analog DC voltage register

[huihuicn]

Hi, every one:
Who knows what kind of circuit can realize the function of analog DC voltage register, which can store different level of voltage for next processing.
Thanks!

 

[chuckey]

Its called a sample and hold. The cheapest way is to charge a capacitor via a diode, if the load resistance is extremely high the voltage will remain on the capacitor for some time (but not days!). There are specialized ICs for this purpose - use Google.
Frank

 

[keith1200rs]

I would suggest an analog switch and capacitor for a sample and hold, not a diode. Also it is usual to buffer the capacitor voltage with a FET or CMOS opamp.

Keith

 

[crutschow]

How fast do you need to acquire the voltage and how long do you need it to be stable?

 

[huihuicn]

The speed is about 125ns ~150ns, and I would to remain the voltage for about 15us.

 

[KerimF]

Knowing an estimated value of the source impedance (resistance) and of the one that loads the sample and hold circuit helps in completing the design.

 

[huihuicn]

Thanks for your reply! I will have a try

 

[crutschow]

An IC such as this should do what you want. However those are not cheap since acquiring a signal at such a high speed requires state-of-the-art ICs.