Bridge Rectifier Circuit Testing

[toldo83]

bridge rectifier circuit

I am testing 8 different rectifier topologies.
I saw something weird while testing a PMOS bridge rectifier. When no input voltage/current is applied to the rectifier, I read almost 1V at the output of the rectifier. I am wondering where this 1V is coming from. With NMOS bridge rectifier, in the same condition I get 0V at the output.

 

[frankvh]

rectifier circuit

Virtually every rectifier circuit has a capacitor on its output. Chances are, you're seeing a small residual charge on that cap, left over from the last time you switched the circuit on.

A digital multimeter is more prone to show this charge due to its high input impedance. An analog meter may not show it.

If it's a problem for you, you can (carefully) discharge the cap by using something like a 10 ohm resistor.

 

[FvM]

bridge rectifier circuits

I think, there's some information missing from original post, that could explain the mysterious observation. It didn't tell of large caps holding residual charges. It can be, of course. But as the sketched "circuit" lacks all necessary information, I don't see a reason to start guessing.

 

[toldo83]

testing rectifier

Tell me what information you need in order to help me. The capacitors size are 5pF. Technology used is UMC 0.18um. Whatelse?