How to select ADC resolution?

How to select ADC resolution?

How Much ADC Resolution Do You Really Need?

1. Determine the full-scale input voltage range of the data logger (from the amplifier’s input, if one is used); we’ll call this VD.
2. Determine the full-scale output voltage range of the signal you want to measure; we’ll call this VS.

How to measure ADC noise?

To measure the amount of input-referred noise, the input of the ADC is either grounded or connected to a heavily decoupled voltage source, and a large number of output samples are collected and plotted as a histogram (referred to as a grounded-input histogram if the input is nominally at zero volts).

How to measure enob of ADC?

ENOB is based on the equation for an ideal ADC’s SNR: SNR = 6.02 × N + 1.76 dB, where N is the ADC’s resolution. A real world ADC never achieves this SNR due to its own noise and errors. You can rearrange the equation to calculate an ADC’s effective N, or ENOB as we commonly call it: ENOB = (SNR – 1.76)/6.02 dB.

What is the effective resolution of an ADC?

Using the sameADC with a PGA setting of one, the noise rises to 1.53 μVrms. With an input range of 5V (±2.5V/1), the effectiveresolution becomes 21.6 bits. The best practice is to checkthe ADC’s data sheet for the input range that you need. Noise-free resolution uses the peak-to-peak-voltage noiserather than the rms noise.

What kind of noise does an ADC have?

All ADCshave a certain amount of noise, including both input-referrednoise, which is inherent to the ADC, and quantization noise,which is the noise that occurs while the ADC is converting.Specifications such as noise, ENOB (effective number ofbits), effective resolution, and noise-free resolution in largepart define how accurate an ADC is.

How is quantization noise related to the ADC?

quantization “noise” actually appears as an offset error in the ADC output. Finally, an obvious but important result of quantization noise is that the ADC cannot measure beyond its resolution, as it cannot distinguish between sub-LSB changes in the input. Unlike quantization noise, which is a byproduct of the

Where does the output of an ADC come from?

The output of most high speed or high resolution ADCs is a distribution of codes, typically centered around the nominal value of the dc input (see Figure 2).