NAME_TABLE:

C_Function_Name: cm_climit

Spice_Model_Name: climit

Description: "controlled limiter block"

PORT_TABLE:

Port_Name: in cntl_upper

Description: "input" "upper lim. control input"

Direction: in in

Default_Type: v v

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

Vector: no no

Vector_Bounds: - -

Null_Allowed: no no

PORT_TABLE:

Port_Name: cntl_lower out

Description: "lower limit control input" "output"

Direction: in out

Default_Type: v v

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

Vector: no no

Vector_Bounds: - -

Null_Allowed: no no

PARAMETER_TABLE:

Parameter_Name: in_offset gain

Description: "input offset" "gain"

Data_Type: real real

Default_Value: 0.0 1.0

Limits: - -

Vector: no no

Vector_Bounds: - -

Null_Allowed: yes yes

PARAMETER_TABLE:

Parameter_Name: upper_delta lower_delta

Description: "output upper delta" "output lower delta"

Data_Type: real real

Default_Value: 0.0 0.0

Limits: - -

Vector: no no

Vector_Bounds: - -

Null_Allowed: yes yes

PARAMETER_TABLE:

Parameter_Name: limit_range fraction

Description: "upper & lower sm. range" "smoothing %/abs switch"

Data_Type: real boolean

Default_Value: 1.0e-6 FALSE

Limits: - -

Vector: no no

Vector_Bounds: - -

Null_Allowed: yes yes

• Description:
  The Controlled Limiter is a single input, single output function similar to the Gain Block. However, the output of the Limiter function is restricted to the range specified by the output lower and upper limits. This model will operate in DC, AC, and Transient analysis modes. Note that the limit range is the value below the (cntlupper) limit and above the (cntllower) limit at which smoothing of the output begins (minimum positive value of voltage must exist between the (cntlupper) input and the (cntllower) input at all times). For this model, then, the limit range represents the delta with respect to the output level at which smoothing occurs. Thus, for an input gain of 2.0 and output limits of 1.0 and -1.0 volts, the output will begin to smooth out at (\pm)0.9 volts, which occurs when the input value is at (\pm)0.4. Note also that the Controlled Limiter code tests the input values of (cntlupper) and (cntllower) to make sure that they are spaced far enough apart to guarantee the existence of a linear range between them. The range is calculated as the difference between ((cntlupper - upperdelta - limitrange)) and ((cntllower + lowerdelta + limitrange)) and must be greater than or equal to zero. Note that when the limit range is specified as a fractional value, the limit range used in the above is taken as the calculated fraction of the difference between (cntlupper) and (cntllower). Still, the potential exists for too great a limit range value to be specified for proper operation, in which case the model will return an error message.

Example SPICE Usage:

a6 3 6 8 4 varlimit

.

.

.model varlimit climit(in_offset=0.1 gain=2.5 upper_delta=0.0

+ lower_delta=0.0 limit_range=0.10 fraction=FALSE)