Power amplifying system with supply and bias enhancements

• US 6,784,748 B1
• Filed: 06/11/2002
• Issued: 08/31/2004
• Est. Priority Date: 02/24/2000
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Rohlfing, Stephan M., Canyon, James C.
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US10/167,530
• Publication Number:
  US 20040164803A1
• Time in Patent Office: 812 Days
• Field of Search: 330/51, 330/285, 330/296, 330/297
• US Class Current: 330/296
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• 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 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 2200/18 the bias of the gate of a FET being controlled by a control signal
• CPC Class Codes: H03F 2200/181 A coil being added in the gate circuit of a FET amplifier stage, e.g. for noise reducing purposes
• CPC Class Codes: H03F 2200/222 A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/318 A matching circuit being used as coupling element between two amplifying stages
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• 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 2200/516 Some amplifier stages of an amplifier use supply voltages of different value
• CPC Class Codes: H03F 2200/555 A voltage generating circuit being realised for biasing different circuit elements
• CPC Class Codes: H03F 2203/7227 the gated amplifier being switched on or off by a switch in the supply circuit of the amplifier
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03G 3/004 Control by varying the supply voltage
• CPC Class Codes: H03G 3/3042 : in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04

Abstract

A radio frequency (RF) power amplifying system. The power amplifying system includes a power controller and power amplifiers comprising power transistors and bias circuitry. The bias circuitry provides current to the base of the one or more power transistors in such as manner as to automatically maintain the power transistors in substantially linear operation throughout the variation in voltage as supplied by the power controller.

Claims

1. A method for operating a power amplifier, comprising the steps of:

providing a radio frequency (RF) transistor with a base terminal of the RF transistor coupled to a bias circuit;

providing a power controller that couples a supply voltage to a collector terminal of the RF transistor, wherein the collector terminal is decoupled from the bias circuit of the RF transistor; and

coupling the bias circuit to a reference voltage that is independent of the supply voltage.

2. The method of claim 1, further comprising the step of monitoring the current draw of the bias circuit with the power controller that is coupling the supply voltage to the collector terminal of the RF transistor.

3. The method of claim 2, further comprising the step of varying the supply voltage of the power controller based on the current draw of the bias circuit.

4. The method of claim 2, further comprising the step of varying the supply voltage of the power controller based on the output power delivered by the power amplifier.

5. The method of claim 4, wherein the output power of the power amplifier is proportional to the current draw of the bias circuit.

6. The method of claim 4, wherein the power controller provides a plurality of output power levels.

7. The method of claim 6, further comprising the step of maintaining a substantially constant bias current to the base terminal of the RF transistor for each output power level delivered by the power amplifier.

8. A method for operating a power amplifier, comprising the steps of:

providing a radio frequency (RF) transistor with a base terminal of the RF transistor coupled to a bias circuit;

providing a collector terminal decoupled from the bias circuit of the RF transistor;

coupling the bias circuit to a reference voltage that is independent of a supply voltage;

coupling the supply voltage to the collector terminal of the RF transistor;

monitoring the current draw of the bias circuit with a power controller that is providing the supply voltage to the collector terminal of the RF transistor;

varying the supply voltage of the power controller based on the current draw of the bias circuit;

varying the supply voltage of the power controller based on the output power delivered by the power amplifier, wherein the output power of the power amplifier is proportional to the current draw of the bias circuit, wherein the power controller provides a plurality of output power levels; and

maintaining a substantially constant bias current to the base terminal of the RF transistor for each output power level delivered by the power amplifier.

9. A method for operating a power amplifier, comprising the steps of:

providing a radio frequency (RF) transistor with a base terminal of the RF transistor coupled to a bias circuit and a collector terminal decoupled from the bias circuit;

coupling the bias circuit to a reference voltage that enables the power amplifier;

coupling the bias circuit and the collector terminal of the RF transistor to a supply voltage; and

automatically varying the bias circuit current to the base of the RF transistor based on the change in the supply voltage, such that a bias point of the RF transistor is automatically adjusted as the supply voltage is varied.

10. The method of claim 9, further comprising the step of providing the supply voltage with a power controller.

11. A power amplifying system comprising:

a power amplifier comprising at least one radio frequency (RF) transistor having a base terminal, a collector terminal, and an emitter terminal;

a bias circuit that couples a reference voltage to the base terminal of the RF transistor and provides a substantially constant current to the base terminal of the RF transistor, wherein the bias circuit is further decoupled from the collector terminal of the RF transistor; and

a power controller that couples a supply voltage to the collector terminal, the supply voltage independent of the reference voltage, wherein a supply voltage provided by the power controller can be applied to the collector terminal of the RF transistor while maintaining substantially linear operation of the power amplifier.

12. The system of claim 11, wherein the power controller is configured to provide a supply voltage that is independent of the reference voltage, such that the supply voltage is coupled to the collector terminal of the RF transistor and said supply voltage is automatically varied as a function of the bias circuit current drawn at the base terminal of the RF transistor.

13. The system of claim 12, wherein the power controller is further configured to monitor the current draw of the bias circuit.

14. The system of claim 12, wherein the power controller is further configured to vary the supply voltage based on the current draw of the bias circuit.

15. The system of claim 13, wherein the power controller is further configured to vary the supply voltage based on the output power delivered by the power amplifier.

16. The system of claim 14, wherein the output power of the power amplifier is proportional to the current draw of the bias circuit.

17. The system of claim 16 wherein the power controller is configured to provide a plurality of output power levels, current sensing, and look-up table functionality.

18. The system of claim 17, wherein the bias circuit is further configured to maintain a substantially constant bias current to the base terminal of the RF transistor for each output power level delivered by the power amplifier.

19. The system of claim 11, further comprising data structures and operating hardware and operating software for a personal communications device.

20. The system of claim 11, wherein the bias circuit further comprises a constant current source and a current mirror circuit.

21. The system of claim 11, wherein the power amplifier further comprises at least one enable pin that is coupled to an enabling input to turn on the power amplifier.

22. The system of claim 11, further comprising a Vmode pin to provide for lower bias voltages to the power amplifier.

23. A power amplifying system comprising:

a power amplifier comprising at least one radio frequency (RF) transistor having a base terminal, a collector terminal, and an emitter terminal;

a bias circuit that couples a reference voltage to the base terminal of the RF transistor and provides a substantially constant current to the base terminal of the RF transistor, wherein the bias circuit is further decoupled from the collector terminal of the RF transistor such that a supply voltage, that is independent of the reference voltage, can be applied to the collector terminal of the RF transistor while maintaining substantially linear operation of the power amplifier;

a power controller that is configured to provide a supply voltage that is independent of the reference voltage, such that the supply voltage is coupled to the collector terminal of the RF transistor and said supply voltage is automatically varied as a function of the bias circuit current drawn at the base terminal of the RF transistor, wherein the power controller is further configured to monitor the current draw of the bias circuit, wherein the power controller is further configured to vary the supply voltage based on the current draw of the bias circuit, wherein the power controller is further configured to vary the supply voltage based on the output power delivered by the power amplifier, wherein the output power of the power amplifier is proportional to the current draw of the bias circuit, wherein the power controller is configured to provide a plurality of output power levels, current sensing, and look-up table functionality, wherein the bias circuit is further configured to maintain a substantially constant bias current to the base terminal of the RF transistor for each output power level delivered by the power amplifier, wherein the bias circuit further comprises a constant current source and a current mirror circuit, wherein the power amplifier further comprises at least one enable pin that is coupled to an enabling input to turn on the power amplifier, wherein the bias circuit further comprises a driver transistor that delivers a current of substantially equal magnitude to the current provided by the combination of a current mirror source and constant current source of the bias circuit;

data structures and operating hardware and operating software for a personal communications device; and

a Vmode pin to provide for lower bias voltages to the power amplifier.

24. A power amplifying system comprising:

a power amplifier comprising at least one radio frequency (RF) transistor having a base terminal, a collector terminal, and an emitter terminal;

a bias circuit that couples an enabling reference voltage to the base terminal of the RF transistor, wherein the bias circuit is decoupled from the collector terminal of the RF transistor; and

a power controller that provides a supply voltage to the bias circuit and to the collector terminal of the RF transistor, such that the bias circuit current to the base of the RF transistor automatically varies based on the change in the supply voltage, such that the bias point of the RF transistor is automatically adjusted as the supply voltage is varied.

25. The power amplifying system of claim 24, wherein the bias circuit receives input from the power controller output, from a reference voltage source independent of the supply voltage, and directly from a battery.

26. The power amplifying system of claim 24, wherein the bias circuit comprises transistors configured as a current mirror.

27. The power amplifying system of claim 24, wherein the supply voltage is varied based on the current consumption of the bias circuit.

28. The power amplifying system of claim 24, wherein the current consumption is proportional to the power output of the power amplifier.

29. The power amplifying system of claim 24, further comprising data structures and operating hardware and operating software for a personal communications device.