Stats

  • Locked Locked
  • Replies 1
  • Subscribers 125
  • Views 16072
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

imax and imelt error in Spectre.

SGGS

While simulating (trans analysis) the circuit of ADC I am  getting the warningat 20ps that

The bulk source junction current exceeds 'imelt'.

The bulk source junction current exceeds 'imax'

 Then at 727ps i am getting the notice that the 

The bulk source junction leaves linearized region 

The bulk source junction current no longer exceeds 'imax' and imelt..

 

 

What these warnings and notices means ...What parameters i should change to avoid these.

I am getting these on only 2 MOSes.

 Thanks,

 

Parents

  • It is telling you that the current was so large that the device behaviour is not modelled properly. This can arise as a result of discontinuties in the models (maybe of other devices) or sometimes because of something which is causing the devices to move out of their correct operating region. Sometimes having excessively large component values (e.g. 1 Henry inductors or 1 Farad capacitors) can cause instability and excessive signal levels.

    Sometimes it's a reflection of problems with the device models, and having insufficient parasitic capacitance to smooth out the discontinuities. Sometimes it's because you've forgotten to connect up the supplies or signals properly though...

    There are many reasons. Reading a book such as the Designer's Guide to SPICE and Spectre by Ken Kundert can help, or you might want to get in contact with Cadence Customer support for some more specific advice.

    Regards,

    Andrew.

Reply

  • It is telling you that the current was so large that the device behaviour is not modelled properly. This can arise as a result of discontinuties in the models (maybe of other devices) or sometimes because of something which is causing the devices to move out of their correct operating region. Sometimes having excessively large component values (e.g. 1 Henry inductors or 1 Farad capacitors) can cause instability and excessive signal levels.

    Sometimes it's a reflection of problems with the device models, and having insufficient parasitic capacitance to smooth out the discontinuities. Sometimes it's because you've forgotten to connect up the supplies or signals properly though...

    There are many reasons. Reading a book such as the Designer's Guide to SPICE and Spectre by Ken Kundert can help, or you might want to get in contact with Cadence Customer support for some more specific advice.

    Regards,

    Andrew.

Children
No Data

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.