Vary subcircuit parameter (CMOS) width in hspice

[santoshchiniwar]

hi all
I wanted to vary subcircuit parameter (CMOS) width in hspice...

i have writtern NAND as subcircuit which is called in some other circuit know i have initiated .param width_n and width_p as nmos and pmos width respectively, now i wanted to vary this parameter from other circuit, As shown in the following code. Please correct me if i am wrong in this code ...


.SUBCKT Nand Y A B VDD GND
.param width_N
.param width_P
Mp1 Y A VDD VDD CMOSP L=0.18u W=width_P
Mp2 Y B VDD VDD CMOSP L=0.18u W=width_P
Mn1 Y A X GND CMOSN L=0.18u W=width_N
Mn2 X B GND GND CMOSN L=0.18u W=width_N

.ENDS

** Nand Gates Description

X1 P A B VDD GND Nand
X2 Q A P VDD GND Nand
X3 R B P VDD GND Nand
X4 S Q R VDD GND Nand
X5 C P P VDD GND Nand


VDD VDD GND dc 5v
VA A GND PULSE(0 5 0 0 0 5n 40n)
VB B GND PULSE(0 5 0 0 0 10n 40n)

** Analysis
.TRAN 200p 20n

** Output
.PRINT TRAN V(A) V(B) V(S) V(C)
.alter width 360e-9
width width_N=360e-9 width_P=430e-9
.END

 

[keith1200rs]

subckt parameter varying- help needed

Try it and see.

I think that the .param should be global and therefore not defined in the subcircuit, but I cannot be certain (it is with my simulator - .param within a subcircuit will not be visible outside it). I would have put the .param statements at the end of the definition of the whole circuit.

Also, I would have thought that the .param should define a value so:

.param width_N=0.36u

where you initially define it.

The .alter part should then be
.alter
.param width_N=1u

etc.

I cannot be sure - I don't use Hspice so my method of achieving the same thing would look slightly different.

Keith.

 

[ankitgarg0312]

subckt parameter varying- help needed

correct code is as below :

.SUBCKT Nand Y A B VDD GND
.param width_N=1u $ default value must have to be defined
.param width_P=1u $ default value must have to be defined
Mp1 Y A VDD VDD CMOSP L=0.18u W=width_P
Mp2 Y B VDD VDD CMOSP L=0.18u W=width_P
Mn1 Y A X GND CMOSN L=0.18u W=width_N
Mn2 X B GND GND CMOSN L=0.18u W=width_N

.ENDS

** Nand Gates Description

X1 P A B VDD GND Nand
X2 Q A P VDD GND Nand
X3 R B P VDD GND Nand
X4 S Q R VDD GND Nand
X5 C P P VDD GND Nand


VDD VDD GND dc 5v
VA A GND PULSE(0 5 0 0 0 5n 40n)
VB B GND PULSE(0 5 0 0 0 10n 40n)

** Analysis
.TRAN 200p 20n

** Output
.PRINT TRAN V(A) V(B) V(S) V(C)
.alter width 360e-9
.param width_N=360e-9 width_P=430e-9 $ .param in starting in necessary
.END



***********************
i have updated code , please see remarks that are there starting with symbol $
do let me know if you need more info

Added after 1 minutes:

by default parameters are defined as global so it will pass to all hierarchy.