Vladislav D
Community Member
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Posts: 76
The Netherlands
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By "positive feedback comparator" I guess you imply a dynamic comparator which does not consume DC current? First of all, a latch always has a positive feedback. Placing an amplifier in front of the latch, makes the response faster with a small input signal since the regeneration time is a function of the input voltage at the latch input. Dynamic comparators have a latch as well.
Now, the meaning of the positive feedback is that, even with a very small voltage, it (positive feedback) starts the regeneration process until the output hits the rail. So, the minimum detectable signal is a function of time, and will be infinitely small if you wait infinitely long, assuming that there is no noise in the circuit. Moreover, comparator is a strongly non-linear device, what makes somewhat difficult to describe it's behavior mathematically.
I would recommend to start a study of dynamic comparators from the StrongArm comporator.
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