What is the output produced in the ADC?
An ADC is an electronic circuit whose digital output is proportional to its analog input. Effectively, it ‘measures’ the input voltage and gives a binary output number proportional to its size.
How does ADC reference voltage?
The ADC output is the ratio between the analog-signal voltage and the reference voltage. Any noise on the analog reference causes a change in the converted digital value. For example, with an analog reference of 3.3 V (VAREF = VDDA) and a 1 V signal input, the converted result is (1/3.3) × 4095 = 4D9h.
What is reference in ADC?
ADCs convert analog inputs that can vary from zero volts on up to a maximum voltage level that is called the reference voltage. The reference voltage determines the ceiling of what the ADC can convert, and is essentially the yardstick against which every proportion and result is measured.
Is the reference voltage External to the ADC?
The voltage reference is external to the ADC, and along with an amplifier to drive the reference, contributes to the overall system noise. For microcontrollers (MCUs) that have integrated (internal) ADCs, you may or may not have control over the reference voltage.
What are the units of the output of an ADC?
If the input signal is 1V, with a 3V reference, then the result (no matter what resolution you have, be it 8 bit or 24 bit) will be 1/3. The better resolution ADC obviously gives you much better ability to distinguish between 1.001V and 1.002V, or similar difference in input signals.
How are the results of an ADC obtained?
The results are obtained usually by a sample-and-hold input setup, which using a known conversion time, the resulting voltage built up on the sampling capacitor is the representation of the external signal input. The results are digitized as a proportion of a reference voltage given to the ADC.
What should the V ref be for an ADC?
The V REF for your ADC should be very stable regardless of the temperature it experiences. It should demonstrate excellent performance over temperature. In short, the lower the number of ppm/°C, the better. Additionally, the initial output voltage accuracy of VREF should be low, in the range of 0.5% or less for precision ADC applications.