Change the model of the zener so that it has zero leakage.

Problem solved!

Of course, in the real world it may not be that simple...

And what do you mean by leakage? Do you mean you want to more defined knee? If so, there are a large number of options, starting with things like a TL431.

Or is it that too much current passes through the zener? Perhaps a higher value resistor in series? Perhaps use a series instead of shunt regulator?

More details might assist us in assisting you.

Hii steve,

Below is a subcircuit of a zener diode. But using it in Hspice is showing lots of error. Can you help me to change this subcircuit to Hspice?

*1 N5071 TEMPERATURE COMPENSATED MODEL

.SUBCKT 1N5071 1 5

D1 13 DFOR

D2 4 2 DBLOCK

IC 1 2 17.8

D3 4 1 DLEAK

*

RS 3 4 .119 TC=-7E-3,-5E-7

RC 2 1 .81 TC=6.52E-4,-3.46E-7

.MODEL DFOR D(IS=4.01E-13 N=1.21 RS=O

+ EG=.958 XTI=6.5)

.MODEL DBLOCK D(IS=lE-12 N=.73 RS=O EG=.1

+ XTI=-3.86 CJO=O)

.MODEL DLEAK D(IS=9.93E-11 Nz58.13 EG=11.41

+ XTI =321)

ENDS