Does anyone know how I can correct my test bench to simulate

Question

Does anyone know how I can correct my test bench to simulate a design taken from magic with a subcircuit

Luis Henrique Rodovalho · Answer

Where is the inverter subcircuit s spice file

Juan Andres · Answer

as the subcircuit is flattened the transistors appear in the spice

Luis Henrique Rodovalho · Answer

The subcircuit has only two terminals VDD and GND The other terminals aren t listed

Luis Henrique Rodovalho · Answer

It seems it is a ring oscillator

Juan Andres · Answer

It is connected inside

Juan Andres · Answer

Yes

Luis Henrique Rodovalho · Answer

```X0 vout1 vout3 GND GND inverter blo X1 vout2 vout1 GND GND inverter blo X2 vout3 vout2 GND GND inverter blo X3 vout3 vout2 VDD VDD inverter blo X4 vout1 vout3 VDD VDD inverter blo X5 vout2 vout1 VDD VDD inverter blo``` It has four terminals here in your testbench file That is why it doesn t run

Luis Henrique Rodovalho · Answer

You should use `X0 VDD GND inverter blo`

Juan Andres · Answer

if I just call GND and VDD which I think is what comes out of the block it simulates but everything stays at 0 even though I initialize to 0

Juan Andres · Answer

what could be the error

Luis Henrique Rodovalho · Answer

You should start any inner node with a preset voltage Use ``` ic X0 vout1 = 1```

Luis Henrique Rodovalho · Answer

Your transient command should be ```tran 0 1n 50n 0 1n uic```

Juan Andres · Answer

what is uic

Luis Henrique Rodovalho · Answer

use initial condition

Juan Andres · Answer

Yes that worked but this command nodeset x2 vout3=0 its same

Luis Henrique Rodovalho · Answer

I don t know if it works for transient simulations It should But it should not be set as 0 I think nodeset and ic act different Nodeset is too find the solution for OP and DC but I don t know if it works as a initial condition for transient sims

Juan Andres · Answer

Well I used nodeset with conditional 0 and it also works

Luis Henrique Rodovalho · Answer

Good Just be aware that for a real design you must consider the width of the metal tracks as they may not be able to handle the current

Juan Andres · Answer

thanks

Juan Andres · Answer

< Luis Henrique Rodovalho> Do you know how I can instantiate the block taking into account that it has 9 outputs

Luis Henrique Rodovalho · Answer

it is the name of the instance begining with x then the names of each node at each pin then the name of the subcircuit