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Nonlinear Capacitor: NLCAPA

Symbol

Summary

NLCAPA is a replacement for NLCAP. It also provides all of the functionality found in Spectre's capacitor, or HSPICE's C device.

Parameters

Name Description Unit Type Default
ID Element ID Text C1
*L Capacitor length Length 0
*W Capacitor width Length 0
*AREA Capacitor area    
*PERIM Capacitor perimeter    
MULT Multiplicity factor   1
*TC1 Linear temperature coefficient of capacitance   0
*TC2 Quadratic temperature coefficient of capacitance   0
*TNOM Parameter extraction temperature Temperature 26.85DegC
*TEMP Device temperature Temperature _TEMP
C Capacitance Capacitance  
*ETCH Width narrowing due to etching per side Length 0
*COEFFS Vector of polynomial coefficients    
*CJ Bottom capacitance density    
*CJSW Sidewall capacitance density    
*THICK Dielectric thickness    
*DI Relative dielectric constant    

Operating Points

The letter pair pn identifies the only NL branch of this model. Consequently, Vpn and Ipn identify voltage and current of this branch, respectively.

Parameter Description
cap (Capacitance) Element capacitance

Implementation Details

Several differences are noticed when NLCAPA is compared with its predecessor NLCAP: polynomial coefficients are entered as a vector, COEFF={C0,C1,...}, instead of as individual parameters; there is temperature compensation support, in terms of parameters TC1 and TC2; and; the capacitance may be entered directly, or, calculated it from the physical length and width of the capacitor. In either case, the capacitance may be a function of temperature, or, applied voltage.

The capacitance is given by

And the corresponding charge by

Layout

This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

Recommendations for Use

NOTE: NLCAPA is implemented as a nonlinear device in harmonic balance simulations, independently of whether the polynomial truly describes a nonlinear device. As a result, from a performance standpoint, it is advisable to limit the use of this element to those cases where the desired functionality cannot be implemented by a simpler linear element, such as CAP.

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