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Is it possible to precision rectify a 1MHz signal?

For an Overcurrent detector, the present solution is a full wave bridge of MBR0530 diodes, and the forward drop of these diodes is the cause of increasing error towards the low setting.

The current signal is presented across a 5.1 ohm resistor from a 1:1000 current transformer, rectified, and compared to an adjustable and metered reference, with an AD311 comparator.

There is a 5 volt and a 9 volt supply available, and the frequency of the signal can vary from 20kHz and up to 1 MHz.

Is it possible to build a precision rectifier that runs from a single supply, and functions up to 1 MHz?

Cheers, Finn Hammer

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  • It is always nice to be able to answer one's own questions, since it usually means, that the effort to find out has been succesful.
    I tried to build the circuit mentioned in this publication:

    http://www.analog.com/library/analogDialogue/archives/44-04/absolute.pdf 

    but instead of the AD8277 I used AD8028 and 2.2k resistors instead of 40k, I got this result at 500kHz, which is sort of ok, I think

    At higher frequencies, the inverted part of the signal gets more ragged, and obtains a peak at the leading edge, This peak exeeds the absolute value around 800kHz, and this is exactly within speck, so I will stick with this solution.

    Cheers, Finn Hammer

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  • It is always nice to be able to answer one's own questions, since it usually means, that the effort to find out has been succesful.
    I tried to build the circuit mentioned in this publication:

    http://www.analog.com/library/analogDialogue/archives/44-04/absolute.pdf 

    but instead of the AD8277 I used AD8028 and 2.2k resistors instead of 40k, I got this result at 500kHz, which is sort of ok, I think

    At higher frequencies, the inverted part of the signal gets more ragged, and obtains a peak at the leading edge, This peak exeeds the absolute value around 800kHz, and this is exactly within speck, so I will stick with this solution.

    Cheers, Finn Hammer

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