Filter Tuning Software (FTS) allows for precise tuning of microwave filters in a post-  production phase, even for a tuning operator with limited experience. The program indicates which tuning elements should be adjusted, in which direction and by what value. An intuitive interface allows for an easy adaptation of new filter types and significant savings of tuning time.



A typical procedure of preparing (customization) FTS for a specified filter is based on a few phases.

Project Wizard – tool used in the customization process of tuning algorithms. It allows its user to enter filter topology, specify filter features, collect required data, specify VNA configuration settings and finally create tuning models. Every new device type requires a new procedure describing a filter with its basic parameters.

Sample Collection – In order to build filter models for later filter tuning, certain samples from the filter need to be collected. These samples are simply characteristics of a filter detuned in a specific manner. This process is crucial for filter tuning quality at a later stage. To collect samples, a precisely tuned filter template is required, the so called “golden filter”, with the best possible margins between the characteristics and the tuning limits. This procedure is performed only once, unless some major changes in the filter construction have been made. Based on the information gathered from the template filter, inverse models are generated, which are later used in the post-production filter tuning.

Building a Filter Model – Once samples are collected for a certain tuning phase (TrimWare or TrimBooster), a filter model can be built. The process of building such a model is automated through the process of applied ending conditions for each training. The term of filter model building process depends on the filter complexity and computer computational power; it can range between a few minutes to hours. After all filter models have been built, green check marks should appear signaling that the project is ready to be used in the tuning process.

Filter Simulation – This is an alternative way of samples collection in order to build the filter model. A set of characteristics which correspond to the detuned state of a filter can be generated by simulation. The procedure is much faster than manual detuning and no golden filters are needed. The only condition required is to collect data of a certain filter which describes its equivalent circuit model. In this version of FTS, parameters of each filter element are located in a special, earlier generated file, which can be next loaded into FTS. After obtaining such information, a set of detuned characteristics corresponding accurately to the real, measured parameters can be generated. At the next step the filter model, as in standard procedure, can be built and used to tune the filter.

FTS tuning procedure consists of three main phases

TrimWare Sequential pre-tuning – All tuning elements are placed in a sequential order into a filter with all tuning elements extracted at the beginning of the process. The process of tuning starts at the specific filter port. It is very important for the analyzed reflection signal to be   measured from this port. Tuning direction is opposite to detuning direction used in customization process. The procedure continues until all screws are fitted. In many cases, a filter can by fully tuned after a single tuning iteration.

TrimBooster – Parallel tuning of pre-tuned filters. This phase consists of changing the position of all tuning screws simultaneously using a continuous display of all error bars for all tuning elements. An operator can tune only one screw at a time. In the process a user makes a choice on a screw to be tuned, finds an appropriate label above the bars and locates a bar which should be minimized to zero, similarly in to TrimWare procedure. All tuning elements and their distances from reference settings are displayed simultaneously. An algorithm generates detuning errors for each tuning element (frequency, coupling, cross-coupling) concurrently.

Fine Tuning – If necessary, a final tuning of a filter, according to specified requirements is made. In this phase, a user chooses a random screw to tune and minimize the overall error.

TrimBooster with TrimWare replaces a tedious process of tuning filters:

  • Simplifies a costly and complex task; as special skills are not required to operate the software
  • Capable of tuning complex precision filters/diplexers
  • Improves a supply chain management through a greater flexibility in production line scheduling
  • Minimizes risks and costs of human errors

Cooperation with Keysight resulted in FTS compatibility with all types of VNAs like ENA, PNA and Handheld FieldFox – a portable analyser.