In bidirectional circuits, each connection introduces a time delay of one step.
This was briefly discussed in the Signal processing basics, Transient Sample Mode unit.
This is particularly problematic for circuits like resonators and feedback loops where the
additional time delays have a big impact on the frequency dependent response.
It is recommended to use the delay compensation property to resolve this problem.
The delay compensation digital filter property is available when the number of taps estimation
property is set to group delay, as shown here for the straight waveguide and s-parameter
Set the property value to the integer number of time steps that require delay compensation.
The time delays are removed by shortening the digital filter time domain response.
For example, the ring modulator presented in the Frequency domain simulations section,
has five connections along the ring, and a total delay compensation of 5 is required.
We can split the delay compensation between the two waveguides, such that the delay compensation
value for the right and left waveguides is 2 and 3, respectively.
It is recommended to split the delay compensation between the waveguides rather than apply it
all to one waveguide, with a distribution of 5 and 0, as this minimizes the impact on
the digital filter time domain responses.
If you want to test the delay of a segment of the circuit with non-zero delay compensation,
in the absence of feedback loops, then set the “include delays” property of the analyzer
This is a property of all optical analyzers.