Temperature compensation of collector-voltage control RF amplifiers

• US 20090115520A1
• Filed: 12/04/2006
• Published: 05/07/2009
• Est. Priority Date: 12/04/2006
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Ripley, David S., Phillips, Kerry Brent
• Granted Patent: US 7,696,826 B2
• Time in Patent Office: Days
• US Class Current: 330/256
• 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: H03F 1/302 in bipolar transistor amplifiers H03F1/303, H03F1/305, H03F1/307 take precedence
• CPC Class Codes: H03F 1/32 Modifications of amplifiers to reduce non-linear distortion by negative feedback H03F1/34
• CPC Class Codes: H03F 2200/108 A coil being added in the drain circuit of a FET amplifier stage, e.g. for noise reducing purposes
• CPC Class Codes: H03F 2200/15 the supply or bias voltage or current at the drain side of a FET being continuously controlled by a controlling signal
• CPC Class Codes: H03F 2200/447 the amplifier being protected to temperature influence
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/504 the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H03F 2200/78 A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/245 with semiconductor devices only

Abstract

A temperature compensation system for compensating a collector-voltage controlled RF amplifier. To overcome variation that occurs with temperature which can result in signal degradation of the adjacent channel spectrum, a temperature compensated current is utilized to create an offset signal. The offset signal is processed in connection with a control or data signal to generate a temperature compensated voltage source control signal. A differential amplifier may process the data or control signal and the offset signal. The compensated voltage control signal tracks temperature to adapt the applied collector voltage to temperature. This in turn forces the applied collector voltage to vary in response to temperature changes thereby maintaining a constant output power or RF swing. One example environment of use is in an EDGE type GSM system.

Claims

1. A method for temperature compensating an RF amplifier when generating an RF output signal comprising:

providing a control signal to a differential amplifier;

generating a band gap current;

generating a temperature proportional current;

converting the band gap current and the temperature proportional current to an offset voltage;

providing the offset voltage to the differential amplifier;

generating a temperature compensated control signal with the differential amplifier;

generating an applied collector voltage based on the temperature compensated control signal;

applying the applied collector voltage to an output of the RF amplifier to thereby generate a temperature compensated RF output signal.

2. The method of claim 1, wherein the differential amplifier comprises an error amplifier.

3. The method of claim 1, wherein the control signal comprises a data signal.

4. The method of claim 1, wherein the RF output signal is amplitude modulated.

5. The method of claim 1, wherein the applied collector voltage is further supplemented by a network voltage, wherein the network voltage comprise a voltage related to a network resistance, the temperature proportional current, and the band gap current.

6. The method of claim 1, wherein the method of claim 1 is also for reducing the phase distortion in the RF output signal.

7. A system for generating a temperature compensated RF output signal comprising:

a temperature dependent offset signal generator configured to generate an offset signal;

a differential amplifier configured to receive a control signal and the offset signal to thereby generate a variable voltage source control signal;

a variable voltage source configured to generate an applied collector voltage in response to the variable voltage source control signal; and

an RF amplifier configured to receive an RF signal and output an amplified RF signal, wherein the amplitude of the amplified RF signal is dependent on the applied collector voltage and the control signal.

8. The system of claim 7, wherein the control signal represents data.

9. The system of claim 7, wherein the temperature dependent offset signal generator comprise a temperature dependent current source.

10. The system of claim 7, wherein the variable current source comprises a PFET.

11. The system of claim 7, wherein the system comprises an EDGE compliant system.

12. The system of claim 7, further comprising a resistor network configured to convert a temperature compensation current to the offset signal.

13. A system for temperature compensating an amplifier comprising:

a first input configured to receive a band gap current signal;

a second input configured to receive a temperature proportional current signal;

a network configured to combine the band gap current signal and the temperature proportional current signal and create an offset signal;

a differing amplifier configured to generate a control signal;

a voltage control device configured to receive the control signal and thereby generate an amplitude modulation signal which is utilized to amplitude modulate an outgoing signal, wherein the amplitude modulated outgoing signal is temperature compensated due to the temperature proportional current signal.

14. The system of claim 13, wherein the band gap current signal comprises a current signal that is not temperature dependent.

15. The system of claim 13, wherein voltage control device comprises a PFET.

16. The system of claim 13, further comprising an input configured to receive a data signal, wherein the data signal and the offset signal generate the control signal such that the control signal is temperature compensated.

17. The system of claim 13, wherein the network comprises one or more resistors.

18. The system of claim 13, wherein the amplitude modulation signal is combined with an output of an RF amplifier to generate the amplitude modulated outgoing signal.

19. The system of claim 13, wherein the system is configured within a mobile communication device.

20. A method for temperature compensating an RF amplifier comprising:

providing a control signal to a voltage or current dependant signal source;

providing a temperature dependant signal source, which is configured to generate a temperature dependant signal

generating a temperature independent voltage related to the control signal;

generating a temperature dependant signal

adding the temperature dependant signal to the temperature independent signal to create a composite signal;

applying the composite signal to one or more collectors of the RF amplifier to generate a temperature compensated RF output signal.

21. The method of claim 20, wherein the control signal is related to an amplitude or envelope of a data signal.

22. The method of claim 20, temperature dependant signal source comprises a temperature dependant voltage source configured to generate a temperature dependant voltage.

23. The method of claim 20, wherein the composite signal comprises a composite voltage.

24. The method of claim 20, wherein the voltage-controlled voltage source comprises a low drop-out voltage regulator (LDO).

25. The method of claim 24, wherein the LDO comprises of an error amplifier configured in a feedback loop to generate an output voltage dependent upon an input control signal.

26. The method of claim 24, wherein the LDO comprises a feedback network comprised of resistors and offset current or voltage sources which are configured to set the desired relationship between the input control signal and the regulated output voltage.

27. The method of claim 24, wherein The LDO comprises a voltage-controlled current source, configured to provide collector current for the RF amplifier while maintaining a regulated collector voltage.