System for regulating the power output of and linearizing the transmission signal from a radio transmitter

• US 5,819,165 A
• Filed: 06/27/1997
• Issued: 10/06/1998
• Est. Priority Date: 11/14/1994
• Status: Expired due to Term

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Vuolteenaho, Merja, Hulkko, Jaakko
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/884,114
• Time in Patent Office: 466 Days
• Field of Search: 455/82, 455/83, 455/84, 455/85, 455/86, 455/87, 455/78, 455/115, 455/116, 455/126, 455/127, 455/275, 455/67.4
• US Class Current: 455/126
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

The invention is based on utilizing the receiver of a radio device to detect measured quantities related to a transmission signal. In the power regulating method according to the present invention, which is based on a power regulating loop, transmission power is detected in the receiver of the radio device. Part of the transmission signal (f_TX) is input to the carrier frequency part of the signal path of the receiver by and detected. A signal that is proportional to the power level is produced by a RSSI detector of the receiver, for example. The same circuit can also be utilized in the linearization of a transmission signal based on a closed loop by means of predistortion. Both the power regulation method and the linearization method can be applied in radio telephone systems based on both time-division and continuous transmission and reception.

Claims

1. A method for regulating the power output of a transmitter of a radio device having a transmitter and a receiver, comprising the steps of:

providing an adjustable amplifier in the signal path of the transmitter;

providing an amplified carrier frequency transmission signal from the transmitter to be transmitted by the radio device;

transmitting part of said amplified carrier frequency transmission signal from the transmitter from the radio device and

inputting part of said amplified carrier frequency transmission signal from the transmitter to the signal path of the receiver;

detecting a signal proportional to the transmitter output power in the receiver;

providing a reference signal;

producing a control signal which is proportional to the difference between said reference signal and said detected proportional signal; and

applying said control signal to said adjustable amplifier, wherein the output of said adjustable amplifier is controlled.

2. A method as in claim 1 wherein the step of detecting a signal proportional to said transmitter output comprises the additional steps of:

providing a second adjustable amplifier in the signal path of the receiver; and

providing a second control signal to said second adjustable amplifier, wherein the output of said second adjustable amplifier is constant, said second control signal being proportional to said transmitter output.

3. A method as in claim 1 wherein the step of detecting a signal proportional to the transmitter output power further comprises providing a received signal strength indicator signal of the receiver of the radio device.

4. A method as in claim 1 wherein the step of producing a control signal comprises the initial step of providing a signal processing unit with said detected proportional said signal processing unit calculates said control signal.

5. A method as in claim 1 wherein the step of detecting a signal proportional to said transmitter output power comprises the initial step of detecting I and Q components of a quadrature modulated transmission signal.

6. A method as in claim 1 wherein the step of inputting part of said amplified carrier frequency transmission signal from the transmitter to the receiver of the radio device comprises the step of inputting said transmission signal to the carrier frequency portion of the signal path of the receiver.

7. A method for linearizing a transmission signal of a radio device having a transmitter and a receiver, comprising the steps of:

providing an amplified carrier frequency transmission signal from the transmitter to be transmitted by the radio device;

transmitting part of said amplified carrier frequency transmission signal from the transmitter from the radio device and

inputting part of said amplified carrier frequency transmission signal from the transmitter to the receiver of the radio device, at least the latter part of said amplified carrier frequency transmission signal comprising distortion;

detecting a signal proportional to said distortion, wherein said proportional signal is detected in the receiver in accordance with said latter part of said amplified carrier frequency transmission signal;

producing a control signal which is proportional to said detected proportional signal; and

applying said control signal to a modulator, wherein the modulation of the transmission signal is linearized.

8. A method as in claim 7 wherein the step of detecting a signal proportional to said distortion comprises the initial step of demodulating the transmission signal.

9. A method as in claim 7 wherein the step of producing a control signal comprises the initial step of providing a signal processing unit with said detected proportional signal, wherein said signal processing unit calculates said control signal.

10. A method as in claim 7 wherein the step of detecting a signal proportional to said distortion comprises the initial step of detecting I and Q components of a quadrature modulated transmission signal.

11. A method as in claim 7 wherein the step of inputting part of an amplified carrier frequency transmission signal of the transmitter to the receiver of the radio device comprises the step of inputting said amplified carrier frequency transmission signal to the carrier frequency portion of the signal path of the receiver.

12. A circuit for regulating the power of a transmission signal of a radio device, comprising:

a radio device having a transmitter and a receiver;

a power divider located in the signal path of said transmitter, wherein the transmission signal from said transmitter is divided into at least two output transmission signals;

means for transmitting one of said output transmission signals from said power divider from the radio device;

a coupling means which electrically communicates one of said output transmission signals from said power divider to the signal path of said receiver;

a first control signal produced within said receiver in accordance with said one of said output transmission signals from said power divider to the signal path of said receiver, wherein said first control signal is proportional to said transmitter output power; and

an adjustable amplifier in the transmitter signal path, said adjustable amplifier is controlled by said first control signal.

13. A circuit as in claim 12 wherein said coupling means comprises a controllable switch, wherein at least one of said output transmission signals of said power divider can be controllably connected and disconnected to said signal path of said receiver.

14. A circuit as in claim 12 wherein said coupling means comprises an attenuator.

15. A circuit as in claim 12 wherein said power divider comprises a directional coupler.

16. A circuit as in claim 12 wherein said power divider comprises a capacitor.

17. A circuit as in claim 12 for regulating power of and linearizing a transmission signal of a radio device, further comprising:

a second control signal produced within said receiver, wherein said second control signal is proportional to the distortion present in the transmission signal of said transmitter;

a modulator controlled by said second control signal, whereby the transmission signal is linearized.

18. A circuit as in claim 17 further comprising a signal processing unit, wherein said signal processing unit produces said first control signal and second control signal and provides said first control signal to said amplifier and said second control signal to said modulator.

19. A circuit as in claim 12 wherein said power regulator is an amplifier.

20. A circuit as in claim 12 wherein said power regulator is an attenuator.

21. A circuit as in claim 12 wherein said radio device is a time-division, TDD, radio telephone system.

22. A circuit as in claim 12 wherein said radio device is a frequency-division, FDD, radio telephone system based on continuous transmission and reception.

23. A circuit as in claim 12 wherein said radio device is a code-division, CDMA, radio telephone system based on continuous transmission and reception.

24. A circuit as in claim 12 wherein said receiver is based on direct conversion.

25. A circuit as in claim 12 further comprising a signal processing unit, wherein said signal processing unit produces said first control signal and second control signal and provides said first control signal to said power regulator and said second control signal to said modulator.

26. A circuit for linearizing a transmission signal of a radio device, comprising:

a radio device having a transmitter and a receiver;

a power divider located in the signal path of said transmitter, wherein the transmission signal is divided into at least two output transmission signals;

means for transmitting one of said output transmission signals from said power divider from the radio device;

a coupling means which electrically communicates one of said output transmission signals of said power divider to the signal path of said receiver;

a control signal produced within said receiver in accordance with said one of said output transmission signals from said power divider to the signal path of said receiver, wherein said control signal is proportional to the distortion present in the transmission signal of said transmitter; and

a modulator controlled by said control signal, whereby the transmission signal is linearized.

27. A circuit as in claim 26 wherein said coupling means comprises a controllable switch, wherein at least one of said output transmission signals of said power divider can be controllably connected and disconnected to said signal path of said receiver.

28. A circuit as in claim 26 wherein said coupling means comprises a attenuator.

29. A circuit as in claim 26 wherein said power divider comprises a directional coupler.

30. A circuit as in claim 26 wherein said power divider comprises a capacitor.