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Hello. I'm doing a project with sky130 technology and I'm having difficulty exporting the spice mode...
# sky130
e
Hello. I'm doing a project with sky130 technology and I'm having difficulty exporting the spice model from xschem to magic correctly. I had already carried out this procedure with a smaller hierarchy block smoothly running up to LVS, but now I had to do it from the top, instantiating the blocks, I was unable to do the export correctly and LVS failed. Can anybody help me?
comp.out
This is the top photo.
m
ldo_gnd
is shorted to 
ldo_gnd
Copy code
Net: ldo_out                               |Net: ldo_out                               
  Ota_esq/Vin = 1                          |  Ota_esq/Vin = 1                          
  sky130_fd_pr__nfet_03v3_nvt/3 = 15       |  sky130_fd_pr__nfet_03v3_nvt/3 = 1        
  sky130_fd_pr__nfet_03v3_nvt/4 = 30       |  sky130_fd_pr__nfet_03v3_nvt/4 = 1        
  sky130_fd_pr__nfet_03v3_nvt/1 = 15       |                                           
  Ota_esq/VSS = 1                          |                                           
                                           |                                           
Net: ldo_ref                               |Net: ldo_ref                               
  Ota_esq/Vip = 1                          |  Ota_esq/Vip = 1                          
                                           |                                           
Net: ldo_ibias                             |Net: ldo_ibias                             
  Ota_esq/Ibias = 1                        |  Ota_esq/Ibias = 1                        
                                           |                                           
(no matching net)                          |Net: ldo_gnd                               
                                           |  Ota_esq/VSS = 1
probably through the psubstrate. Do you really want to connect the bulk terminal (psubstrate = ground) of the nfet in 
LDO
to 
ldo_out
? If you do, you probably want to isolate it in a deep nwell.
Also, what command are you using to run lvs? You might be missing the setup file.
e
Here is the command I am using.
Is this your suggestion?
Something I noticed is that when importing spice pro magic. The AmpOp cell is not instantiated inside the top. As if there were problems with the import.
m
I think reading spice into magic only instantiates the primitive devices. @Tim Edwards?
e
I believe it must be related to hierarchy, especially with the generation in xschem, because I was able to import and perform the LVS successfully in the individual AmpOp cell.
m
netgen command looks good.
Is this your suggestion?
Yes, connect the nfet bulk to ground.
e
I tested the connection change, but I still wasn't able to import it correctly.
m
Connection change is for LVS. You may not be able to import macros - just primitive devices. Is the primitive nfet instantiated when you read spice? Maybe the parameters (nf=30 W=300 L= 0.5) exceed the device generator limits.
Since there’s only one device, might be easier to use the device generator manually.
e
The transistor is instanced but the OpAmp does not appear in the LDO Layout
m
I think reading spice into magic only instantiates the primitive devices.
You may not be able to import macros - just primitive devices.
e
I managed to make the connections by correcting the generation problems, but the LVS result is the one shown.
m
@EDSON ALVES DA SILVA Can you share your lvs result, extracted netlist, and schematic netlist?
e
Here are the Netlist. I renamed the netlist generated from xschem.
LDO_xschem.spiceLDO.spice
m
@EDSON ALVES DA SILVA I only see 4 pins in the extracted layout. Do you have a 
ldo_gnd
pin? If you do, it might be shorted to something 
ldo_out
. Look at the messages near the end of extraction. Did you change the layout nmos bulk connection?
e
I managed to solve the problems. 1- When developing the AmpOp Layout, some transistor cells changed their name. The result is that during spice import, the program saw the difference and tried to import new transistors and ended up getting an error when finding known cells, messing up the import. 2- As you mentioned (@Mitch Bailey) the nmos transistor of w=300 had the wrong measurements and the program was not showing an error when importing, but this was damaging the import, which prevented the program from instantiating the AmpOp.
👍 1
Thank you very much @Mitch Bailey
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