Signal-tracking RF bandstop filter

Patent metadata

Field	Value
Publication number	US-10270480-B1
Application number	US-201715726579-A
Country	US
Kind code	B1
Filing date	Oct 6, 2017
Priority date	Oct 6, 2017
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

Systems and methods are provided for implementing bandstop filters (e.g., RF/microwave bandstop filters) that can automatically tune to a frequency of an interfering signal. Embodiments of the present disclosure provide automatically tunable signal-tracking bandstop filters with a significant reduction in response time, complexity, size, weight, and cost when compared to conventional devices.

First claim

What is claimed is:

1. A bandstop filter, comprising:
a first resonator, coupled to a first detector;
a second resonator, coupled to the first resonator, wherein the second resonator is coupled to a second detector; and
a control circuit, coupled to the first detector and the second detector, configured to tune the first resonator and the second resonator in response to detecting a first change in a first voltage at the first detector or a second change in a second voltage at the second detector.

2. The bandstop filter of claim 1 , wherein the first resonator is weakly coupled to the first detector, and wherein the second resonator is weakly coupled to the second detector.

3. The bandstop filter of claim 1 , wherein the first resonator is coupled to the second resonator in a Bridged-T filter topology.

4. The bandstop filter of claim 1 , wherein the first detector is a first detector diode, and wherein the second detector is a second detector diode.

5. The bandstop filter of claim 1 , wherein the control circuit comprises:
a comparator, coupled to the first detector and the second detector;
an integrator, coupled to an output of the comparator; and
a tuner, coupled to an output of the integrator, wherein the tuner is configured to tune the first resonator and the second resonator.

6. The bandstop filter of claim 1 , wherein the first detector and the second detector are configured such that the first voltage is equal to the second voltage when a frequency of an interfering signal is equal to a desired bandstop center frequency of the bandstop filter.

7. The bandstop filter of claim 1 , wherein the control circuit is configured to tune the first resonator and the second resonator to minimize a difference between the first voltage and the second voltage.

8. The bandstop filter of claim 1 , further comprising a third resonator coupled to the first resonator and the second resonator.

9. The bandstop filter of claim 8 , further comprising a third detector weakly coupled to the third resonator.

10. The bandstop filter of claim 1 , wherein a first susceptance value of the first resonator and a second susceptance value of the second resonator are selected based on a desired bandwidth of the bandstop filter.

11. The bandstop filter of claim 1 , wherein a first susceptance value of the first resonator and a second susceptance value of the second resonator are selected based on a desired attenuation of the bandstop filter.

12. The bandstop filter of claim 1 , wherein a first susceptance value of the first resonator and a second susceptance value of the second resonator are selected based on a desired frequency range of the bandstop filter.

13. The bandstop filter of claim 1 , wherein a first susceptance value of the first resonator is selected based on a coupling strength between the first resonator and the first detector.

14. The bandstop filter of claim 1 , wherein a first susceptance value of the first resonator is selected based on a power sensitivity of the first detector.

15. The bandstop filter of claim 1 , wherein a first susceptance value of the first resonator is selected based on a coupling strength between the first resonator and the second resonator.

16. A bandstop filter, comprising:
a first resonator, coupled to a first detector; and
a second resonator, coupled to a second detector, wherein the first detector and the second detector are configured such that a first voltage at the first detector is equal to a second voltage at the second detector when a frequency of an interfering signal is equal to a desired bandstop center frequency of the bandstop filter.

17. The bandstop filter of claim 16 , wherein the first detector and the second detector are coupled to a tuning circuit, and wherein the tuning circuit is coupled to the first resonator and the second resonator.

18. The bandstop filter of claim 17 , wherein the tuning circuit is configured to tune the first resonator and the second resonator in response to detecting a first change in the first voltage or a second change in the second voltage.

19. A bandstop filter, comprising:
a first resonator, weakly coupled to a first detector diode;
a second resonator, coupled to the first resonator, wherein the second resonator is weakly coupled to a second detector diode;
a comparator, coupled to the first detector diode and the second detector diode;
an integrator, coupled to an output of the comparator; and
a tuner, coupled to an output of the integrator, wherein the tuner is configured to tune the first resonator and the second resonator.

20. The bandstop filter of claim 19 , wherein the tuner is configured to tune the first resonator and the second resonator in response to detecting a first change in a first voltage at the first detector diode or a second change in a second voltage at the second detector diode.

Assignees

• Us Navy

Inventors

• Guyette Andrew C
• Naglich Eric J

Classifications

• H03H7/12

  Bandpass or bandstop filters with adjustable bandwidth and fixed centre frequency (H03H7/09 takes precedence) · CPC title

• H04B1/1036 Primary

  with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters (H04B1/123 takes precedence; filter circuits H03H) · CPC title

• H03H7/1741

  Comprising typical LC combinations, irrespective of presence and location of additional resistors (when resistors are present, also classify in H03H7/06 - H03H7/07) · CPC title

• H03H7/0153

  Electrical filters; Controlling thereof · CPC title

• H03J3/06

  Arrangements for obtaining constant bandwidth or gain throughout tuning range or ranges · CPC title