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What is a convergence problem? My circuit code is below and when I simulate it is saying that the NMOS transistors MPDA and MPDB are not converging. See the following screenshot:

code and problem

Here's the netlist:

V1 1 0 DC 5V 
V2 2 0 PULSE(0 5 3ns 3ns 3ns 20ns 40ns)
V3 3 0 PULSE(0 5 6ns 3ns 3ns 20ns 40ns)
CL 4 0 0.15PF
MPUA 4 2 1 1 IRF150
MPUB 4 3 1 1 IRF150
MPDA 4 2 5 0 IRF250
MPDB 5 3 0 0 IRF250
.MODEL IRF250 NMOS (level=3 w=4u l=3u vto=1.0 tox=470e-10 nsub=38e14 cj=160e-6 
+cjsw=430e-12 mj=0.5 mjsw=0.33 kp=30e-6)
.MODEL IRF150 PMOS (level=3 w=10u l=3u vto=-1.0 tox=470e-10 nsub=8.7e14 cj=100e-6 
+cjsw=180e-12 mj=0.5 mjsw=0.33 kp=12e-6)
.TRAN 1ns 80ns
.PROBE V(2,0) V(3,0) V(CL) ID(MPDA) ID(MPUA)
.END
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  • \$\begingroup\$ Did you enter a schematic in the capture program or did you enter your netlist by hand? In the former case a screenshot of the schematic could help. Moreover, post a text version of your netlist, so that we can copy and paste it in our simulation programs instead of copying by hand the netlist in that tiny image. \$\endgroup\$ – Lorenzo Donati -- Codidact.org Jun 28 '15 at 9:22
  • \$\begingroup\$ @Lorenzo the netlist: V1 1 0 DC 5V V2 2 0 PULSE(0 5 3ns 3ns 3ns 20ns 40ns) V3 3 0 PULSE(0 5 6ns 3ns 3ns 20ns 40ns) CL 4 0 0.15PF MPUA 4 2 1 1 IRF150 MPUB 4 3 1 1 IRF150 MPDA 4 2 5 0 IRF250 MPDB 5 3 0 0 IRF250 .MODEL IRF250 NMOS (level=3 w=4u l=3u vto=1.0 tox=470e-10 nsub=38e14 cj=160e-6 +cjsw=430e-12 mj=0.5 mjsw=0.33 kp=30e-6) .MODEL IRF150 PMOS (level=3 w=10u l=3u vto=-1.0 tox=470e-10 nsub=8.7e14 cj=100e-6 +cjsw=180e-12 mj=0.5 mjsw=0.33 kp=12e-6) .TRAN 1ns 30ns .PROBE V(2,0) V(3,0) V(CL) ID(MPDA) ID(MPUA) .END \$\endgroup\$ – Enthusiast Jun 28 '15 at 10:27
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I imported the netlist into LTSpice and it worked ok (I only had to rename V(CL) to V(4) in the .PROBE directive, since LTSpice didn't recognize that syntax to specify the voltage across the cap):

enter image description here

The results of the simulation are shown below:

enter image description here

Therefore there is nothing inherently wrong with your netlist. Probably the simulation engine of PSPICE didn't succeed to find a solution for the equations. Try to fiddle with the simulation accuracy parameters (I don't use PSPICE, so I cannot help with that).

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  • \$\begingroup\$ thanks....@lorenzo donati...i have found a solution...if the accuracy of the voltage and current decrease..then it works... \$\endgroup\$ – Enthusiast Jul 1 '15 at 11:26
  • \$\begingroup\$ @Enthusiast Ok, good! If my answer helped you in finding the solution, please consider upvoting or marking it as accepted. This is how this site works, and helps other people finding/evaluating good answers. \$\endgroup\$ – Lorenzo Donati -- Codidact.org Jul 1 '15 at 13:01

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