POWER AND IMPEDANCE MEASUREMENT CIRCUITS FOR A WIRELESS COMMUNICATION DEVICE

• US 20100321086A1
• Filed: 10/16/2009
• Published: 12/23/2010
• Est. Priority Date: 06/19/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Hadjichristos, Aristotele, Sahota, Gurkanwal Singh, Ballantyne, Gary J., See, Puay Hoe, Cicalini, Alberto
• Granted Patent: US 8,963,611 B2
• Time in Patent Office: Days
• US Class Current: 327/359
• CPC Class Codes: G01R 21/01 in circuits having distributed constants G01R21/04, G01R21/07, G01R21/09, G01R21/12 take precedence
• CPC Class Codes: G01R 27/04 in circuits having distributed constants , e.g. having very long conductors or involving high frequencies
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H04B 1/0458 Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H

Abstract

Exemplary embodiments disclosed are directed to power and impedance measurement circuits that may be used to measure power and/or impedance are described. A measurement circuit may include a sensor and a computation unit. The sensor may sense (i) a first voltage signal across a series circuit coupled to a load to obtain a first sensed signal and (ii) a second voltage signal at a designated end of the series circuit to obtain a second sensed signal. The sensor may mix (i) a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output and (ii) a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output. The computation unit may determine the impedance and/or delivered power at the designated end of the series circuit based on the sensor outputs.

Claims

1. An apparatus comprising:

a sensor to sense a first voltage signal across first and second ends of a series circuit coupled to a load to obtain a first sensed signal, to sense a second voltage signal at the second end of the series circuit to obtain a second sensed signal, and to provide a sensor output generated based on the first and second sensed signals; and

a computation unit coupled to the sensor and to determine power delivered to the load based on the sensor output.

2. The apparatus of claim 1, the sensor comprising

an amplifier to receive first and second input signals obtained from the first and second ends, respectively, of the series circuit and provide the first sensed signal, and

a multiplier coupled to the amplifier and to multiply the first sensed signal with a version of the second sensed signal and provide a multiplier output.

3. The apparatus of claim 2, the sensor further comprising

a buffer to receive the second input signal and provide the second sensed signal, and

a phase shifter coupled to the buffer and to provide a phase-shifted version of the second sensed signal to the multiplier.

4. The apparatus of claim 2, the sensor further comprising

a lowpass filter coupled to the multiplier and to filter the multiplier output and provide the sensor output.

5. The apparatus of claim 2, the sensor further comprising

a first programmable attenuator coupled to the first end of the series circuit and to provide the first input signal, and

a second programmable attenuator coupled to the second end of the series circuit and to provide the second input signal.

6. The apparatus of claim 1, the sensor comprising

an amplifier to receive first and second input signals obtained from the first and second ends, respectively, of the series circuit and provide the first sensed signal,

a buffer to receive the second input signal and provide the second sensed signal,

a phase shifter coupled to the buffer and to provide a phase-shifted signal,

a multiplier coupled to the amplifier and the phase shifter and to multiply the first sensed signal with the phase-shifted signal and provide a multiplier output, and

a lowpass filter coupled to the multiplier and to filter the multiplier output and provide the sensor output.

7. The apparatus of claim 1, the computation unit to scale the sensor output based on impedance of the series circuit and provide the power delivered to the load.

8. The apparatus of claim 1, the series circuit comprising an inductor coupled between the first and second ends of the series circuit.

9. The apparatus of claim 1, further comprising:

a tunable matching circuit comprising the series circuit; and

a power amplifier coupled to the tunable matching circuit, the tunable matching circuit being adjusted based on the power delivered to the load

10. A method comprising:

sensing a first voltage signal across first and second ends of a series circuit coupled to a load to obtain a first sensed signal;

sensing a second voltage signal at the second end of the series circuit to obtain a second sensed signal;

generating a sensor output based on the first and second sensed signals; and

determining power delivered to the load based on the sensor output.

11. The method of claim 10, further comprising:

adjusting a matching circuit comprising the series circuit based on the power delivered to the load.

12. An apparatus comprising:

means for sensing a first voltage signal across first and second ends of a series circuit coupled to a load to obtain a first sensed signal;

means for sensing a second voltage signal at the second end of the series circuit to obtain a second sensed signal;

means for generating a sensor output based on the first and second sensed signals; and

means for determining power delivered to the load based on the sensor output.

13. An apparatus comprising:

a sensor to sense a first voltage signal across first and second ends of a series circuit coupled to a load to obtain a first sensed signal, to sense a second voltage signal at the second end of the series circuit to obtain a second sensed signal, to mix a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output, and to mix a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output; and

a computation unit coupled to the sensor and to determine impedance or delivered power at the second end of the series circuit based on the first and second sensor outputs.

14. The apparatus of claim 13, the sensor further to mix a third version of the first sensed signal with the first or second version of the second sensed signal to obtain a third sensor output, and the computation unit to determine the impedance or the delivered power at the second end of the series circuit based further on the third sensor output.

15. The apparatus of claim 13, the second end of the series circuit being coupled to the load, the sensor to sense the second voltage signal at the load, and the computation unit to determine the impedance or delivered power at the load.

16. The apparatus of claim 13, the second end of the series circuit being coupled to a power amplifier, the sensor to sense the second voltage signal at an output of the power amplifier, and the computation unit to determine the impedance or delivered power at the output of the power amplifier.

17. The apparatus of claim 13, the first version of the first sensed signal being the first sensed signal, and the second version of the second sensed signal being the second sensed signal.

18. The apparatus of claim 17, the second version of the first sensed signal being a limited version, or a phase shifted version, or a limited and phase shifted version of the first sensed signal, and the first version of the second sensed signal being a limited version, or a phase shifted version, or a limited and phase shifted version of the second sensed signal.

19. The apparatus of claim 13, the first sensor output being indicative of inphase or quadrature component of the first voltage signal, and the second sensor output being indicative of inphase or quadrature component of the second voltage signal.

20. The apparatus of claim 13, the first sensor output being indicative of phase of the impedance at the second end of the series circuit.

21. The apparatus of claim 13, the sensor comprising

an amplifier to receive first and second input signals obtained from the first and second ends, respectively, of the series circuit and provide the first sensed signal, and

a buffer to receive the second input signal and provide the second sensed signal.

22. The apparatus of claim 21, the sensor further comprising

a first programmable attenuator coupled to the first end of the series circuit and to provide the first input signal, and

a second programmable attenuator coupled to the second end of the series circuit and to provide the second input signal.

23. The apparatus of claim 21, the sensor further comprising

a first switch coupled to the amplifier and to provide one of multiple versions of the first sensed signal comprising the first and second versions of the first sensed signal,

a second switch coupled to the buffer and to provide one of multiple versions of the second sensed signal comprising the first and second versions of the second sensed signal, and

a mixer coupled to the first and second switches and to mix an output signal from the first switch with an output signal from the second switch.

24. The apparatus of claim 23, the sensor further comprising

a lowpass filter coupled to the mixer and to filter a mixer output and provide a sensor output.

25. The apparatus of claim 13, the sensor comprising

a first mixer to mix the first version of the first sensed signal with the first version of the second sensed signal and provide a first mixer output used to generate the first sensor output, and

a second mixer to mix the second version of the first sensed signal with the second version of the second sensed signal and provide a second mixer output used to generate the second sensor output.

26. The apparatus of claim 25, the sensor further comprising

a third mixer to mix a third version of the first sensed signal with a third version of the second sensed signal and provide a third mixer output used to generate a third sensor output, the computation unit to determine the impedance or delivered power at the second end of the series circuit based further on the third sensor output.

27. The apparatus of claim 25, the sensor further comprising

at least one lowpass filter coupled to the first and second mixers and to filter the first and second mixer outputs and provide the first and second sensor outputs.

28. The apparatus of claim 13, further comprising:

a reactive element coupled in series with a switch, the reactive element and the switch being coupled between the second end of the series circuit and circuit ground,

the computation unit to obtain a first measurement of the first and second sensor outputs with the switch closed, to obtain a second measurement of the first and second sensor outputs with the switch opened, and to determine the impedance or delivered power at the second end of the series circuit based on the first and second measurements.

29. The apparatus of claim 13, further comprising:

a reactive element coupled in series with a switch, the reactive element and the switch being coupled between the first and second ends of the series circuit,

the computation unit to obtain a first measurement of the first and second sensor outputs with the switch closed, to obtain a second measurement of the first and second sensor outputs with the switch opened, and to determine the impedance or delivered power at the second end of the series circuit based on the first and second measurements.

30. The apparatus of claim 13, further comprising:

a tunable matching circuit comprising the series circuit; and

a power amplifier coupled to the tunable matching circuit, the tunable matching circuit being adjusted based on the impedance or delivered power at the second end of the series circuit.

31. A wireless device comprising:

a first power amplifier to amplify a first input radio frequency (RF) signal and provide a first amplified RF signal;

a first tunable matching circuit coupled to the first power amplifier and to provide output impedance matching for the first power amplifier, to receive the first amplified RF signal, and to provide a first output RF signal; and

a measurement circuit coupled to the first tunable matching circuit and to measure first impedance or delivered power at output of the first tunable matching circuit, the first tunable matching circuit being adjusted based on the measured first impedance or delivered power.

32. The wireless device of claim 31, further comprising:

a second power amplifier to amplify a second input RF signal and provide a second amplified RF signal; and

a second tunable matching circuit coupled to the second power amplifier and to provide output impedance matching for the second power amplifier, to receive the second amplified RF signal, and to provide a second output RF signal, the measurement circuit further to measure second impedance or delivered power at output of the second tunable matching circuit, the second tunable matching circuit being adjusted based on the measured second impedance or delivered power.

33. The wireless device of claim 32, further comprising:

a third tunable matching circuit coupled to the first and second tunable matching circuits, to receive and combine the first and second amplified RF signals, and to provide a third output RF signal, the measurement circuit further to measure third impedance or delivered power at output of the third tunable matching circuit, the third tunable matching circuit being adjusted based on the measured third impedance or delivered power.

34. A method comprising:

sensing a first voltage signal across first and second ends of a series circuit coupled to a load to obtain a first sensed signal;

sensing a second voltage signal at the second end of the series circuit to obtain a second sensed signal;

mixing a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output;

mixing a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output; and

determining impedance or delivered power at the second end of the series circuit based on the first and second sensor outputs.

35. The method of claim 34, the first version of the first sensed signal being the first sensed signal, the second version of the second sensed signal being the second sensed signal, the second version of the first sensed signal being a limited version, or a phase shifted version, or a limited and phase shifted version of the first sensed signal, and the first version of the second sensed signal being a limited version, or a phase shifted version, or a limited and phase shifted version of the second sensed signal.

36. The method of claim 34, further comprising:

adjusting a tunable matching circuit comprising the series circuit based on the impedance or delivered power at the second end of the series circuit.

37. The method of claim 36, the adjusting the tunable matching circuit comprise

determining a voltage standing wave ratio (VSWR) based on the impedance at the second end of the series circuit, and

adjusting the tunable matching circuit based on the VSWR.

38. An apparatus comprising:

means for sensing a first voltage signal across first and second ends of a series circuit coupled to a load to obtain a first sensed signal;

means for sensing a second voltage signal at the second end of the series circuit to obtain a second sensed signal;

means for mixing a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output;

means for mixing a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output; and

means for determining impedance or delivered power at the second end of the series circuit based on the first and second sensor outputs.

39. A method comprising:

determining impedance of a load;

determining a metric based on the impedance of the load; and

adjusting a matching circuit based on the metric.

40. The method of claim 39, the determining the impedance of the load comprising

sensing a first voltage signal across first and second ends of a series circuit coupled to the load to obtain a first sensed signal,

sensing a second voltage signal at the second end of the series circuit to obtain a second sensed signal,

mixing a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output,

mixing a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output, and

determining the impedance of the load based on the first and second sensor outputs.

41. The method of claim 39, the determining the metric comprising

determining a reflection coefficient based on the impedance of the load, and

determining the metric based on the reflection coefficient.

42. The method of claim 39, the determining the metric comprising

determining a reflection coefficient based on the impedance of the load, and

determining a voltage standing wave ratio (VSWR) based on the reflection coefficient, the metric comprising the VSWR.

43. The method of claim 39, the determining the metric comprising

determining a reflection coefficient based on the impedance of the load, and

determining a mismatch loss based on the reflection coefficient, the metric comprising the mismatch loss.

44. The method of claim 39, the adjusting the matching circuit comprising

adjusting the matching circuit if the metric exceeds a threshold, and

skipping adjustment of the matching circuit if the metric does not exceed the threshold.