SPICE netlist for Resistor subckt

Hi,

I am working on design simulation using Nanosim, and am facing this error below.
WARNING:NanoSim:0x202040aa:s is unused port in instance "xrx3/x12/r0" of subckt "rdiffp3".

The netlist used for Nanosim was obtained from Calibre PEX.
When I referred to the instance "xrx3/x12/r0" in the hspice netlist, it was given as.

XrX3/X12/R0 N_X3/X12/11_X3/X12/R0_pos N_GND!_X3/X12/R0_neg RDIFFP3 w=1.6e-06
+ l=1.57e-05 $SUB=N_VDD!_X3/X12/R0_sub

But the resistor subckt "rdiffp3" is defined in the library as,

.SUBCKT RDIFFP3 D B S W=1e-6 L=1e-6
J1 D B S RDIFFP3
....

I am assuming D, B, S refer to Drain, Body and Source as for a voltage controlled JFET resistor.

So from the netlist instance can I take
D = N_X3/X12/11_X3/X12/R0_pos
S = N_GND!_X3/X12/R0_neg
B = N_VDD!_X3/X12/R0_sub (which is mentioned as $SUB)

Is this assumption right?

I would create a subcircuit symbol with the correct number of nodes so I could use the foundry model as it is, but you could do it your way.

The nodes of a JFET are drain gate source with the gate being "bulk" for the RDIFFP resistor and connected to substrate, so your connections look correct to me.

Keith.

Hi Keith,

Thanks for your reply. If had to change the library instead of the netlist, how should I go about it.

How should I add the "$SUB" parameter in the netlist to the library, in the below statement.

.SUBCKT RDIFFP3 D S W=1e-6 L=1e-6

regards,
saravanan

I don't use Nanosim so I don't know how you create new components, but in my simulator you just draw a shape, add pins and a model name and specify the pin names & order. I have a symbol I created like this:



I should have drawn it more like a resistor! But anyway, it makes it easier then when I switch to another process and I can use the same symbol for any other well resistors by just changing the model name.

Keith.

Oh. ok.
Thanks for the reply.

regards,
saravanan