Slew Rate Block

This function is a simple slew rate block that limits the absolute slope of the output with respect to time to some maximum or value. The actual slew rate effects of over-driving an amplifier circuit can thus be accurately modeled by cascading the amplifier with this model. The units used to describe the maximum rising and falling slope values are expressed in volts or amperes per second. Thus a desired slew rate of 0.5 V/┬Ás will be expressed as 0.5e+6, etc.

The slew rate block will continue to raise or lower its output until the difference between the input and the output values is zero. Thereafter, it will resume following the input signal, unless the slope again exceeds its rise or fall slope limits. The range input specifies a smoothing region above or below the input value. Whenever the model is slewing and the output comes to within the input + or - the range value, the partial derivative of the output with respect to the input will begin to smoothly transition from 0.0 to 1.0. When the model is no longer slewing (output = input), dout/din will equal 1.0.

Port Table

Description Direction Default Type Allowed Types Vector Vector Bounds Null Allowed
Input IN v v,vd,i,id,vnam NO   NO
Output OUT v v,vd,i,id NO   NO

Parameter Table

Name Description Data Type Default Value Limits Vector Vector Bounds Null Allowed
rise_slope rising slew limit Real 1.0e-9   NO   YES
fall_slope falling slew limit Real 1.0e-9   NO   YES


al5 1 2 slewl
.model slewl slew(rise_slope=0.5e6 fall_slope=0.5e6)

See also

XSPICE Devices
XSPICE Code Models