# Will i need amplifier in this case?

1. Nov 22, 2012

### samaaa

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 ??

2. Nov 22, 2012

### Floid

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.

3. Nov 23, 2012

### samaaa

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?

4. Nov 23, 2012

### f95toli

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.

5. Nov 23, 2012

### Floid

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.

6. Nov 23, 2012

### samaaa

you dont understand me, the signal has Vp.p=700uV or 1 Vp.p(ECG signal)
the range may be from - 500uV to 500uV