Go to www.awrcorp.com
Back to search page Click to download printable version of this guide.

Nonlinear Resistor: NLRESA

Symbol

Summary

The Cadence® NLRESA element is a replacement for NLRES. It also provides most of the functionality found in Spectre's resistor and phy_res elements, and in HSPICE's Wire RC model. This device has three different modes of operation: wire, physical resistor, and nonlinear resistor. In the wire mode of operation, NLRESA supports most of the functionality available in both Spectre's resistor and in HSPICE's Wire RC model. In the phy_res mode of operation, NLRESA implements Spectre's phy_res element. In the nonlinear resistor mode (default), NLRESA behaves very much as its predecessor NLRES. The topology underlying each mode of operation is reflected by the device symbol.

Parameters

Name Description Unit Type Default
ID Element ID Text R1
TYPE Device type   2
SUBTYPE Substrate type   0
*R Resistance Resistance  
*MULT Multiplicity factor   1
*NFLAG Noise flag   On
*L Resistor length Length  
*W Resistor width Length  
*TC1 Linear temperature coefficient of resistance   0
*TC2 Quadratic temperature coefficient of resistance   0
*TNOM Parameter extraction temperature Temperature 26.85DegC
*TEMP Device temperature Temperature _TEMP
*C Capacitance Capacitance  
*TC1C Linear temperature coefficient of capacitance   0
*TC2C Quadratic temperature coefficient of capacitance   0
*RSH Sheet resistance    
*ETCH Width narrowing due to etching per side Length 0
*ETCHL Length narrowing due to etching per side Length 0
*ETCHC Width narrowing due to etching per side for capacitances Length  
*ETCHLC Length narrowing due to etching per side for capacitances Length  
*COEFFS Vector of polynomial coefficients    
*NONLINFORM Form of the nonlinear resistance   0
*CJ Bottom capacitance    
*CJSW Sidewall capacitance    
*FC Junction bottom capacitor forward-bias threshold   0.5
*FCSW Junction sidewall capacitor forward-bias threshold   0.5
*MJ Junction bottom grading coefficient   0.5
*MJSW Junction sidewall grading coefficient   0.33e-13
*PB Junction bottom built-in potential   0.8
*PBSW Junction sidewall built-in potential   0.8
*THICK Dielectric thickness    
*DI Relative dielectric constant    
*IS Saturation current Current  
*JS Saturation current density    
*N Emission coefficient   1
*CRATIO Capacitance ratio    
*KF Flicker (1/f) noise coefficient   0
*AF Flicker (1/f) noise exponential term   2
*THIRD_TERMINAL Third terminal connection   Grounded

Operating Points

The following letter pairs have been used to identify the NL branches: pn, p0 and n0. Here pn, p0 and n0 correspond to the branches defined between the positive and negative terminals, positive and ground terminals, and negative and ground terminals, respectively. These names are used to identify branch related operating point information, i.e., branch voltages, currents, etc.

Parameter Description
gpn (Conductance) Main branch conductance
gp0 (Conductance) Positive terminal to ground conductance
gn0 (Conductance) Negative terminal to ground conductance
cp0 (Capacitance) Positive terminal to ground capacitance
cn0 (Capacitance) Negative terminal to ground capacitance

Implementation Details

The TYPE parameter allows you to choose between three different modes of operation: wire, physical resistor, and, non-linear resistor (resistor). The SUB_TYPE parameter, available in the physical resistor mode of operation only, allows you to choose the substrate type. Possible values are n, p or poly. Finally, the THIRD_TERMINAL parameter, available in the physical resistor and wire modes of operation only, controls whether the third terminal is grounded, or can be externally accessed.

In the nonlinear resistor mode (default), NLRESA behaves very much as its predecessor NLRES, but there are some differences worth mentioning: polynomial coefficients are entered as a vector, COEFF={C0, C1, C2, ...}, instead of as individual parameters; and; the non-linearity described by the coefficients can be either a resistance, or, a conductance. Also, NLRESA accounts for noise, both thermal and Flicker.

When NONLINFORM is set to conductance the resistive branch of the element has following I/V relationship:

When NONLINFORM is set to resistance, it has the following form:

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: NLRESA 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 RES or REST.

Legal and Trademark Notice