Program Overview

OptiMatch is an interactive impedance match network optimization program for the RF/Microwave engineer. It may be used with either single-ended or complex interstage lumped element or distributed ladder networks. This type of network is commonly found in amplifiers, oscillators, PIN switches, antenna match networks, etc.

Other applications are in the area of device modelling. For instance, one may enter the measured impedance of a transistor, bipolar or FET, which has been derived from vendor s-parameter data, using our SData+ Utility, and then fit that data to a model of the device.

OptiMatch will examine your match network and compute an error function. The error function is a way to quantify the difference between what your circuit does now, and what it would do if it were perfect. It will then selectively change the element values in your network and try to reduce the VSWR to the lowest value possible.

A variant form of the Fletcher-Reeves gradient/linear search algorithm is used. In the Auto mode, one may quickly optimize a wide variety of networks using the default error function and algorithm variables. Using the Expert mode, one may manually change both the error function and the algorithm variables; this may allow you to fine tune for a specific response. How can you make a choice if you don't have one? OptiMatch gives you choices!


Special Features

In addition to the OptiMatch Module, a File Utility allows you to create or make modifications to impedance data files. We call these .IMP files, and they are discussed in Appendix B.

Note that Users of Windows, can, if they wish, use Windows Notepad to edit and/or print .IMP files. However, if you do this, be careful, you cannot change the file format, and you cannot use an editor that adds control characters to the file. You can only use a simple ascii text file editor like NotePad.

A built-in Element Library, (see Appendix A), allows you to create ladder networks using both lumped and distributed elements. You have the option of holding some elements fixed, and letting others vary.

A Unit Utility lets you choose the particular set of units you like best. The default unit set in MHz, nH, pF, and ohms, the same as our other software products. A menu option lets you restore the default set if you should change it.

The Default Utility lets you change the form of the error function and modify certain of the algorithm variables. In some situations, this can have a dramatic effect. For instance, we've been able to turn a parabolic form of VSWR vs frequency response into an equi-ripple response by making one simple algorithm change! Try that with any other optimizer! If changed, a menu option lets you easily restore the default variable set.

The System File, available as a Main Menu choice, lets you check on whether or not you currently have normal or modified units and default variables in place.

Note: Your screen display will be in a black DOS window. We use color boxes, on occasion, to make the menus and tabular output stand out from the white page background.