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Design >> Analog Design >> Adding two voltage in a capacitor array!
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Message started by jockeymonto on Jan 1^st, 2014, 11:20pm

Title: Adding two voltage in a capacitor array!
Post by jockeymonto on Jan 1^st, 2014, 11:20pm

Hi all,

I have an array of two capacitors and I want to add two voltages thru them. Please see my attached figure. All the boxes in the figure are switches. I have numbered all nodes to their respective voltages!

1. 1 is the input of the switch which when high shorts 200mV on the node 10.Now we have 200mV at the upper plates of the capacitors for 2us and then the node is left floating.
2. Now node 2 and 5 short the lower plates of both capacitors to ground.
3. Then node 3 shorts node 8 (lower plate of 1st cap) to 0.6V from 5 to 9us. Then after 10us node 4 connects node 8 to ground. Now the charge from node 8 should give rise to equal but opposite charge at node 10 and the net voltage there should be 0.2-0.6=0.4V. But why node 10 is not this voltage. its around 0.75V. Is it because it is floating?
Why is node 9 connected to 0.6V when it is actually floating.
4. Now node 9 is shorted to 0.2V for 4us and then shorted back to ground. The charge at node 9 must create and equal and opposite charge at node 10 and by now the net charge at node 10 should be 0.2-0.6-0.2 but it is something else.

How can I add the two voltage 0.2 and 0.6 successfully?