Varying Lowpass Filter
Butterworth filter with varying coefficients
Control System Toolbox / Linear Parameter Varying
The block implements an analog Nth-order Butterworth filter with unit DC gain and varying cutoff frequency that you provide as an input to the block.
Use this block and the other blocks in the Linear Parameter Varying library to implement common control elements with variable parameters or coefficients. For more information, see Model Gain-Scheduled Control Systems in Simulink.
Avoid making the cutoff frequency depend on the block output y. If you have such dependence, the resulting filter causes an algebraic loop, because computing the block output value requires knowing the block output value. This algebraic loop is prone to instability and divergence.
u — Filter input
Lowpass filter input signal.
freq — Cutoff frequency
Filter cutoff frequency, specified in rad/s.
y — Filter output
Lowpass filter output signal.
Filter order — Lowpass filter order
1 (default) | positive integer
Lowpass filter order, specified as a positive integer.
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Introduced in R2017b