Single output stage power amplification for multimode applications

• US 20030073418A1
• Filed: 10/11/2001
• Published: 04/17/2003
• Est. Priority Date: 10/11/2001
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Jorgenson, Jon D., Dening, David, Steel, Victor E.
• Granted Patent: US 6,819,941 B2
• Time in Patent Office: Days
• US Class Current: 455/126
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04B 1/0053 with common antenna for more than one band
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control

Abstract

The present invention eliminates the need for complex impedance networks or parallel amplification stages for multi-mode mobile terminals. A wideband power amplifier is configured to amplify signals in different frequency bands corresponding to different operating modes. The supply voltage of the wideband power amplifier is adjusted in light of the load impedance of radiating circuitry to achieve a desired output power for the respective operating modes.

Claims

1. A radio frequency communication system comprising:

a) radiating circuitry including an antenna and having a load impedance;

b) a wideband power amplifier output stage coupled to the radiating circuitry and adapted to amplify a radio frequency signal in each of a plurality of frequency bands corresponding to a plurality of operating modes;

c) a variable power supply adapted to provide a selected supply voltage for supplying power to the wideband power amplifier output stage responsive to a power control signal; and

d) a control system adapted to generate the power control signal based on a selected one of the plurality of operating modes such that the power delivered to the radiating circuitry for each of the plurality of operating modes from the wideband power amplifier output stage is determined by the selected supply voltage and the load impedance for the frequency band of the selected operating mode.

2. The radio frequency communication system of claim 1 wherein the power level within at least one of the selected operating modes is further controlled by controlling a signal level for the radio frequency signals to be amplified by the wideband power amplifier output stage.

3. The radio frequency communication system of claim 1 wherein the power level within at least one of the selected operating modes is further controlled by further controlling the selected supply voltage.

4. The radio frequency communication system of claim 1 wherein the wideband power amplifier output stage is comprised of transistors configured to operate in saturation when in one of the selected operating modes.

5. The radio frequency communication system of claim 1 wherein the wideband power amplifier output stage is comprised of transistors configured for linear operation when in one of the selected operating modes.

6. The radio frequency communication system of claim 1 wherein the wideband power amplifier output stage is comprised of transistors configured to operate in saturation when in a first of the selected operating modes and for linear operation when in a second of the selected operating modes.

7. The radio frequency communication system of claim 1 further comprising:

a) at least one wideband intermediate amplifier stage coupled in series to the wideband power amplifier output stage; and

b) combining circuitry for passing signals within the frequency band of the selected operating mode from modulation circuitry to the at least one wideband intermediate amplifier stage.

8. The radio frequency communication system of claim 7 wherein the modulation circuitry is adapted to modulate data for transmission using different modulation techniques for the plurality of operating modes.

9. The radio frequency communication system of claim 1 wherein the wideband power amplifier output stage comprises an array of parallel, bipolar transistors wherein the collectors are coupled together to provide an output for driving the radiating circuitry and coupled to the supply voltage via filter circuitry.

10. The radio frequency communication system of claim 9 wherein the filter circuitry is configured to block frequency components corresponding to each of the plurality of frequency bands.

11. The radio frequency communication system of claim 1 further comprising bias circuitry for providing bias to the wideband power amplifier output stage, the bias configured to optimize efficiency of the wideband power amplifier output stage at different supply voltages for each of the plurality of operating modes.

12. The radio frequency communication system of claim 1 wherein the radiating circuitry further comprises a selectable impedance component to adjust the reactance of the load impedance for at least one of the operation modes to optimize signal transmission.

13. The radio frequency communication system of claim 1 wherein the radiating circuitry is configured to provide a first impedance for the load impedance for a first frequency band and a second impedance for the load impedance for a second frequency band.

14. The radio frequency communication system of claim 13 wherein the first and second impedances are approximately the same.

15. A method comprising:

a) amplifying a radio frequency signal in each of a plurality of frequency bands corresponding to a plurality of operating modes with a wideband power amplifier output stage;

b) coupling the amplified radio frequency signal to radiating circuitry having a load impedance for transmission; and

c) providing a selected supply voltage for supplying power to the wideband power amplifier output stage based on a selected one of the plurality of operating modes such that the power delivered to the radiating circuitry for each of the plurality of operating modes from the wideband power amplifier output stage is determined by the selected supply voltage and a load impedance of the radiating circuitry for the frequency band of the selected operating mode.

16. The method of claim 15 wherein a power level within at least one of the selected operating modes is further controlled by controlling a signal level for the radio frequency signals to be amplified by the wideband power amplifier output stage.

17. The method of claim 15 wherein a power level within at least one of the selected operating modes is further controlled by further controlling the selected supply voltage.

18. The method of claim 15 wherein the amplifying step further comprises operating the wideband power amplifier output stage in a saturation region when in one of the selected operating modes.

19. The method of claim 15 wherein the amplifying step further comprises operating the wideband power amplifier output stage in a linear region when in one of the selected operating modes.

20. The method of claim 15 wherein the amplifying step further comprises operating the wideband power amplifier output stage in a saturation region when in a first of the selected operating modes and in a linear region when in a second of the selected operating modes.

21. The method of claim 15 further comprising adjusting a reactance of the load impedance for at least one of the operating modes to optimize signal transmission.

22. The method of claim 15 wherein the radiating circuitry is configured to provide a first impedance for the load impedance for a first frequency band and a second impedance for the load impedance for a second frequency band.

23. The method of claim 22 wherein the first and second impedances are approximately the same.

24. A communication system comprising:

a) a wideband power amplifier output stage for amplifying a radio frequency signal in each of a plurality of frequency bands corresponding to a plurality of operating modes;

b) means for coupling the amplified radio frequency signal to radiating circuitry having a load impedance for transmission; and

c) means for providing a selected supply voltage for supplying power to the wideband power amplifier output stage based on a selected one of the plurality of operating modes such that the power delivered to the radiating circuitry for each of the plurality of operating modes from the wideband power amplifier output stage is determined by the selected supply voltage and a load impedance of radiating circuitry for the frequency band of the selected operating mode.

25. The communication system of claim 24 further comprising means for controlling the power level within at least one of the selected operating modes by controlling a signal level for the radio frequency signals to be amplified by the wideband power amplifier output stage.

26. The communication system of claim 24 further comprising means for controlling the power level within at least one of the selected operating modes by controlling the selected supply voltage.

27. The communication system of claim 24 further comprising means for biasing the wideband power amplifier output stage to operate in a saturation region when in one of the selected operating modes.

28. The communication system of claim 24 further comprising means for biasing the wideband power amplifier output stage to operate in a linear region when in one of the selected operating modes.

29. The communication system of claim 24 further comprising means for biasing the wideband power amplifier output stage to operate in a saturation region when in a first of the selected operating modes and in a linear region when in a second of the selected operating modes.

30. The communication system of claim 24 further comprising means for adjusting a reactance of the load impedance for at least one of the operating modes to optimize signal transmission.