Could you be more specific?
You haven't said where you are measuring this signal.
I would not use a 9V battery like that as it will very soon drain, you will get no more than a few hours from it.
If you are trying to build a DAC with some sort of custom weighting
QuoteIf you are trying to build a DAC with some sort of custom weighting Yes, that's correct.This a project about an alternative design of a "DAC ".The circuit is incomplete and the weighted resistors value is WRONG (I need to calculate the right value yet ).I posted the schematic, only to explain the kind of topology of the net.Anyway, the problem is the signal for arduino, or maybe the probe of the scope.I am sure about this.Thanks.Giorgio.
When you mention the "problem", are you saying that you already have an end result that shows the effects of the overshoot of the square wave or that you are just predicting that the overshoot will affect your end result?
Maybe there is something wrong in my probe.
Take 5 resistors: tie your four output pins together through 4 reistors, R0..3, and from there tie them to ground through Rg. Buffer the output from where the resistors meet, with a jfet or an opamp.The output voltage is = (V0/R0 + V1 / R1 + V2 / R2 + V3 / R3) / (1 / R0 + 1/R1 + 1 / R2 + 1 / R3 + 1 / Rg). V0..3 is either 0 or 5v, representing the output from your mcu.
I only need to put the right capacitor at the right place
1) gate capacitance: as long as you have mosfets, you have gate capacitance, especially when they are undampened
Yes, I will put a dump resistor between the gate and the ground, to protect the mos.
I fall back on the old tried-and-true 4066 D/A switch.