Enhancing Analog to Digital Converter Resolution Using Oversampling Technique

Successive Approximation Register (SAR) type converters are used in PC plug-in data-acquisition boards or PC external data acquisition systems. They are by far the most popular ADCs in today measurement products. One reason for their popularity is their outstanding linearity which comes from the fact that they usually exploit a 1-bit quantizer. Even with a tri-level quantizer, linearity performance up to 20 bits has been reported. The oversampling is a method to improve the resolution of a converter, by software methods, with a little help from outside. It is useful when we have a microcontroller with SAR ADC and we want to measure output signals from a sensor with good resolution. The principle of oversampling is to take a great number of conversions, and calculate a mean value. It is useless to take lots of equal measurements and to calculate the mean value of them, because you will obtain the same result: the value. The whole idea is based on the presence of a white noise without a continuous component.