+ Post New Thread
Results 1 to 3 of 3
  1. #1
    Junior Member level 1
    Points: 368, Level: 4

    Join Date
    Nov 2017
    Posts
    17
    Helped
    0 / 0
    Points
    368
    Level
    4

    Zero diagonal found in Jacobian error in simulation the DAC?

    I face with the problem Zero diagonal found in Jacobian when I run the simulation for DAC with bridge capacitor architechture. The error happens when I use MIM capacitor in the PDK. However, the simulation is run succesfully when I use ideal capacitor. How can I deal with this issue? I use IC 5141 simulator.
    Click image for larger version. 

Name:	Screenshot_5.png 
Views:	7 
Size:	28.7 KB 
ID:	152396
    Click image for larger version. 

Name:	Screenshot_6.png 
Views:	5 
Size:	30.3 KB 
ID:	152397

    •   AltAdvertisment

        
       

  2. #2
    Full Member level 1
    Points: 580, Level: 5

    Join Date
    Jan 2019
    Posts
    118
    Helped
    20 / 20
    Points
    580
    Level
    5

    Re: Zero diagonal found in Jacobian error in simulation the DAC?

    check the quality of the MIMs capacitor model in a simple circuit, like an RC low pass filter.
    then try a more complex circuit -say throw in an op amp and a second MIM capacitor, say a SallenKey filter.

    reduce the number of capacitors - try just the LSB or MSB.



    •   AltAdvertisment

        
       

  3. #3
    Advanced Member level 5
    Points: 38,586, Level: 48

    Join Date
    Mar 2008
    Location
    USA
    Posts
    6,245
    Helped
    1809 / 1809
    Points
    38,586
    Level
    48

    Re: Zero diagonal found in Jacobian error in simulation the DAC?

    Zero diagonal IME is from floating nodes (infinite resistance
    transforms to zero conductance). This can be from "buried"
    connectivity that hides at the bottom level of subcircuits
    or even in compact-model instances that leave "code stubs"
    if you fail to provide params that would enable "closure".

    Be sure you have filled any instance properties that express
    connectivity such as well and substrate net connections.



--[[ ]]--