ADC reference voltage converters

Analog to Digital Converters are devices that are used to convert analog values into discrete numbers as binary numbers which can be processed by a processor. Since almost all the natural physical parameters around us have analog values, ADCs are an integral part of many signal processing systems. Nowadays, advanced ADC Integrated Circuits are available, which makes the analog to digital conversion process quicker and more accurate.

Working of an Analog to Digital

The ADC records the value of the input analog signal with each clock pulse and allots it a proportional value. This value is then converted into binary numbers having a certain number of bits. These sets of binary numbers measured against time give us the desired digital output, which can be then passed to a microcontroller or a microprocessor.

ADC reference voltage

Every Analog to Digital Converter has a certain maximum voltage which can convert into digital. This is the voltage that will receive the highest value in the corresponding digital scale. This voltage is called the reference voltage for the ADC and is represented by VRef. All the discrete steps lie between this 0 and VRef and each discrete step has the value VRef /2n where n is the number of bits that are being used to represent individual values. So, 2n is the total number of allowed discrete values that the output from the ADC can attain. The greater the value of n, the greater will be the resolution of the ADC, which equal to the value of the smallest discrete step.

So, the resolution of an ADC depends on the adc reference voltage and the total number of possible discrete steps in the output range. For example, if we are using a reference voltage of 10 V with an 8-bit ADC, we will have the output on a scale of 0 to 255 (28 = 256). Also, the reference voltage divided by the number of possible discrete steps gives us the resolution (value of each step), we get the resolution to be 39 mV. So, the value of any given discrete step will be a whole number multiple of 39 mV.

The precision with an ADC carries out analog to digital conversion depends mainly on two parameters- the resolution and the sampling rate. The greater the number of samples an ADC takes in a given time interval, the closer the digital output comes to the analog input.