Creating and Manipulating Models

First-Order Hold

First-order hold (FOH) differs from ZOH by the underlying hold mechanism. To turn the input samples into a continuous input , FOH uses linear interpolation between samples.

This method is generally more accurate than ZOH for systems driven by smooth inputs. Due to causality constraints, this option is only available for c2d conversions, and not d2c conversions.

Note    This FOH method differs from standard causal FOH and is more appropriately called triangle approximation (see [2], p. 151). It is also known as ramp-invariant approximation because it is distortion-free for ramp inputs.

Zero-Order Hold

Tustin Approximation