question about reference circuit

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Lantis

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For a flash AD (pipeline AD), I need a reference voltage 1.25V and 1.75V which

is connected to sample/Hold circuit (comparator).

Because of the clock feedthrough and charge injection of the sampling switch, the

reference voltage is changed. So I add a buffer connected opamp to isolate it.

The buffer input is i.25 and 1.75(volt).

I wandered that increase the opamp bandwidth and slew rate would help the

settling behavior of the buffered output voltage.

Could any body help me plz?
 

As far as I know, the comparator offset voltage caused by the charge injection or others can be igonored if it is not too large for there is digital correction logic can correct it later.
 

Maybe you can use external voltage reference for high speed flash ADC.

It use large external capacitance to fix the reference voltage and it is very useful.

Yibin.
 

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