CMS - Filter & Coupling Matrix Synthesis Software

  • A tool tailored for RF/Microwave filter engineers, system designers and students

  • Gives an exact overview of main filter parameters in seconds without complex circuit  models and modeling

  • Designed by filter engineers for filter engineers

Current CMS release: Ver 5.0

Guided Wave Technology's Coupling Matrix Synthesis (CMS) software facilitates synthesis of N+2 coupling matrices for Chebyshev band pass filtering functions, with arbitrary finite-position transmission zeroes.

The CMS software allows placement of complex transmission zeroes, which opens up for group delay shaping.

Main features in Ver 1.0

filter orders up to 12

arbitrary placement of transmission zeroes

complex transmission zeroes - e.g. group delay shaping and analysis

extended parameter plotting options - e.g. mag/ phases of S11 and S21, group delay, table listing

s-parameter file (s2p) generation e.g. as input in system simulator

topology matrix definition of filter circuits - no topology limitations

advanced graph and marker functions - e.g. marker lines & mouse courser read-out

easily re-scalable axes

excellent overview - input and output parameters are viewed at the same time

saving and loading of designs

fast response

integrated manual

intuitive and very user friendly interface
Features added in Ver 2.0:

Check plot of synthesized characteristics, i.e. ability to compare design goal with actual obtained characteristic

The values in the coupling matrix may be edited and the corresponding S-parameter curves plotted.

Coupling matrix values may be displayed in different formats - e.g. bandwidths/ resonance frequencies
Features added in Ver 3.0 & 3.1:

Monte-Carlo Analysis on couplings

Extended Coupling Matrix editing functions by mouse right-click - e.g. sign change, coupling zeroing, etc.

Coupling Matrix export to text file for use in e.g. circuit simulators
Features added in Ver 4.0:

Circuit diagram representation of coupling matrix for better overview.

Loaded Q and stored energy plots for all resonators. Necessary tool for power handling analysis.
Features added in Ver 4.1

Limit lines/filter masks option for fast overview of filter performance

Error indicator showing quality of synthesized filter characteristics

Cursor read-out of stored energy and loaded Q's
Features added in Ver 4.2

Pass/Fail indicators for fast overview of filter compliance

Calculation of load mismatch influence on stored energies

Extended number of topologies in circuit diagram catalog
Features added in Ver 4.3

Deviation from linear phase plot added

Extended coupling matrix editing (e,g, 'slider' for stepless variation of couplings)

Import of coupling matrices

Plot window made scalable by dragging the mouse

Max number of points increased to 801
Features added in Ver 4.4

Max filter order increased from 12 to 14
Features added in Ver 5.0

Spice netlist generation for export of CMS designs into circuit simulators like ADS, Microwave Office, etc.

Extended Marker read-out functionality

     The ability to edit coupling coefficients may be used for:
  • zeroing of very weak couplings in order to see if they can be omitted in a physical filter

  • change of coupling signs

  • investigation of other N+2 coupling matrices e.g. in the literature

  • analysis of where unintended couplings may arise from in a physical filter (often seen as extra notches or asymmetry in measured characteristics).

  • sensitivity analysis of critical couplings


Below: Monte-Carlo analysis on coupling coefficients.
Same variation applied on three different topologies

Two cascaded Triplets Folded                  Cul-de-Sac      

The software gives a fast and accurate overview of

  • Insertion loss

  • Isolation

  • Group delay

  • Phase

  • Coupling coefficients

  • Stored energy per resonator


  • Filter order

  • Return loss

  • Resonator unloaded Q

  • Transmission zero positions

  • Topology



Stored energy plots for each resonator is 'a must' for power handling analysis



CMS is intended for engineers, system designers, sales people, teachers, students and others who are engaged in design and analysis of microwave filters from both component and system point of views. 

The software is intuitive and simple to operate and requires only basic knowledge about filters and filter terms. 

The resonance characteristic of a single resonator in CMS is 100% symmetric and couplings are assumed constant versus frequency. The calculated characteristics are therefore most accurate for narrow band filters (< 10 %) with resonating elements which have symmetric characteristics.

Check out accuracy and utility with the following examples:



 Triplet dielectric resonator filter


 8 pole cross coupled combline filter


 Group delay shaping - introduction+advanced


 Topology investigation by Monte-Carlo Analysis


 Coupling Coefficient Signs - Change of


April 2010      


 Narrow-band Microwave Bandpass 
 Filter Design by Coupling Matrix Synthesis


 The full MWJ article - original document


 Exporting Spice Netlist of CMS filter to circuit simulator


 X-couplings in filters - How do they work?


 Topology and Power Handling

September 2012


 Simplified Power Handling Analysis of
 Microwave Filters


 The full MWJ article - original document

July 2018


 Design of an Ultra-Wideband "Brick Wall" Filter

“My PhD students have been using GWT's coupling matrix software for the design of  Asymmetric   Band pass Filters. The ability to place arbitrary poles has been extremely useful.”

Ian Hunter
Professor and Director of Research
School of Electronic and Electrical Engineering
University of Leeds


“The CMS filter software from Guided Wave Technology has become an invaluable tool in our  filter development. Due to its intuitive and simple user interface the task of simulating and predicting filter performances is no longer restricted to a few specialists in our organization.

The speed and accuracy of this tool allows us to investigate more filter topologies than ever,  thereby assuring that the best filter solution is always found for a given problem.
A highly recommendable tool”

Kristian Lotz
Group Leader, Filters & Combiners
Combilent A/S

  Some customers:


To find out more about the CMS software - take a look in the manual, or browse the keyword index for subjects.

Download a trial version locked to filter order 5 (size: 10 MB).

Current SW: Ver 5.0

IMPORTANT: Once installed - the demo version of CMS must be run as administrator!
                       (Right click on CMS icon and choose: 'Run as administrator')
OS requirements: Windows 7*,8* and 10*
Java must be installed on your system (32 bit JRE)

* Verify on your PC that the Demo version runs satisfactorily before purchasing the full version
  The program must be run as Administrator (right click on CMS icon).

The full version of the CMS software supports filter orders up to 14 and will be locked to the hardware on your PC.
A single user license for the CMS tool costs US$ 1200.-
Discount and upgrade information.

Please contact us for purchasing instructions.