• What is the purpose of connecting capacitors to the gates in this bucket brigade device circuit? Why aren't they just connected to ground?
  • In every 2nd place there is a buffer transistor. How do these transistors prevent the voltage loss of the previous capacitors?

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    \$\begingroup\$ This certainly appears to be a homework or a test problem. Why don't you try to answer it yourself first? \$\endgroup\$ – jwh20 Jan 25 at 13:06
  • \$\begingroup\$ experimentalistsanonymous.com/diy/Datasheets/MN3007.pdf \$\endgroup\$ – Tony Stewart EE75 Jan 25 at 13:13
  • \$\begingroup\$ electrosmash.com/mn3007-bucket-brigade-devices \$\endgroup\$ – Tony Stewart EE75 Jan 25 at 13:16
  • \$\begingroup\$ @Tony Stewart Sunnyskyguy EE75 I've also found this datasheet and page about the circuit, but my problem is that, I can't fully understand why the capacitor are connected to the gate of the transistors, and only the first capacitor to ground. \$\endgroup\$ – gaborz Jan 25 at 13:46
  • \$\begingroup\$ If this is a homework question, then one starting point would be to think what other students may know that you don't, and where they may be looking for answers. Assuming that your professor is doing their job, think of what resources you should be using for the course: it is supposed to be an answerable question, after all. So that's 50% of the solution - just in the knowing that you're supposed to be able to figure it out. \$\endgroup\$ – Kuba hasn't forgotten Monica Jan 25 at 14:27
  • It isn't so much that the capacitors are connected to the gates per se, but that they're connected to the clock signals.

    The point is, the charge will flow from one capacitor to another only if the voltage on the first capacitor is higher. Only by raising the "bottom" of a capacitor to the highest system voltage during the high phase of its clock can you be sure of transferring all of its charge to the next capacitor.

  • The "buffer" transistors (the ones whose gates are connected to VGG) are actually there to make sure that charge transfers only in the forward direction, and that the capacitors never take on a negative voltage. Otherwise, the buckets would lose charge in both directions, and all you'd get out at the far end would be an average voltage for the whole chain.


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