Synchronous rectifier

Hi, I am working on a integrated synchronous rectifier, in which a
comparator sense the Vds of a MOSFET to control the turning on and off
of the MOSFET. So the comparator is a zero-crossing detector. In the
design of the comparator, the offset is well controled to enhance the
efficiency. But in very light load/zero load, there is some
oscillation. Thus my question is: is anyone of you once meet this
instability problem and could anyone give some advice on this?

Thanks...
Eric

.

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