I saw some sample and hold circuits from the Internet,and i find there will be a buffer in the output,so i want to ask what does that buffer do for the sample and hold,can i use two stage amplifier as that buffer?

enter image description here

The two stage amp schematic


     Mostly the output buffer presents a really high impedance to the storage capacitor so it does not discharge significantly into the next stage.

  • \$\begingroup\$ Then why don't we just add a high resistance instead of the output buffer? \$\endgroup\$
    – Shine Sun
    Nov 2 '17 at 5:06
  • \$\begingroup\$ @ShineSun if you just added a high resistance it would act as a voltage divider with the input impedance of whatever comes next and you would have a different voltage at the input. \$\endgroup\$
    – Trevor_G
    Nov 2 '17 at 11:37
  • \$\begingroup\$ Thankyou!@Trevor \$\endgroup\$
    – Shine Sun
    Nov 2 '17 at 12:59
  • \$\begingroup\$ Do you think can the two-stage amp act as a output buffer? \$\endgroup\$
    – Shine Sun
    Nov 2 '17 at 13:00
  • \$\begingroup\$ @ShineSun "two stage amp" is meaningless without a drawing or schematic. It could mean a zillion things. \$\endgroup\$
    – Trevor_G
    Nov 2 '17 at 13:18

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