Have you ever wondered how to improve the resolution of analog readings of your Arduino board? If yes, this is for you.
John Beale, discussing on the Dangerous Prototypes’ forum, quickly describes how to connect a Linear’s LTC2440 ADC to an Arduino board, which will provide you with an amazing 24 bit resolution.
The ADC, which is available in a SSOP package, can be connected to the Arduino via the SPI bus. Here John provides a brief sketch and some very useful comments to make it working properly.
For more detail: Arduino and the LTC2440 24bit ADC
French 
English