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SAMPLE AND HOLD versus TRACK AND HOLD

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henrywent

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track and hold

hi there,
what is the difference between SAMPLE AND HOLD and TRACK AND HOLD circuit?More often than not, people use TRACK AND HOLD circuit in their data convertors. But we hear SAMPLE AND HOLD more often in the literature. IS SAMPLE AND HOLD THE IDEAL MODEL FOR TRACK AND HOLD? please explain more, i am really confused.
regards,
henry
 

rfsystem

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track and hold sample and hold

The S/H is the idealized T/H

Every sample and hold circuit need some time to aquire the input signal. While this aquiring phase the output is typical tracking the input. If not there is a second energy storage element which buffer the signal. Depending on the design specification the tracking or aquisitation phase could perform as a good amplifier instead of accurate sampling the signal at the end of the aquisitation phase. Because all T/H are used for ADC's or discrete filter applications the stored signal is more important. Therefore signal specification is most defined for the stored signal.

The transistion form track to sample should be as sharp and jitterfree as possible. You can define the sampling process by an aparature function over time. This define the fraction of signal impact to the stored value. It is like a distribution function with a max shortly before the sampling switch closes.
 

    henrywent

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henrywent

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track sample and hold

thank you for your reply, is there any link or document dealing with this topic?
 

Petre Petrov

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