SIMPLIS Parts

Track and Hold for Discrete Filters

The Track and Hold for Discrete Filters models an analog tracking sample and hold. Whenever the clock is high, the output voltage tracks the input voltage. When the clock transitions low, the output is held at the last sampled value. This behavior is different than the Sampler and Zero Order Hold, which samples on a TRIG edge. As with the other devices in the Discrete Time Filter category, the Track and Hold for Discrete Filters is compatible with the SIMPLIS POP and AC Analyses.

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Model Name:

Track and Hold for Discrete Filters

Simulator:

This device is compatible with the SIMPLIS simulator.

Parts Selector
Menu Location:

Digital Functions | Discrete Time Filters

Symbol Library:

None - the symbol is automatically generated when placed or edited.

Model File:

None - the device model is generated before simulation.

Subcircuit Name:

SIMPLIS_DIGI1_D_DF_TNH_Y

Symbols:

Multiple Selections:

Only one device at a time can be edited.

Editing the Track and Hold for Discrete Filters

To configure the track and hold for discrete filters, follow these steps:

  1. Double click the symbol on the schematic to open the editing dialog to the Parameters tab.
  2. Make the appropriate changes to the fields described in the table below the image.
Label Parameter Description

Acquisition Time

Filter acquisition time in seconds

Initial Condition

Initial condition of the filter output

Examples

The test circuit used to generate the waveform examples in the next section can be downloaded here: simplis_038_tandhold_example.sxsch.

Track and Hold For Discrete Filters Example Schematic

Waveforms

In the circuit example, a 100kHz sine wave with a 1V amplitude ( +/- 1V peak ) is applied to the input of the track and hold. The clock has a frequency of 1MHz and a duty cycle of 50%. The output voltage tracks the input voltage when the clock is high and holds the last input state when the clock transitions low.

The following AC waveforms confirm the DC gain is 0dB as expected. The phase change though a track and hold will change with the duty cycle of the applied clock.

Subcircuit Parameters

Because this track and hold for discrete filters model is generated by a template script when the simulation is executed, a fixed model cannot be inserted into a netlist. The template script for this device is simplis_make_digital_filter_model.sxscr, which you, as a licensed user, can download in a zip archive of all built-in scripts.

To download this zip file, follow these steps:

Note: You will be prompted to log in with the user name and password given to you when you registered.

  1. Click here to go to the product-installation page on the SIMetrix website.
  2. Click Download Links in the first paragraph of the product-installation web page.
  3. Scroll down to the Built-in Scripts section.
  4. Right click on Download and select Save target as..., and then navigate to a location on your computer to save the zip file.