NAME_TABLE:

C_Function_Name: cm_d_dt

Spice_Model_Name: d_dt

Description: "time-derivative block"

PORT_TABLE:

Port Name: in out

Description: "input" "output"

Direction: in out

Default_Type: v v

Allowed_Types: [v,vd,i,id] [v,vd,i,id]

Vector: no no

Vector_Bounds: - -

Null_Allowed: no no

PARAMETER_TABLE:

Parameter_Name: gain out_offset

Description: "gain" "output offset"

Data_Type: real real

Default_Value: 1.0 0.0

Limits: - -

Vector: no no

Vector_Bounds: - -

Null_Allowed: yes yes

PARAMETER_TABLE:

Parameter_Name: out_lower_limit out_upper_limit

Description: "output lower limit" "output upper limit"

Data_Type: real real

Default_Value: - -

Limits: - -

Vector: no no

Vector_Bounds: - -

Null_Allowed: yes yes

PARAMETER_TABLE:

Parameter_Name: limit_range

Description: "upper & lower limit smoothing range"

Data_Type: real

Default_Value: 1.0e-6

Limits: -

Vector: no

Vector_Bounds: -

Null_Allowed: yes

• Description:
  The Differentiator block is a simple derivative stage that approximates the time derivative of an input signal by calculating the incremental slope of that signal since the previous time point. The block also includes gain and output offset parameters to allow for tailoring of the required signal, and output upper and lower limits to prevent convergence errors resulting from excessively large output values. The incremental value of output below the output upper limit and above the output lower limit at which smoothing begins is specified via the limit range parameter. In AC analysis, the value returned is equal to the radian frequency of analysis multiplied by the gain.
  Note that since truncation error checking is not included in the d_dt block, it is not recommended that the model be used to provide an integration function through the use of a feedback loop. Such an arrangement could produce erroneous results. Instead, you should make use of the "integrate" model, which does include truncation error checking for enhanced accuracy.

Example SPICE Usage:

a12 7 12 slope_gen

.

.

.model slope_gen d_dt(out_offset=0.0 gain=1.0

+ out_lower_limit=1e-12 out_upper_limit=1e12

+ limit_range=1e-9)