Network synthesis design of microwave acoustic wave filters

Patent metadata

Field	Value
Publication number	US-9934345-B2
Application number	US-201715673916-A
Country	US
Kind code	B2
Filing date	Aug 10, 2017
Priority date	Mar 15, 2013
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A method of designing an acoustic microwave filter in accordance with frequency response requirements. The method comprises selecting an initial filter circuit structure including a plurality of circuit elements comprising at least one resonant element and at least one other reactive circuit element, selecting circuit response variables based on the frequency response requirements, selecting a value for each of the circuit elements based on the selected circuit response variables to create an initial filter circuit design, transforming the resonant element(s) and the other reactive circuit element(s) of the initial filter circuit design into at least one acoustic resonator model to create an acoustic filter circuit design, adding parasitic effects to the acoustic filter circuit design to create a pre-optimized filter circuit design, optimizing the pre-optimized filter circuit design to create a final filter circuit design, and constructing the acoustic microwave filter based on the final filter circuit design.

First claim

What is claimed is:

1. A method of designing an acoustic microwave filter in accordance with frequency response requirements, comprising:
(a) selecting an initial filter circuit structure including a plurality of circuit elements comprising at least one resonant element and at least one other reactive circuit element;
(b) selecting circuit response variables based on the frequency response requirements;
(c) selecting a value for each of the circuit elements based on the selected circuit response variables to create an initial filter circuit design;
(d) transforming the at least one resonant element and the at least one other reactive circuit element of the initial filter circuit design into at least one acoustic resonator model to create an acoustic filter circuit design;
(e) creating different versions of the acoustic filter circuit design;
(f) computing one or more performance parameters for each of the different acoustic filter design versions;
(g) comparing the one or more computed performance parameters for the different acoustic filter design versions to each other;
(h) selecting one of the different acoustic filter circuit designs based on the comparison;
(i) optimizing the selected acoustic filter circuit design version to create a final filter circuit design; and
(j) constructing the acoustic microwave filter based on the final filter circuit design.

2. The method of claim 1 , wherein creating different versions of the acoustic filter circuit design comprises changing the order in which the plurality of resonant elements in the acoustic filter circuit design are disposed along a signal transmission path.

3. The method of claim 1 , wherein creating different versions of the acoustic filter circuit design comprises selecting different values for at least one of the circuit elements.

4. The method of claim 1 , wherein the one or more performance parameters comprises one or more of an insertion loss, return loss, rejection, group delay, node voltages, and branch currents.

5. The method of claim 1 , wherein the frequency requirements comprise one or more of a frequency dependent return loss, insertion loss, rejection, and linearity.

6. The method of claim 1 , wherein the frequency response requirements comprise a passband in 500-3500 MHz range.

7. The method of claim 1 , wherein the frequency response requirements comprise a passband and a stopband.

8. The method of claim 1 , wherein each of the at least one resonator comprises a parallel L-C resonator combination of a capacitor and an inductor.

9. The method of claim 1 , wherein the at least one other reactive circuit element comprises a capacitor.

10. The method of claim 1 , wherein the initial filter circuit structure is an in-line non-resonant-node circuit structure.

11. The method of claim 1 , wherein the circuit response variables are in the form of a ratio between numerator polynomials defining transmission zeroes and denominator polynomials defining reflection zeroes multiplied by a scale factor.

12. The method of claim 11 , wherein the total number of transmission zeroes are equal to or greater than the total number of reflection zeroes.

13. The method of claim 1 , wherein each of the at least one acoustic resonator model is a Butterworth-Van Dyke (BVD) model.

14. The method of claim 13 , wherein the at least one resonator comprises an in-shunt parallel L-C resonator combination, the at least one other reactive circuit element comprises an in-shunt admittance inverter in series with the in-shunt parallel L-C-resonator combination, and an in-shunt non-resonant susceptance in parallel with the in-shunt parallel L-C resonator combination, and wherein the in-shunt parallel L-C resonator combination, in-shunt admittance inverter, and in-shunt non-resonant susceptance are transformed into one of the at least one BVD model.

15. The method of claim 14 , wherein the in-shunt parallel L-C resonator combination and the in-shunt admittance inverter are transformed into an in-shunt series L-C resonator combination, and the in-shunt series L-C resonator combination and in-shunt non-resonant susceptance are transformed into the one BVD model.

16. The method of claim 14 , wherein the BVD model is an in-shunt BVD model.

17. The method of claim 16 , wherein the at least one reactive circuit element further comprises two in-line admittance inverters coupled to a node between the in-shunt parallel L-C resonator combination and the in-shunt non-resonant susceptance, and wherein the in-shunt BVD model and the two in-line admittance inverters are transformed into an in-line BVD model and a reactance in series with the in-line BVD model.

18. The method of claim 1 , wherein the at least one resonant element comprises a plurality of resonant elements, the at least one other reactive circuit element comprises a plurality of reactive circuit elements, and the at least one acoustic resonator model comprises a plurality of resonator models.

19. The method of claim 18 , further comprising dividing the initial filter circuit design into a plurality of sub-set circuit designs, each of which includes one of the resonant elements and one or more of the plurality of reactive circuit elements, wherein, for each sub-set circuit design, the resonant element and the one or more reactive circuit elements are transformed into a respective one of the acoustic resonator models.

20. The method of claim 1 , further comprising selecting the structural type of each of the at least one resonant element from one of a surface acoustic wave (SAW) resonator, a bulk acoustic wave (BAW) resonator, a film bulk acoustic resonator (FBAR), and a microelectromechanical system (MEMS) resonator.

21. The method of claim 1 , further comprising:
mapping the frequency response requirements to a normalized design space, wherein the circuit element values are normalized values that are determined based on the mapped frequency response requirements; and
unmapping the normalized circuit element values of the acoustic filter circuit design to a real design space.

22. The method of claim 1 , wherein the at least one resonant element comprises a plurality of resonant elements.

23. The method of claim 1 , further comprising:
changing the order in which the plurality of resonant elements in the acoustic filter circuit design are disposed along a signal transmission path to create a plurality of filter solutions;
computing a performance parameter for each of the filter solutions;
comparing the performance parameters to each other; and
selecting one of the filter solutions as the acoustic filter circuit design based on the comparison of the computed performance parameters.

24. The method of claim 1 , further comprising performing an element removal optimization of the acoustic filter circuit design to create the final filter circuit design.

25. The method of claim 24 , wherein the final circuit design comprises a plurality of acoustic resonators, and wherein the difference between the lowest resonant frequency and the highest resonant frequency of the plurality of acoustic resonators in the final filter circuit design is at least one time the maximum frequency separation of a single resonator in the plurality of acoustic resonators.

26. The method of claim 25 , wherein the difference between the lowest resonant frequency and the highest resonant frequency of a plurality of resonators in the final f

Assignees

• Resonant Inc

Inventors

• Turner Patrick J
• Silver Richard N
• Willemsen Cortes Balam Quitze Andres
• Raihn Kurt F
• Fenzi Neal O
• Hammond Robert B

Classifications

• H03H9/465 Primary

  in combination with other electronic elements · CPC title

• H03H9/542

  including passive elements (H03H9/545 takes precedence) · CPC title

• H03H9/6483

  Ladder SAW filters · CPC title

• G06F30/327

  Logic synthesis; Behaviour synthesis, e.g. mapping logic, HDL to netlist, high-level language to RTL or netlist · CPC title

• H03H3/00

  Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators · CPC title