Techniques for improved adaptive impedance matching

• US 7,917,104 B2
• Filed: 04/23/2007
• Issued: 03/29/2011
• Est. Priority Date: 04/23/2007
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Paratek Microwave Incorporated (Blackberry Limited)
• Inventors: Smith, Wayne E., Blin, Guillaume, Manssen, Keith R., Greene, Matthew R.
• Primary Examiner(s): Nguyen; Duc M
• Application Number:
  US11/789,015
• Publication Number:
  US 20080261544A1
• Time in Patent Office: 1,436 Days
• Field of Search: 455/67.11, 455/115.1, 455/115.4, 455/120, 455/121, 455/125, 455/126, 4551931-1933
• 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 an apparatus, comprising an RF matching network connected to at least one RF input port and at least one RF output port and including one or more voltage or current controlled variable reactive elements; and wherein the RF matching network is tuned to optimize the RF matching network and wherein said tuning is limited by a predetermined number of tuning steps that are taken within a transmit burst and/or limited by the magnitude of each step taken within a transmit burst and/or limited to the steps only being allowed between bursts.

Claims

1. An apparatus, comprising:

an RF matching network coupled to at least one RF input port and at least one RF output port and including one or more voltage or current controlled variable reactive elements; and

wherein said RF matching network is tuned to adapt said RF matching network to a change in impedance of a variable load impedance, and wherein said tuning is limited by a predetermined number of tuning steps that are taken within a transmit burst, wherein the predetermined number of tuning steps limit an undesirable effect on a transmitted signal in the transmit burst when the RF matching network is tuned according to an unconstrained number of tuning steps.

2. The apparatus of claim 1, wherein said tuning steps taken within transmit bursts are accomplished by using time delays corresponding to said transmission bursts.

3. The apparatus of claim 1, wherein said tuning is accomplished by varying the voltage or current to said voltage or current controlled variable reactive elements.

4. The apparatus of claim 3, wherein said variable reactive elements correspond to at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, and variable dielectric capacitors.

5. An apparatus, comprising:

an RF matching network coupled to at least one RF input port and at least one RF output port and including one or more voltage or current controlled variable reactive elements; and

wherein said RF matching network is tuned to adapt said RF matching network to a change in impedance of a variable load impedance, and wherein said tuning is limited by a magnitude of each tuning step taken within a transmit burst, wherein limiting the magnitude of each tuning step limits an undesirable effect on a transmitted signal in the transmit burst when the RF matching network is tuned according to an unconstrained magnitude of each tuning step.

6. The apparatus of claim 5, wherein a portion of said tuning steps takes place between transmission bursts while the transmitter is inactive.

7. The apparatus of claim 5, wherein said variable reactive elements correspond to at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, and variable dielectric capacitors.

8. An apparatus, comprising:

an RF matching network coupled to at least one RF input port and at least one RF output port and including one or more variable reactive elements; and

wherein said RF matching network is tuned to adapt said RF matching network to a change in impedance of a variable load impedance, wherein said tuning is limited by avoiding certain matching impedances of the variable load impedance, and wherein said avoidance of certain matching impedances limits an undesirable effect on a transmitted RF signal when the RF matching network is tuned to one of the avoided matching impedances.

9. The apparatus of claim 8, wherein said tuning is adapted to be placed in a default position when said apparatus is a cellular handset transmitter operating at full power or any predetermined power step.

10. An apparatus, comprising:

an RF matching network coupled to at least one RF input port and at least one RF output port and including one or more variable reactive elements;

wherein said RF matching network is tuned to adapt said RF matching network to a variable load impedance; and

wherein a plurality of tunable impedance values of the RF matching network are stored in a memory, wherein said memory is indexed according to at least one of a frequency band or a group of communication channels for tuning the RF matching network, wherein said tuning of the RF matching network for a given band or channel occurs during a transmit burst, and wherein said tuning is controlled in a manner that maintains signal integrity of a transmit signal in the transmit burst.

11. The apparatus of claim 10, wherein said memory is adapted to recall an initial operating impedance for said RF matching network.

12. The apparatus of claim 11, wherein said initial operating impedance is used as a starting point for an algorithm to control operations of said RF matching network.

13. A method, comprising tuning a matching network having variable reactive elements coupled to an antenna having a variable load impedance according to a subset of a total tuning range of the matching network while radiating an RF signal from said antenna, wherein the subset of the total tuning range of the matching network limits an undesirable effect on the RF signal when the matching network is tuned according to the total tuning range.

14. The method of claim 13, comprising using time delays for tuning said matching network while radiating said RF signal.

15. The method of claim 13, wherein said tuning is accomplished by varying a voltage or current applied to said variable reactive elements, and wherein the subset of the total tuning range corresponds to at least one of a limited number of impedance tuning steps of the matching network or a limited change in magnitude of impedance values between tuning steps.

16. A method, comprising adapting an impedance of a variable reactance network coupled to an antenna having a variable load impedance according to a subset of a total tuning range of the variable reactance network while transmitting an RF signal through the antenna, wherein the subset of the total tuning range limits an undesirable effect on the RF signal when the matching network is tuned according to the total tuning range.

17. The method of claim 16, wherein the subset of the total tuning range corresponds to at least one of a limited number of impedance tuning steps of the variable reactance network or a limited change in magnitude of impedance values between tuning steps.

18. The method of claim 16, wherein said variable reactive network comprises at least one of semiconductor varactors, micro-electro-mechanical systems (MEMS) varactors, MEMS switched reactance components, semiconductor switched reactance components, and variable dielectric capacitors.

19. A non-transitory machine-readable storage medium, comprising computer instructions to tune a variable reactance matching network coupled to a variable load antenna while avoiding one or more matching impedances of the antenna to limit an undesirable effect on a transmitted RF signal when the variable reactance matching network is tuned to one of the avoided matching impedances.

20. The storage medium of claim 19, comprising computer instructions to tune the variable reactance matching network while transmitting an RF signal through the antenna.

21. A non-transitory machine-readable storage medium, comprising computer instructions to tune a variable reactance network coupled to a variable load antenna according to a subset of a total tuning range of the variable reactance network while transmitting an RF signal through the antenna, wherein the subset of the total tuning range limits an undesirable effect on the RF signal when the variable reactance network is tuned according to the total tuning range.

22. The storage medium of claim 21, comprising computer instructions to:

recall one or more operating states of a mobile communication device from which the variable reactance network operates; and

adapt an impedance of the variable reactance network according to the recalled one or more operating states.

23. The storage medium of claim 22, wherein said operating states correspond to a mechanical state of a housing assembly of the mobile communication device.

24. The storage medium of claim 21, wherein the subset of the total tuning range corresponds to at least one of a limited number of impedance tuning steps of the variable reactance network or a limited change in magnitude of impedance values between tuning steps.

25. An apparatus, comprising:

a variable reactance network coupled to at least one RF input port and at least one RF output port and including one or more controllable variable reactive elements; and

wherein said variable reactance network is tuned to adapt said variable reactance network to a change in impedance of a variable load impedance, and wherein said tuning is limited by a magnitude of each tuning step that is taken between transmit bursts to limit an undesirable effect on transmitted signals during the transmit bursts caused by tuning the variable reactance network according to an unconstrained magnitude of each tuning step.