PSpice User Guide

PSpice User Guide

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PSpice A/D User Guide Analog behavioral modeling October 2019 347 Product Version 17.4-2019 © 2022 All Rights Reserved. Interpolation is performed between entries. Magnitude is interpolated logarithmically; phase is interpolated linearly. For frequencies outside the table's range, 0 (zero) magnitude is used. This characteristic can be used to impose an upper and lower limit on the output. The DELAY property increases the group delay of the frequency table by the specified amount. The delay term is particularly useful when a frequency table device generates a non-causality warning message during a transient analysis. The warning message issues a delay value that can be assigned to the part's DELAY property for subsequent runs, without otherwise altering the table. The output of the part depends on the analysis being done. For DC and bias point, the output is the zero frequency magnitude times the input voltage. For AC analysis, the input voltage is linearized around the bias point (similar to EVALUE and GVALUE parts, Modeling mathematical or instantaneous relationships on page 364). The output for each frequency is then the input times the gain, times the value of the table at that frequency. For transient analysis, the voltage is evaluated at each time point. The output is then the convolution of the past values with the impulse response of the frequency response. These rules follow the standard method of using Fourier transforms. We recommend looking at one or more of the references cited in Frequency-domain device models on page 370 for more information. Note: The table's frequencies must be in order from lowest to highest. The TABLE part provides one input and one output. Example A device, ELOFILT, is used as a frequency filter. The input to the frequency response is the voltage at net 10. The output is a voltage across nets 5 and 0. The table describes a low pass filter with a response of 1 (0 dB) for frequencies below 5 kilohertz and a response of 0.001 (-60 dB) for frequencies above 6 kilohertz. The phase lags linearly with frequency. This is the same as a constant time delay. The delay is necessary so that the impulse response is causal. That is, so that the impulse response does not have any significant

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