Techniques for improved adaptive impedance matching

• US 8,620,236 B2
• Filed: 09/21/2010
• Issued: 12/31/2013
• Est. Priority Date: 04/23/2007
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Blackberry Limited
• Inventors: Manssen, Keith R., Greene, Matthew R., Smith, Wayne E., Blin, Guillaume
• Primary Examiner(s): Nguyen, Duc M
• Application Number:
  US12/887,467
• Publication Number:
  US 20110014886A1
• Time in Patent Office: 1,197 Days
• Field of Search: 455/115.1, 455/121, 455/123, 455/125, 455/126
• US Class Current: 455/121
• CPC Class Codes: H01Q 1/242 specially adapted for hand-held use
• 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: H03H 2007/386 Multiple band impedance matching
• 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

An embodiment of the present invention provides a method for limiting tuning of a matching network having variable reactive elements coupled to a variable load impedance to at least reduce an undesirable effect caused by an RF signal. Other embodiments are disclosed.

Claims

1. An apparatus, comprising:

an RF matching network comprising one or more variable reactive elements,

wherein the RF matching network is tuned to adapt to a change in impedance of a variable load, wherein the tuning for each tuning step is limited within a range up to a pre-determined magnitude for each tuning step initiated during a transmit burst to reduce an undesirable effect that would result in a failure to comply with a transmission specification and that would have occurred based on a transmitted signal if an unconstrained magnitude for each of the tuning steps had been utilized, wherein the transmission specification provides signal specifications for transmission of RF signals in a communication system, and wherein the tuning is initiated from an initial tuning state of the one or more variable reactive elements where the initial tuning state is selected based on a use case of a communication device housing the RF matching network.

2. The apparatus of claim 1, wherein a portion of the tuning takes place between transmission bursts while the transmitter is inactive,

3. The apparatus of claim 1, wherein the transmission specification is promulgated by an entity and includes allowable phase shifts within the transmit burst, and wherein each tuning step is limited by the allowable phase shifts.

4. The apparatus of claim 1, comprising a controller that detects the impedance change of the variable load impedance.

5. The apparatus of claim 4, comprising a controller that utilizes time delays for tuning the matching network while radiating an RF signal.

6. The apparatus of claim 5, wherein the tuning is limited to a pre-determined number of the tuning steps.

7. The apparatus of claim 1, wherein the one or more variable reactive elements comprise a semiconductor varactor.

8. The apparatus of claim 1, wherein the one or more variable reactive elements comprise a micro-electromechanical systems varactor.

9. The apparatus of claim 1, wherein the one or more variable reactive elements comprise a micro-electromechanical systems switched reactance component.

10. The apparatus of claim 1, wherein the one or more variable reactive elements comprise a semiconductor switched reactance component.

11. The apparatus of claim 1, wherein the one or more variable reactive elements comprise a variable dielectric capacitor.

12. The apparatus of claim 5, wherein the tuning utilizes variable increments.

13. An apparatus comprising:

an RE matching network including one or more variable reactive elements,

wherein the RE matching network is tuned to adapt to a change in impedance of a variable load impedance, wherein the tuning is limited to a predetermined number of tuning steps that are taken during a transmit burst to limit an undesirable effect that would result in a failure to comply with a transmission specification and that would have occurred based on a transmitted signal if an unconstrained number of tuning steps had been utilized, wherein the transmission specification provides signal specifications for transmission of RE signals in a communication system, wherein the tuning utilizes variable increments, wherein the tuning is accomplished by varying a voltage or current applied to the one or more variable reactive elements, wherein the tuning is initiated from an initial tuning state of the one or more variable reactive elements where the initial tuning state is selected based on a use case of a communication device housing the RF matching network, and wherein the one or more variable reactive elements comprise at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, variable dielectric capacitors, or combinations thereof.

14. The apparatus of claim 13, wherein the transmission specification is promulgated by an entity and includes allowable phase shifts within the transmit burst, wherein each tuning step is limited by the allowable phase shifts.

15. The apparatus of claim 13,

wherein the tuning is limited by avoiding a matching impedance corresponding to a specific absorption rate threshold.

16. The apparatus of claim 13, wherein the tuning is adapted to be placed in a default position when the apparatus is a cellular handset transmitter operating at any predetermined power step.

17. The apparatus of claim 13, further comprising a memory that is adapted to provide an initial operating impedance for the RF matching network, wherein the initial operating impedance is used as a starting point for an algorithm to control operations of the RF matching network.

18. The apparatus of claim 13, wherein the RF matching network comprises at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, or variable dielectric capacitors.

19. A non-transitory machine-readable storage medium, comprising computer instructions which, responsive to being executed by a processor, cause the processor to perform operations comprising:

detecting an impedance change of a variable load impedance; and

tuning a variable reactance network coupled to the variable load impedance by utilizing at least one of a predetermined number of tuning steps or magnitude-limited tuning steps that are limited within a range up to a predetermined magnitude for each of the tuning steps, wherein the utilization of the at least one of the predetermined number of tuning steps or the magnitude-limited tuning steps reduces an undesirable effect that would result in a failure to comply with a transmission specification and that would have occurred based on an RF signal if an unconstrained magnitude for each of the tuning steps or an unconstrained number of tuning steps had been utilized, wherein the transmission specification provides signal specifications for transmission of RF signals in a communication system, wherein the tuning is initiated from an initial tuning state of one or more variable reactive elements of the RF matching network where the initial tuning state is selected based on a use case of a communication device housing the RF matching network.

20. The non-transitory machine-readable storage medium of claim 19, wherein the tuning utilizes variable increments.

21. The non-transitory machine-readable storage medium of claim 19, wherein the variable reactance network comprises at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, or variable dielectric capacitors.

22. The non-transitory machine-readable storage medium of claim 19, wherein the variable reactance network comprises a semiconductor varactor.

23. The non-transitory machine-readable storage medium of claim 19, wherein the variable reactance network comprises a micro-electro-mechanical systems varactor.

24. The non-transitory machine-readable storage medium of claim 19, wherein the variable reactance network comprises a micro-electro-mechanical systems switched reactance component.

25. The non-transitory machine-readable storage medium of claim 19, wherein the variable reactance network comprises a semiconductor switched reactance component.

26. The non-transitory machine-readable storage medium of claim 19, wherein the variable reactance network comprises a variable dielectric capacitor.

27. A method comprising:

detecting, by a processor, an impedance change of a variable load impedance; and

tuning, by the processor, a variable reactance network coupled to the variable load impedance by utilizing at least one of a predetermined number of tuning steps or magnitude-limited tuning steps that are limited within a range up to a predetermined magnitude for each of the tuning steps, wherein the utilization of the at least one of the predetermined number of tuning steps or the magnitude-limited tuning steps reduces an undesirable effect that would result in a failure to comply with a transmission specification and that would have occurred based on an RF signal if an unconstrained magnitude for each of the tuning steps or an unconstrained number of tuning steps had been utilized, wherein the transmission specification provides signal specifications for transmission of RF signals in a communication system, wherein the tuning is initiated from an initial tuning state of one or more variable reactive elements of the RF matching network where the initial tuning state is selected based on a use case of a communication device housing the RF matching network.

28. A method comprising:

detecting, by a processor, an impedance change of a variable load impedance; and

tuning, by the processor, an RF matching network to adapt to the impedance change, wherein the tuning for each tuning step is limited within a range up to a pre-determined magnitude for each tuning step initiated during a transmit burst to reduce an undesirable effect that would result in a failure to comply with a transmission specification and that would have occurred based on a transmitted signal if an unconstrained magnitude for each of the tuning steps had been utilized, wherein the transmission specification provides signal specifications for transmission of RF signals in a communication system, and wherein the tuning is initiated from an initial tuning state of one or more variable reactive elements of the RF matching network where the initial tuning state is selected based on a use case of a communication device housing the RF matching network.

29. A method comprising:

detecting, by a processor, an impedance change of a variable load impedance; and

tuning, by the processor, an RF matching network to adapt to the impedance change, wherein the tuning is limited to a predetermined number of tuning steps that are taken during a transmit burst to limit an undesirable effect that would result in a failure to comply with a transmission specification and that would have occurred based on a transmitted signal if an unconstrained number of tuning steps had been utilized, wherein the transmission specification provides signal specifications for transmission of RF signals in a communication system, wherein the tuning utilizes variable increments, wherein the tuning is accomplished by varying a voltage or current applied to one or more variable reactive elements of the RF matching network, wherein the tuning is initiated from an initial tuning state of the one or more variable reactive elements where the initial tuning state is selected based on a use case of a communication device housing the RF matching network, and wherein the one or more variable reactive elements comprise at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, variable dielectric capacitors, or combinations thereof.