Hi,
I have a general question about a system I am working on. In the project that I am working on, we have a sensor which needs to be excited externally with an AC signal (a sinusoidal). For this purpose, I am planning to use a DAC with a buffer. After excitation, the sensor output needs to be sampled to be processed further. As far as I learned, the noise level at the input of the ADC will be a combination of ADC input referred noise (combination of reference noise, thermal noise and quantization noise), ADC input driver amplifier's noise and the sensor noise. And the sensor noise will be a combination of the sensor's inherent noise and DAC's noise(output driver's noise, DAC quantization noise). In such a closed loop system I am aiming to select the ADC to meet the overall performance criteria (sensitivity etc). After that, while selecting the DAC+Buffer, I am aiming to get an overall rms noise which is equal to one tenth that of ADC input referred noise(Or a DAC+Buffer whose SNR is 10dB higher than ADC's SNR). SO when selecting the ADC and DAC, I assume that I need to select a (N+2) bit DAC and N bit ADC.
Is my approach and resulting selection criteria reasonable? Do you have a better approach? After making sure of this approach I will continue component selection process.
Best regards
Mustafa
