[SOLVED]measuring the parasitic capacitance at a certain node in cadence

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amr.maghraby

Junior Member level 2
is it possible to measure the parasitic capacitance at a certain node in a schematic in cadence??

Yes, it is.

pancho_hideboo

is it possible to measure the parasitic capacitance at a certain node in a schematic in cadence??
I don't know what you want to mean by "in a schematic in cadence" at all.

However Synopsys HSPICE have following.
Code:
.OPTION CAPTAB
Adds up all the capacitances attached to a node and prints a table of singleplate
node capacitances.
Syntax
.OPTION CAPTAB
Default 0
Description
Use this option to print a compiled table of single-plate node capacitances for
diodes, BJTs, MOSFETs, JFETs, and passive capacitors at each operating
point.
Note:
When .OPTION CAPTAB is used to estimate the equivalent capacitance of
the circuit nodes, HSPICE can give a zero capacitance values for some
nodes when a resistance is connected to that node. The reason for getting
0 is that the capacitance is a dynamic, frequency-dependent capacitance
and not a static capacitance. You need to run an AC analysis to see a nonzero
node capacitance.
Cadence Spectre also have similar ability.

Last edited:

amr.maghraby

Junior Member level 2
Yes, it is.
can you please tell me how to find the parasitic capacitance in cadence IC 6.1.3

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I don't know what you want to mean by "in a schematic in cadence" at all.

However Synopsys HSPICE have following.
Code:
.OPTION CAPTAB
Adds up all the capacitances attached to a node and prints a table of singleplate
node capacitances.
Syntax
.OPTION CAPTAB
Default 0
Description
Use this option to print a compiled table of single-plate node capacitances for
diodes, BJTs, MOSFETs, JFETs, and passive capacitors at each operating
point.
Note:
When .OPTION CAPTAB is used to estimate the equivalent capacitance of
the circuit nodes, HSPICE can give a zero capacitance values for some
nodes when a resistance is connected to that node. The reason for getting
0 is that the capacitance is a dynamic, frequency-dependent capacitance
and not a static capacitance. You need to run an AC analysis to see a nonzero
node capacitance.
Cadence Spectre also have similar ability.
i have connected a circuit in cadence and i want to know the value of the parasitic capacitance at this node
my question is wither there is an analysis that could give me the value of the parasitic capacitance at this node?

dick_freebird

If you include adding minor schematic mods, then I prefer
to add a shunt pulsed current source, who can inject a
known small charge (large enough to be seen, small enough
to be small-signal-ish) and look at the node step voltage
right at the end of the pulse. Q=CV.

Any "on" elements will steal from step voltage and you may
want to apply a little work at determining what went to R
and what went to C.

amr.maghraby

amr.maghraby

points: 2

Dominik Przyborowski

What would you like to do?
1. Simulate capacitance at specific node?
2. Extract capacitance for all nodes?
3. Read parasitic capacitance from extracted view?
What views you have?
What tools you have?

ThisIsNotSam

Mandatory reminder that Cadence is a company. There is no tool called Cadence...

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