synthesis and tuning of modern microwave filters and tuning of modern microwave filters vratislav...

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com

Synthesis and Tuning of Modern

Microwave Filters

Vratislav Sokol, CST

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com

Introduction – CST tools, Workflow

Planar filter synthesis (Nuhertz)

Planar filter tuning (BF/SM)

Cavity filter synthesis (Constr. macro)

Cavity filter tuning (BF/GD/invZ, SAM)

Examples

CST key features for the filter design

Conclusion

Agenda

Courtesy of C-COM Ltd.


Construction macro

Cross-coupling

Automatic tuning (SAM)

CST Tools for Microwave Filter Design

NuHertz

Box resonances

Anisotropic dispersive

material properties

Planar Filters

Cavity Filters

Project Template

Arbitrary topology

Full 3D geometry

MOR/FEM solver

Optimizers (e.g. TRF)

Multiphysics (thermal

and mechanical)

Sensitivity and yield

All Structures


Microwave Filter

Planar

Nuhertz Synthesis

Tuning Yield

General Design Input/Output

Coupling (Qext)

Interresonator Coupling

Tuning Yield

Cavity

Construct. Macro Tuning Yield

General Design Input/Output

Coupling (Qext)

Interresonator Coupling

Tuning Yield

Workflow

Type Synthesis Tuning Result


Planar Filter Synthesis


Nuhertz - Filter Quick


Nuhertz Link to CST

layout

CST DS layout

CST MWS model

3D simulation results


First-Iteration Filter

Parameters

Tuning

Prototype

Final design

b=572 m

il

S1=35 mil

S2=44 mil

L=435 mil

Tap= 91.6 mil

a= 512 mil

W= 50 mil goal


Planar Filter – Tuning Parameters

Tuning

Prototype

Final design


CMA Evolution optimizer

global optimizer

very good convergence

Example: Filter Optimization

S1

S2 L3

L2

L1

Frequency in GHz

|S11| i

n d

B

Excellent response

Parameters

Tuning

Prototype

Final design


Trust Region Framework optimizer

local optimizer

can exploit sensitivity information

Example: Filter Optimization

Frequency in GHz

|S11| i

n d

B

Good result in fewer iterations

(20 x faster in this case)

Parameters

Tuning

Prototype

Final design


Port-Tuning Technique

C1 ... L1, C2 ... L2

C3 ... L3, C4 ... S1

C5 ... S2

S-parameters of the filter

including discrete ports

Fast circuit

optimisation

of C1-C5

Update

L1-L3,

S1-S2

OK?

End

3D EM

1

2

3

4 5

See application note on support website!

Parameters

Tuning

Prototype

Final design


TSM–Sensitivity Surrogate Model

'

2

'

1

'

3

'

2

'

111

'

11 2

11

1

11

3

11

2

11

1

11 SSLLLSSS

S

S

S

L

S

L

S

L

S

• CMA-ES Post-processing optimization on the surrogate model using virtual S-parameters.

• Only a few 3D EM simulations needed for getting the final filter response

Parameters

Tuning

Prototype

Final design


Sensitivity Analysis

Parameters

Tuning

Prototype

Final design

Manufacturing tolerances can be taken into account using sensitivity analysis. A face

constraint should be defined for each tolerant parameter (e.g. metallization edges).


97% of the filter samples satisfied the

specification assuming that the manufacturing

tolerance is 0.1 mil (3 x standard deviation).

Parameters

Tuning

Prototype

Final design

Yield Analysis


Cavity Filter Synthesis


3D Filter Macro Interdigital

Combline

Cavity


Cavity Filter Tuning


Direct 3D Optimization (CMA-ES)


Problem: filter tuning requires many manual steps... Tuning of each cavity (peak) is “almost” independent.

Sequential problem!

SAM – Semi-Automatic Filter Tuning

Peak Time-Positions

Coupling elements

Peak Depths Tuning screws


SAM – Semi-Automatic Filter Tuning

1

2

3

4

1 2

3 4

Run tuning steps in sequence iterate.


Examples


Tuning Space Mapping Technique

Courtesy of C-COM Ltd. (Published in RADIOENGINEERING,

VOL. 20, NO. 1, APRIL 2011)


Low-Pass Filter 22.5 GHz

Microstrip Lowpass Filter on RO4350 Substrate


Band-Pass Filter

Miniaturized High-Rejection Ku Band Planar Band-Pass Filter

for Satellite Applications


CST Key Features


Simulation Time Memory

FD - Gen Purpose 19 min 34 sec 2.2 GB

FD- MOR TET 6min 52 sec 3.8 GB

Model courtesy of

THALES ALENIA SPACE

Dr. Marcello Zolesi

FEM MOR Solver (Sensitivity)


EM-field computation

Thermal analysis

Stress analysis /

deformation

Multiphysics Filter Simulation

EM-properties of deformed geometry can be fed into sensitivity analysis


Complete technology for the filter design

Arbitrary filter topology including the X-coupling

Nuhertz link & 3D macro for the filter synthesis

Smart tuning techniques

Multiphysics for high power filters

Very good agreement between simulation and

measurement

Two ANs on filter design & tuning at support web page

Conclusion

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com

Thank you for your attention!

Any questions?

synthesis and tuning of modern microwave filters and tuning of modern microwave filters vratislav...

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