Filtering characteristic adjustments of weakly coupled tunable RF filters

• US 9,774,311 B2
• Filed: 11/26/2014
• Issued: 09/26/2017
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Inventors: Maxim, George, Scott, Baker, Leipold, Dirk Robert Walter
• Primary Examiner(s): Jones, Stephen E
• Assistant Examiner(s): PATEL, RAKESH BHASKARBHAI
• Application Number:
  US14/555,371
• Publication Number:
  US 20150084713A1
• Time in Patent Office: 1,035 Days
• Field of Search: 333 171, 333132, 333175, 333174
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• 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 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 2200/429 Two or more amplifiers or one amplifier with filters for different frequency bands are coupled in parallel at the input or output
• CPC Class Codes: H03F 2200/546 A tunable capacitance being present in an amplifier circuit
• CPC Class Codes: H03F 3/195 in integrated circuits
• 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: H03H 7/0115 comprising only inductors and capacitors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence
• CPC Class Codes: H03H 7/0153 Electrical filters; Controlling thereof
• CPC Class Codes: H03H 7/0161 Bandpass filters H03H7/12 takes precedence
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H03H 7/463 Duplexers

Abstract

RF communications circuitry, which includes a first RF filter structure and RF detection circuitry, is disclosed. The first RF filter structure includes a first group of RF resonators, which include a first pair of weakly coupled RF resonators coupled to a signal path of a first RF signal. One of the first group of RF resonators provides a first sampled RF signal. The RF detection circuitry detects the first sampled RF signal to provide a first detected signal. The first RF filter structure adjusts a first filtering characteristic of the first RF filter structure based on the first detected signal.

Claims

1. An apparatus comprising:

a first RF filter structure comprising a first plurality of RF resonators and configured to adjust a first filtering characteristic of the first RF filter structure based on a first detected signal, wherein;

the first plurality of RF resonators comprises a a first resonator, a second resonator, and a third resonator;

during a first configuration of the first RF filter structure, the first resonator is coupled to the second resonator and the first resonator is not coupled to the third resonator;

during a second configuration of the first RF filter structure, the first resonator is coupled to the second resonator via the third resonator;

one of the first plurality of RF resonators is configured to provide a first sampled RF signal; and

RF detection circuitry configured to detect the first sampled RF signal to provide the first detected signal.

2. The apparatus of claim 1 wherein the first plurality of RF resonators comprises a first pair of weakly coupled RF resonators, which comprises the first resonator and the second resonator, such that each of the first pair of weakly coupled RF resonators comprises a corresponding resonating inductive element to form a first pair of resonating inductive elements, such that a magnetic coupling coefficient between each of the first pair of resonating inductive elements is less than 0.3.

3. The apparatus of claim 1 wherein the first RF filter structure further comprises a unidirectional coupling stage coupled to the first plurality of RF resonators, such that the unidirectional coupling stage is configured to provide amplification in a forward direction.

4. The apparatus of claim 1 wherein the first RF filter structure further comprises a bidirectional coupling stage coupled to the first plurality of RF resonators, such that the bidirectional coupling stage is configured to provide coupling in a forward direction and a reverse direction.

5. The apparatus of claim 1 wherein control circuitry is configured to receive the first detected signal and provide a first filter control signal to the first RF filter structure based on the first detected signal, such that the first RF filter structure is further configured to adjust the first filtering characteristic based on the first filter control signal.

6. The apparatus of claim 5 wherein the control circuitry comprises a resonator frequency tuning block, which is configured to provide the first filter control signal.

7. The apparatus of claim 1 wherein the first RF filter structure is further configured to operate in one of an FDD operating mode, a TDD transmit mode, and a TDD receive mode.

8. The apparatus of claim 1 wherein control circuitry is configured to receive the first detected signal and provide a first filter reconfiguration signal to the first RF filter structure based on the first detected signal, such that the first RF filter structure is further configured to adjust the first filtering characteristic based on the first filter reconfiguration signal.

9. The apparatus of claim 8 wherein the control circuitry comprises a coupling tuning block, which is configured to provide the first filter reconfiguration signal.

10. The apparatus of claim 1 wherein the first filtering characteristic is associated with at least one signal path through the first plurality of RF resonators.

11. The apparatus of claim 1 wherein the first filtering characteristic is associated with a single signal path through at least three of the first plurality of RF resonators.

12. The apparatus of claim 11 wherein the first filtering characteristic provides interference rejection filtering.

13. The apparatus of claim 11 wherein the first detected signal is an indication of an interfering signal.

14. The apparatus of claim 1 wherein the first filtering characteristic is associated with at least two parallel signal paths through the first plurality of RF resonators.

15. The apparatus of claim 14 wherein an insertion loss of the at least two parallel signal paths is less than an insertion loss of any one of the at least two parallel signal paths.

16. The apparatus of claim 1 wherein the first detected signal is an indication of an absence of an interfering signal.

17. The apparatus of claim 1 wherein the first filtering characteristic is associated with a bandpass filter response.

18. The apparatus of claim 1 wherein the first filtering characteristic is associated with a bandpass filter response with at least one notch filter response.

19. The apparatus of claim 1 wherein the first filtering characteristic is associated with an impedance transformation via a path through the first plurality of RF resonators.

20. The apparatus of claim 1 wherein electric coupling between two of the first plurality of RF resonators is configured to be adjusted based on a first filter reconfiguration signal.

21. The apparatus of claim 1 wherein the first plurality of RF resonators has electric coupling and magnetic coupling between the first RF resonator and the second RF resonator.

22. The apparatus of claim 21 wherein the electric coupling is configured to be adjusted to provide one of about a net zero coupling, a net positive coupling, and a net negative coupling between the first RF resonator and the second RF resonator based on a first filter reconfiguration signal.

23. The apparatus of claim 21 wherein the electric coupling and the magnetic coupling are configured to be adjusted to provide one of about a net zero coupling, a net positive coupling, and a net negative coupling between the first RF resonator and the second RF resonator based on a first filter reconfiguration signal.

24. The apparatus of claim 1 wherein the first RF filter structure is further configured to further adjust the first filtering characteristic of the first RF filter structure based on external information.