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Resistor Model

Type Name: r

The resistor model consists of process-related device data that allow the resistance to be calculated from geometric information and to be corrected for temperature. The parameters (multiple names are aliases) available are:

Resistor Model Parameters
name parameter units default example
tc1, tc, tc1r first order temperature coeff. $ \Omega$/C 0.0 -
tc2, tc2r second order temperature coeff. $ \Omega$/C2 0.0 -
rsh sheet resistance $ \Omega$/$ \Box$ - 50
defl, l default length M 0 2e-6
defw, w default width M 0 2e-6
dl, dlr length reduction due to etching M 0 1e-7
narrow, dw narrowing due to side etching M 0 1e-7
tnom, tref parameter measurement temperature C 25 50
temp default instance temperature C 25 50
kf flicker noise coefficient   0  
af flicker noise exponent of current   2  
ef flicker noise exponent of frequency   1  
wf flicker noise exponent of width   1  
lf flicker noise exponent of length   1  

The sheet resistance is used with the etch reduction parameters and l and w from the resistor element line to determine the nominal resistance by the formula

R = rsh . (l - dl)/(w - narrow).

The parameters defw and defl are used to supply default values for element w and l if not specified on the device line. A fatal error is produced if the resistance can't be determined from given parameters.

After the nominal resistance is calculated, it is adjusted for temperature by the formula:

R(temp) = R(tnom) . (1 + tc1 . (temp-tnom) + tc2 . (temp-tnom)2)

The flicker noise capability can be used in noise analysis. This requires that kf, l, and w be specified. To use, the instance line must reference a model, but also can have a resistance specified which will override model calculation of resistance.

Flicker noise model:

Noise = (KF . IAF)/(LeffLF . WeffWF . fEF)

Param Description Units
Noise Noise spectrum density A2Hz
I Current A
Leff Eff length (L-DL) M
Weff Eff width (W-DW) M
f Frequency Hz
Param Description Default, Range
KF Flicker noise coefficient 0, > = 0
AF Exponent of current 2, > 0
LF Exp. of eff. length 1, > 0
WF Exp. of eff. width 1, > 0
EF Exp. of frequency 1, > 0


next up previous contents index
Next: Switches Up: Passive Element Lines Previous: Resistors   Contents   Index
Stephen R. Whiteley 2012-09-24