Hi everyone,
I have design input protection for a CAT4 voltmeter. The Voltmeter need to measure AC+DC simultaneously.
The input impedance is 10M ohm.
At the moment i have an mov and a PTC as input protection that clamps at 2kv.
I need some sort high speed voltage clamp either at the input of the buffer (2.5Vpk) or further up the voltage divider (flexible).
As the input impedance it at 10Mohm, the bias current seems to be an big issue as it skews the voltage value.
I have found a BJT circuit that has low leakage and is high speed but i cant seem to find any analysis on the design. (attached)
I have also heard there can be some sort of fet circuit that also has ultra low leakage
I'm open to any suggestions :)
thanks in advance
