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Design >> Analog Design >> Hoe to find floating nodes and floating gate in a schematic.
https://designers-guide.org/forum/YaBB.pl?num=1361361906

Message started by Superman on Feb 20^th, 2013, 4:05am

Title: Hoe to find floating nodes and floating gate in a schematic.
Post by Superman on Feb 20^th, 2013, 4:05am

Hi friends,
I am new to the digital design field and i m designing flipflop and latches in Cadence environment. It's easy to determine manually the floating nodes and gates for a smaller circuit. I would like to know if there is a way this can be done through codes or any other means for a big circuit consisting more than 100 transistors as it's difficult to detect these manually for such a big circuit. Please help.

Title: Re: Hoe to find floating nodes and floating gate in a schematic.
Post by rf-design on Feb 21^st, 2013, 1:31am

I thought in the past that it would be easy for modified nodal circuit analysis programs to print and plot the node conductance for dc and transient refered to the global gnd-node. I requested this feature about 15 years ago while using SMASH. It is very useful also for general analog circuits which have different switchable operating modes or at least a power down mode. Often the circuit leakage is defined by a floating node and an active gate. The potential on this node is in practice defined by leakage current corners. All designkits which I work with in the past have wrong distributions and could not detect the floating node issues.
About 10 years after the feature request SMASH implement this. But now on the kits does not have the corners and I am not using SMASH anymore.

http://www.dolphin.fr/medal/downloads/pdf/smash/PS-SMASH-5.10.pdf

Title: Re: Hoe to find floating nodes and floating gate in a schematic.
Post by AnilReddy on Feb 21^st, 2013, 5:36am

Hi Superman,

Use Ultrasim simulator. It generates a netlist file just before simulating the circuit which consists of all kinds of inappropriate nodes in the system.

Thanks
Anil