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Altera_Forum
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16 years ago

Appropriate ADC for educational project?

Hello folks! I'm a student of 'Network Systems and Data Communications' department in Greece and am doing my final project/dissertation right now in Leiria, Portugal at Electrical Engineering d...
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Altera_Forum
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16 years ago

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Also, I didn't exactly understand the role of decimation of the delta-sigma?!

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ADS1202 is special in so far as it's only a SD modulator rather than a complete SD ADC. The latter would include the decimation function and output parallel data at the specified rate. The ADS1202 sends a bit bit stream at the SD oversampling frequency and needs external decimation to work as a full-featured ADC. The main reason, why the ADS1202 has been designed this way is because it's intended for operation through a isolated serial interface. But it's also a versatile building block for a FPGA analog front end.

You should refer to the basic SD converter theory, if you are interested to learn more about the role of decimation in SD operation, particularly noise shaping. But I think, the ADS1202 applications give some insights. A sinc^x filter (CIC decimator is just another word for it) hasn't a steep characteristic. If you decimate voice data to a moderate sampling frequency (e.g. 8 to 16 kHz) with this filter, high frequent signal components would be attenuated considerably, you may want to add either a correction filter or use a decimator with different characteristic in the final step of a multi stage decimator design.