Is there a way to measure the equivalent capacitance from a node to ground in a circuit?

I suspect you must have picked the detail=nodetoground option rather than the default "node" or the other alternative "nodetonode" option. If you pick "nodetoground" it only includes the capacitance to ground, not the effective capacitance to ground. 

With this netlist:

// Example of various captab detail options

VDD (vdd 0) vsource dc=1.8
C1 (a vdd) capacitor c=1p
C2 (a 0) capacitor c=1p

dc dc
captabDefault info what=captab where=screen
captabNodeToNode info what=captab where=screen detail=nodetonode
captabNodeToGnd info what=captab where=screen detail=nodetoground

Then I get this in the output (note I only posted the relevant part):

**********************************
Capacitance Table `captabDefault':
**********************************
Capacitance values computed in DC analysis `dc' at T = 27 C.

a : a fixed=2 p , variable=0 , sum=2 p .

vdd : vdd fixed=1 p , variable=0 , sum=1 p .

*************************************
Capacitance Table `captabNodeToNode':
*************************************
Capacitance values computed in DC analysis `dc' at T = 27 C.

a : a fixed=2 p , variable=0 , sum=2 p .
a : 0 fixed=1 p , variable=0 , sum=1 p .
a : vdd fixed=1 p , variable=0 , sum=1 p .

vdd : vdd fixed=1 p , variable=0 , sum=1 p .
vdd : 0 fixed=0 , variable=0 , sum=0 .
vdd : a fixed=1 p , variable=0 , sum=1 p .

************************************
Capacitance Table `captabNodeToGnd':
************************************
Capacitance values computed in DC analysis `dc' at T = 27 C.

a : 0 fixed=1 p , variable=0 , sum=1 p .

vdd : 0 fixed=0 , variable=0 , sum=0 .

As you can see from the lines I highlighted in red, you are getting with the a:a lines the total capacitance on a node.

BTW, the attach image problem for me seems to be broken in Safari currently but OK in Firefox. I'll speak with our IT folks who manage the forums to see if it can be addressed (it's happened before and normally needs something resetting I think).

Regards,

Andrew.

I suspect you must have picked the detail=nodetoground option rather than the default "node" or the other alternative "nodetonode" option. If you pick "nodetoground" it only includes the capacitance to ground, not the effective capacitance to ground. 

With this netlist:

// Example of various captab detail options

VDD (vdd 0) vsource dc=1.8
C1 (a vdd) capacitor c=1p
C2 (a 0) capacitor c=1p

dc dc
captabDefault info what=captab where=screen
captabNodeToNode info what=captab where=screen detail=nodetonode
captabNodeToGnd info what=captab where=screen detail=nodetoground

Then I get this in the output (note I only posted the relevant part):

**********************************
Capacitance Table `captabDefault':
**********************************
Capacitance values computed in DC analysis `dc' at T = 27 C.

a : a fixed=2 p , variable=0 , sum=2 p .

vdd : vdd fixed=1 p , variable=0 , sum=1 p .

*************************************
Capacitance Table `captabNodeToNode':
*************************************
Capacitance values computed in DC analysis `dc' at T = 27 C.

a : a fixed=2 p , variable=0 , sum=2 p .
a : 0 fixed=1 p , variable=0 , sum=1 p .
a : vdd fixed=1 p , variable=0 , sum=1 p .

vdd : vdd fixed=1 p , variable=0 , sum=1 p .
vdd : 0 fixed=0 , variable=0 , sum=0 .
vdd : a fixed=1 p , variable=0 , sum=1 p .

************************************
Capacitance Table `captabNodeToGnd':
************************************
Capacitance values computed in DC analysis `dc' at T = 27 C.

a : 0 fixed=1 p , variable=0 , sum=1 p .

vdd : 0 fixed=0 , variable=0 , sum=0 .

As you can see from the lines I highlighted in red, you are getting with the a:a lines the total capacitance on a node.

BTW, the attach image problem for me seems to be broken in Safari currently but OK in Firefox. I'll speak with our IT folks who manage the forums to see if it can be addressed (it's happened before and normally needs something resetting I think).

Regards,

Andrew.