog converter for receiving a supply voltage independent current and for adjusting a magnitude of the same in dependence upon a second digital control signal.

28. A storage medium having stored thereon executable commands for execution on a processor, the executable commands for when executed resulting in an electronic circuit design comprising:

an input port for receiving a signal indicative of an amplitude of a supply voltage, the supply voltage for being provided to a multi stage power amplifier circuit;

electronic circuitry connected to the input port, the electronic circuitry for generating a bias control signal in dependence upon the signal indicative of a supply voltage for provision to a first stage power amplifier of the multi stage power amplifier circuit, the bias control signal being generated such that a gain change of the multi stage power amplifier circuit due to a supply voltage change is substantially compensated; and

,

an output port connected to the electronic circuitry, the output port for being connected to a bias port of the first stage power amplifier.