## Cxxxxxxx

Capacitor: This device is translated as a capacitor. For information on the capacitor model, refer to [C_Model:Capacitor Model].

##### Example SPICE Command Line:

c1 1 2 1pF

##### SPICE dialect and netlist syntax:

Spice2/3:

cidn1n2[valuemname] [l=l] [w=w] [ic=ic]

PSpice:cidn1n2[mname]value[ic=ic]

HSpice:cidn1n2[mname] [c=]value[[tc1=]tc1[[tc2=]tc2]] + [scale=scale] [ic=ic] [m=mult] [w=w] [l=l] [dtemp=dtemp]

##### ADS Netlist Syntax:

Without model referenced:

C:cidn1n2C=value[_M=mult]

With model referenced:

mname_

:cidn1n2[C=value] [Length=l] [Width=w] [InitCond=ic]

+ [TC1=tc1] [TC2=tc2] [Temp=temp+(dtemp)] [M=_mult]

##### ADS Schematic Symbol:

##### Instance Parameters:

cid= Capacitor element name

mname= Model name

n1= Positive node

n2= Negative node

value= Capacitance in farads

l= Length in meters

w= Width in meters

ic= The optional initial condition (time-zero) value of capacitor voltage (in volts). The initial condition (if any) applies only if the UIC option is specified on the .TRAN control line.

tc1= Temperature coefficient per degrees celsius.

tc2= Temperature coefficient per degrees celsius squared.

scale= Element scale factor.

mult= Multiplier used to simulate multiple parallel devices.

dtemp= Element temperature difference with respect to circuit temperature.

##### Comments:

**HSpice:** If the value of C is an expression which is a function of node voltages or independent variables, then the component is a dependent capacitor. In ADS, the component is represented by a Symbolically Defined Device (SDD).

If one of the SDD parameters uses a variable containing node voltages, the translator needs to look up the node voltages on the resultant SDD to convert them to the correct ADS syntax and update the variable expression. For instance, the node voltage described as v(nodeX) in HSpice must be converted to _v1, if the first pair of nodes on the SDD is (node1, 0).

For translation purposes of this special case, the SDD and the variable used by it are expected to be defined in the same subcircuit, with the variable being used by only one SDD. If the variable were defined globally or used by different SDDs, the node voltage variables (_v1, etc.) might not match up correctly. For example, in the case described above one SDD might have (nodeX,0) as the first pair of nodes (_v1), while another SDD might have (nodeX,0) as the 2nd pair of nodes (_v2). The translator would not be able to replace v(nodeX) in the variable expression to define both SDDs correctly at the same time.

If this SDD is not found in the same subcircuit as the variable expression, a warning message will be written to the log file *nettrans.log* . Also, the expression will not be converted automatically, and it will have to be fixed manually before simulation is attempted.

If SCALE is specified, Value=Value*scale

If dtemp is provided, Temp=temp+dtemp

**Translator Limitations:** Functionality is available in ADS but not yet supported by the Netlist Translator. Workarounds are provided below.

HSpice:

**1)** Nonlinear capacitor cid n1 n2 poly c0 c1 c2...

This is supported by ADS as a component called NonlinC. The ADS Netlist Syntax should be:

NonlinC:cid n1 n2 coef=list(c0 c1 c2...) [ic=ic]

**2)** cid n1 n2 c='equation' ctype=[0|1]

This syntax requires a Symbolically Defined Device (SDD) in ADS if ctype=0. This is not currently handled by the translator. Please contact customer support for assistance in writing the SDD to represent the voltage across the capacitor.

The Netlist Translator fails to recognize the capacitor model in the following syntax:

c1 1 2 cmodel

The translator assumes that it is a variable name for the capacitance value. To correct your imported schematic, manually move the model name to the parameter Model. To correct the ADS Netlist, use the following netlist syntax:

cmodel:c1 1 2 [param=value]*

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