App note: Enhancing ADC resolution by oversampling

Posted on Sunday, January 1st, 2012 in app notes by Arup
Oversampling in AVR

Better ADC resolution can be accomplished by oversampling two or more ADC readings and then averaging them. If you’re not satisfied with a microcontroller’s 10 bit ADC and need more resolution, check out this application note from Atmel.

Increasing the ADC resolution by one bit requires 4 ADC measurements.  Four 10 bit readings are needed for one 11 bit reading. Similarly, the maximum bandwidth is reduced. If you go from 10 bit to 16 bit, the maximum bandwidth comes to 7600 Hz divided by 46 (i.e, 4096) – that’s only ~2 Hz.

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One Response to “App note: Enhancing ADC resolution by oversampling”

  1. rsdio says:

    This technique only works when the input is DC, such that the value does not change during the multiple samples. Alternatively, the input can be filtered with a low-pass to limit the bandwidth to the smaller effective sample rate, thus keeping the value from changing too much between each sample that contributes to the average.

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