Will i need amplifier in this case?

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Discussion Overview

The discussion revolves around the use of a 12-bit ADC (analog to digital converter) with a specific input range of +50mV to -50mV for measuring a signal with a peak-to-peak voltage ranging from 0.7mV to 1mV. Participants are exploring whether an amplifier is necessary to achieve adequate resolution for the measurements.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that using the ADC directly may not provide sufficient resolution due to the limited number of readings available within the specified voltage range.
  • Others argue that the ADC could be used directly, but emphasize the need for an amplifier if higher resolution is required.
  • One participant mentions that the resolution needed depends on the specific measurements being taken, indicating that sometimes fewer readings may suffice.
  • Concerns about input noise affecting the ADC's performance are raised, with a recommendation to use an amplifier with a gain of 50 for better results.
  • Another participant clarifies the signal characteristics, stating that the signal has a peak-to-peak voltage of 700uV and a range from -500uV to 500uV, which may affect the measurement strategy.

Areas of Agreement / Disagreement

Participants express differing views on whether an amplifier is necessary, with some advocating for its use due to resolution concerns and others suggesting that the ADC could suffice under certain conditions. The discussion remains unresolved regarding the necessity of an amplifier.

Contextual Notes

Limitations include the dependence on the specific measurement requirements and the potential impact of input noise on the ADC's performance. There is also uncertainty regarding the precise resolution needed for the measurements.

samaaa
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Hi:

i have ADC(analog to digital) has a resolution 12 bits
and the input range is from +50mV to -50mV,
this men the precision is about 24uV

i want to use this ADC for a signal has Vp.p from 0.7mV to 1mV

so
can i use this ADC directly?or i must use amplifier ??
 
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You could just use the ADC but the problem is you only have 12 readings in that voltage range. If you need more resolution than that you need an amplifier.
 
Floid said:
You could just use the ADC but the problem is you only have 12 readings in that voltage range. If you need more resolution than that you need an amplifier.
no, i have 29 readings (from 700uV/24uV) .

Floid said:
If you need more resolution than that you need an amplifier.

how can i know what is the resolution i must use??
is there any equation to determine the resolution?
 
samaaa said:
no, i have 29 readings (from 700uV/24uV) .



how can i know what is the resolution i must use??
is there any equation to determine the resolution?

The resolution you need depends on what you are trying to measure, in some cases two values might be enough!

However, remember that the input noise of your ADC is also an issue, so in real life you will always need an amplifier.
Just get/build an amplifer with a gain of 50.
 
no, i have 29 readings (from 700uV/24uV) .

If you have a signal that you know ranges from 0.7mv to 1mv I would think that when measuring it your interest would be in the 300uV difference between the two.
 
Floid said:
If you have a signal that you know ranges from 0.7mv to 1mv I would think that when measuring it your interest would be in the 300uV difference between the two.

you don't understand me, the signal has Vp.p=700uV or 1 Vp.p(ECG signal)
the range may be from - 500uV to 500uV
 

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