TECHNIQUES FOR IMPROVED ADAPTIVE IMPEDANCE MATCHING

• US 20110014886A1
• Filed: 09/21/2010
• Published: 01/20/2011
• 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: MANSSEN, KEITH R., SMITH, WAYNE E., BLIN, GUILLAUME, GREENE, MATTHEW R.
• Granted Patent: US 8,620,236 B2
• Time in Patent Office: Days
• 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 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 to a change in impedance of a variable load impedance, and wherein said tuning is limited by a subset of a total tuning range, wherein the subset of the total range limits an undesirable effect caused by a transmitted signal.

2. The apparatus of claim 1, wherein the undesirable effect corresponds to a violation in whole or in part of a specification for transmitting RF signals, and wherein tuning is initiated between transmit bursts or during a transmit burst.

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

4. The apparatus of claim 3, 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.

5. An apparatus, comprising:

an RF matching network comprising one or more variable reactive elements; and

wherein said RF matching network is tuned to adapt to a change in impedance of a variable load, and wherein said tuning is limited by a magnitude of each tuning step initiated during a transmit burst in order to at least reduce an undesirable effect caused by a transmitted signal.

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 a variable load; and

wherein said RF matching network is tuned to adapt to a change in impedance of the variable load, and wherein said tuning is limited by avoiding matching to one or more impedances of the variable load to at least reduce an undesirable effect caused by a transmitted RF signal.

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 any predetermined power step.

10. An apparatus, comprising:

an RF matching network coupled 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, and wherein the RF matching network is tuned for a given band, channel or combination thereof to maintain signal integrity of a transmit signal.

11. The apparatus of claim 10, wherein said memory is adapted to recall an initial operating impedance for said RF matching network, and wherein said initial operating impedance is used as a starting point for an algorithm to control operations of said RF matching network.

12. The apparatus of claim 10, wherein said RF matching 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.

13. A method, comprising 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.

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 limited tuning is accomplished according to a limited number of impedance tuning steps initiated while radiating the RF signal, a limited change in impedance between tuning steps initiated while radiating the RF signal, or a combination thereof.

16. A non-transitory machine-readable storage medium, comprising computer instructions to limit tuning of a variable reactance network coupled to a variable load impedance to at least reduce an undesirable effect caused by an RF signal.

17. The non-transitory machine-readable storage medium of claim 16, wherein said limited tuning is accomplished according to a limited number of impedance tuning steps initiated while radiating the RF signal, a limited change in magnitude of impedance values between tuning steps initiated while radiating the RF signal, or a combination thereof.

18. The non-transitory machine-readable storage medium 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 impedance to avoid one or more matching impedances of the antenna to at least reduce an undesirable effect caused by a transmitted RF signal.

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

21. An apparatus, comprising:

a variable reactance network coupled to a variable load impedance; and

wherein said variable reactance network is tuned to adapt to a change in impedance of the variable load impedance, wherein said tuning of the variable reactance network is limited, and wherein said tuning occurs between transmit bursts to at least reduce an undesirable effect caused by transmitted signals during the transmit bursts.

22. The apparatus medium of claim 21, 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.

23. The apparatus 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.

24. The apparatus medium of claim 21, wherein said variable reactance network is tuned according to at least one of:

a limited number of tuning steps;

limiting a magnitude of a change in impedance between tuning steps; and

avoiding one or more tuning impedances of the variable reactive network.