VSWR DETECTOR FOR A TUNABLE FILTER STRUCTURE

• US 20150038094A1
• Filed: 08/01/2014
• Published: 02/05/2015
• Est. Priority Date: 08/01/2013
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Maxim, George, Leipold, Dirk Robert Walter, Scott, Baker
• Granted Patent: US 9,755,671 B2
• Time in Patent Office: Days
• US Class Current: 455/77
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 2200/267 A capacitor based passive circuit, e.g. filter, being used in an amplifying circuit
• CPC Class Codes: H03F 2200/391 the output circuit of an amplifying stage comprising an LC-network
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2203/7209 the gated amplifier being switched from a first band to a second band
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03H 2210/012 Centre frequency; Cut-off frequency
• CPC Class Codes: H03H 2210/025 Capacitor
• CPC Class Codes: H03H 2210/04 Filter calibration method
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H03H 7/1775 Parallel LC in shunt or branch path H03H7/1791 takes precedence
• 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

Embodiments of radio frequency (RF) filter front-end circuitry are disclosed that include a tunable RF filter structure having weakly coupled resonators and a Voltage Standing Wave Ratio (VSWR) control circuit. The VSWR control circuit is configured to detect a VSWR at a terminal of the tunable RF filter structure and to dynamically tune the tunable RF filter structure based on the VSWR. In this manner, the VSWR control circuit tunes the tunable RF filter structure to improve performance of tunable RF filter structure over variations in the VSWR.

Claims

1. Radio frequency (RF) front-end circuitry comprising:

a tunable RF filter structure comprising a pair of weakly coupled resonators; and

a Voltage Standing Wave Ratio (VSWR) control circuit configured to;

detect a VSWR of the tunable RF filter structure; and

dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure.

2. The RF front-end circuitry of claim 1 wherein the tunable RF filter structure comprises a plurality of tunable RF filter paths and wherein the VSWR control circuit is configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure by being configured to dynamically tune the tunable RF filter structure so as to reduce parasitic coupling between any combination of the tunable RF filter paths.

3. The RF front-end circuitry of claim 1 wherein the tunable RF filter structure comprises a first plurality of terminals connected to RF circuitry and a second plurality of terminals connected to one or more antennas, wherein the VSWR control circuit is configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure by being configured to dynamically tune the tunable RF filter structure so as to match an impedance at any of the first plurality of terminals and an impedance at any of the second plurality of terminals.

4. The RF front-end circuitry of claim 3 wherein the RF circuitry comprises RF receive circuitry connected to a first one of the first plurality of terminals.

5. The RF front-end circuitry of claim 4 wherein the RF receive circuitry is connected to a second one of the first plurality of terminals.

6. The RF front-end circuitry of claim 4 wherein the RF circuitry further comprises RF transmit circuitry connected to a second one of the first plurality of terminals.

7. The RF front-end circuitry of claim 4 wherein the RF receive circuitry comprises a low-noise amplifier.

8. The RF front-end circuitry of claim 3 wherein the RF circuitry further comprises RF transmit circuitry connected to a first one of the first plurality of terminals.

9. The RF front-end circuitry of claim 8 wherein the RF circuitry further comprises RF transmit circuitry connected to a second one of the first plurality of terminals.

10. The RF front-end circuitry of claim 8 wherein the RF transmit circuitry comprises a power amplifier.

11. The RF front-end circuitry of claim 1 wherein the tunable RF filter structure comprises a first tunable RF filter path connected that includes the pair of weakly coupled resonators.

12. The RF front-end circuitry of claim 1 wherein the VSWR control circuit is configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure by being configured to dynamically tune the tunable RF filter structure such that an impedance of the tunable RF filter structure matches an external impedance.

13. The RF front-end circuitry of claim 12 wherein the external impedance is an impedance of an antenna.

14. The RF front-end circuitry of claim 1 wherein the VSWR control circuit only measures the VSWR.

15. The RF front-end circuitry of claim 1 wherein the VSWR control circuit is also configured to control a low-noise amplifier external to the tunable RF filter structure.

16. The RF front-end circuitry of claim 1 wherein the VSWR control circuit comprises:

a VSWR detection circuit operably associated with the tunable RF filter structure and configured to detect the VSWR of the tunable RF filter structure;

an impedance control network configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure.

17. The RF front-end circuitry of claim 16 wherein the VSWR detection circuit comprises a magnitude ratio detector configured to detect a magnitude of the VSWR.

18. The RF front-end circuitry of claim 17 wherein the VSWR detection circuit comprises a phase detector configured to detect a phase of the VSWR.

19. The RF front-end circuitry of claim 16 wherein the VSWR detection circuit is a single-ended VSWR detection circuit.

20. The RF front-end circuitry of claim 16 wherein the VSWR detection circuit is a differential VSWR detection circuit.

21. The RF front-end circuitry of claim 16 wherein the tunable RF filter structure has an input terminal and an output terminal.

22. The RF front-end circuitry of claim 21 wherein the VSWR detection circuit is connected to the input terminal to detect the VSWR.

23. The RF front-end circuitry of claim 21 wherein at least one coupling component connected between the input terminal and a first one of the pair of weakly coupled resonators wherein the impedance control network is configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure impedance control network by being configured to adjust an impedance of the at least one coupling component.

24. The RF front-end circuitry of claim 21 wherein the VSWR detection circuit is connected to the output terminal to detect the VSWR.

25. The RF front-end circuitry of claim 21 wherein at least one coupling component connected between the output terminal and a first one of the pair of weakly coupled resonators wherein the impedance control network is configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure impedance control network by being configured to adjust an impedance of the at least one coupling component.

26. The RF front-end circuit of claim 1 wherein the tunable RF filter structure further comprises a cross coupling capacitor connected between the pair of weakly coupled resonators and wherein an impedance control network is configured to dynamically tune the tunable RF filter structure based on the VSWR of the tunable RF filter structure impedance control network by being configured to adjust a variable capacitance of the cross coupling capacitor.

27. The RF front-end circuitry of claim 1 wherein the VSWR control circuit is also configured to control a power amplifier external to the tunable RF filter structure based on the VSWR.

28. The RF front-end circuitry of claim 1 wherein the tunable RF filter structure comprises multiple RF filter paths and wherein the VSWR control circuit is configured to control the multiple RF filter paths cooperatively based on the VSWR.

29. The RF front-end circuitry of claim 1 wherein the tunable RF filter structure comprises a plurality of resonators that include the pair of weakly coupled resonators and wherein:

a first group of the plurality of resonators are tuned to provide filtering within one or more bands;

the VSWR control circuit is configured to tune a second group of the plurality of resonators based on the VSWR to provide antenna tuning for an antenna.

30. A method, comprising:

detecting a VSWR of a tunable RF filter structure comprising a pair of weakly coupled resonators; and

tuning the tunable RF filter structure dynamically based on the VSWR of the tunable RF filter structure.