Voltage Comparator Circuit Needed LM311 Equivalent

Wow Roff. That's a really nice schematic you put up. I'm actually doing the same ADC project as AMD, but with my setup, I'm most likely going to be pulling 702khz into the comparator so that I only have a maximum error % of 1%. Would your circuit still be able to handle that?

bawobogo said:

Wow Roff. That's a really nice schematic you put up. I'm actually doing the same ADC project as AMD, but with my setup, I'm most likely going to be pulling 702khz into the comparator so that I only have a maximum error % of 1%. Would your circuit still be able to handle that?

Click to expand...

1% of what?

Papabravo said:

by your leave.

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define: "by your leave" - Google Search

?

Roff said:

1% of what?

Click to expand...

1% error in the output voltage level vs in the actual input voltage level.

The nyquist freq is 2x's the maximum input freq but can cause a large error in the output voltage level vs input voltage.

I used the formula

%error = (1-(R/sqrt(1+R^2))*100

where R = ratio of the ADC bandwidth vs the input frequency

I solved for R and got R=7.02 ish and so the ADC bandwidth would have to be 702 khz.

I got the formulas and stuff off of Bandwidth, Sample Rate, and Nyquist Theorem - Developer Zone - National Instruments.

If I did something wrong, please correct me. I honestly hate analog and much prefer digital logic, fpga, etc.

Thanks in advance for your help.

What are you going to do with this A/D? What is the input signal source? What is the sample rate?