Can frequency affect conversion time in a system?

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Increasing the frequency in a system is generally believed to reduce conversion time, as higher sampling rates can lead to quicker data processing. The discussion revolves around a circuit that functions as a digital-to-analog converter, where a counter processes clock pulses to generate binary outputs. The op-amp acts as a comparator, determining when the counter should stop based on the relationship between the analog input signal (Va) and the counter's output (Vx). The circuit's operation hinges on the AND gate allowing signals to pass only when both inputs are active, facilitating the counting process. Ultimately, the system's functionality is dependent on the precise interaction between these components, particularly when Vx equals Va, which halts the counting until a reset occurs.
  • #31
Yep.
 
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  • #32
But how can I find the resolution based on Va?

My idea was that Va max defines our Vref, but if Vref isn't defined to us we can't tell the resolution and thus can't solve for Va if given a digital output
 
  • #33
What is Vref?
I don't see it in your problem statement.
Or did you mean Vx?
 
  • #34
Doesn't every D/A has a Vref? How can it function without a analogue input?
 
  • #35
Femme_physics said:
Doesn't every D/A has a Vref? How can it function without a analogue input?

I'm getting confused here.

In your problem statement there is no Vref.

And yes, a DAC would typically have a Vref connected.
Should I assume you mean the voltage that the maximum digital input maps to?

Either way, such a Vref is not really an input, since it is fixed and usually not shown.
 
  • #36
I like Serena said:
I'm getting confused here.

In your problem statement there is no Vref.

And yes, a DAC would typically have a Vref connected.
Should I assume you mean the voltage that the maximum digital input maps to?

Either way, such a Vref is not really an input, since it is fixed and usually not shown.

So to find the resolution of the converter I just use Va Max?
 
  • #37
Femme_physics said:
So to find the resolution of the converter I just use Va Max?

I'm still confused.

Which resolution?
What would Va Max be?
 
  • #38
Suppose Va max is 5. The binary output of the converter in question (the one at the original message) is 01001101. I am asked to find Va in that case. You're asking me "what resolution", but You can't solve it without one because you have the formula Va = Resolution x Output in base 10


Hmm... Do you follow me?
 
  • #39
I'm asked to calculate Va, if the counter output is (01101110)2
In the absence of a specified Vx max (or Va max) you could express your answer in terms of "Vx max", the maximum analog output available from the DAC.

So, if 11111111 → Vx max,
then 01101110 → k⋅Vx max
Find k.

You should be able to express resolution in terms of Vx max

I'm not sure how punctilious one should be in answering this question. But for the comparator to stop the action, Vx necessarily must always be able to exceed Va, so this implies Va max < Vx max
 
  • #40
Femme_physics said:
Suppose Va max is 5. The binary output of the converter in question (the one at the original message) is 01001101. I am asked to find Va in that case. You're asking me "what resolution", but You can't solve it without one because you have the formula Va = Resolution x Output in base 10Hmm... Do you follow me?

Do you have a problem statement?

To find the Va that corresponds to (01001101)2 you would need the maximum Vx output your DAC can give.
 
  • #41
Hi ILS, NasO, I'll clarify the question...


"The following is a main scheme of an A/D converter with 12 bits. Max Va is 5 [V].

In the A/D converter's output, the binary digit 010111110110 was measured. Calculate, what's Vin that was converted to this binary. "

Answer:

IMO I just do this


http://img834.imageshack.us/img834/1905/vinconversion.jpg

Whereas in the formula for resolution

Res = Vmax - Vmin / 2n = 5 / 212 = 0.0012207

Therefor I consider Va max = the Vmax of the converter and use this resolution to reach the answer.
 
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  • #42
Looks right to me!
 
  • #43
Thanks NasO2 :)
 

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