Fixed-Point Blockset    

Derivative

The FixPt Derivative realization is a masked subsystem that performs discrete-time differentiation. For the this method, differentiation is approximated by the z-domain transfer function

where Ts is the sampling period. The realization is shown below.

As shown in the figure, the transfer function yields the difference equation

where k is the current time step, k - 1 is the previous time step, y(k) is the current output, u(k) is the current input, and u(k - 1) is the input from the previous time step.

Parameters and Dialog Box

The dialog box and parameter descriptions for the derivative realization are given below.

Sample time
The time interval, Ts, between samples
Base data type
The processor's base data type
Accumulator data type
The processor's accumulator data type

Model Design Review

A brief review of the model design is given below. The design criteria reflect the rules presented in Design Rules.


 Derivative Realizations Lead Filter or Lag Filter Realization