How are the computations performed and what are the limitations?
The computational engine is written Visual Basic .NET (2005) and is really broken down into 3 parts. First, when a simulation is performed, all of the element models are reduced to 2-port S-parameter matrices. Then, they are cascaded to form one S-parameter matrix. Second, the arbitrary sources are created in the time domain and transformed (using FFT) to the frequency domain. Third, the sources, S-parameter matrix, and load characteristics are combined (along with the necessary windows) to compute the desired output parameter. The basic limitation is the fact that the FFT is computed over a fixed (and repeating) length in time. Therefore, sources that have behavior over long periods in time (like Bit-patterns or Steps) can be tricky to deal with. The Bit-pattern and Waveform generator sources do calculate the proper Frequency and Time domain start, stop, and number of point conditions for most applications. However, the user needs to be aware of the total length of their device under
