Voltage Controlled Switch OFF state resistance 01 PUBLIC

Note that it is not clearly documented but switches in CL do not have an infinite OFF state resistance. This can lead to unexpected results.

Note that it is not clearly documented but switches in CL do not have an infinite OFF state resistance. This can lead to unexpected results.

For example, a DC plot of this circuit:

https://www.circuitlab.com/circuit/586t3d/voltage-controlled-switch-off-state-resistance-01/

with R1 removed from the circuit would show V(output) = 1V.

Here's why.

The resistance to ground at the Output node is infinite because it is an open circuit.

However, the switches in CL are not ideal. They have a very large but finite OFF resistance.

Therefore when operating into an open circuit load there would be no difference between the ON and OFF state voltages at the Output node.

The example demonstrates this using a DC Sweep probing V(output) with a Decade Sweep of the value of R1 (R1.R) from 1e12 to 1e18 at 10 points/Decade.

It can be seen that V(Output) = 0.5V when R1.R is equal to around 1e15 Ohms.

This is the undocumented OFF state resistance of the CL voltage controlled switch.

Note that if a CL voltmeter were to be connected in place of R1 then there would be a clear ON/OFF state difference because the CL Voltmeter has a user definable finite resistance with a default value of 1G.