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Hi, I have a question about quantization noise.

Yunsik Chung
Intellectual 1150 points

Hi, i was studying about delta-sigma modulator.

What i understood is that by increasing sampling rate dramatically we can distribute quantization noise across oversampling region.

So, by using digital filter and decimation after above process, we can achieve lower quantization noise in audio frequency region.

However, I cannot understand one thing.

We use 1-bit ADC in delta-sigma modulator. But, in the above picture, 'power in noise' is proportion to (delta)^2.

If we use 1-bit ADC, then delta would be extremely larger. So does not it increase the 'power in noise'?

Then, how can we say that 'total power in noise' is the same regardless of sampling frequency?

Thanks,

Yun

  • 0
    TI__Mastermind 24970 points

    Hello,

    Your  understanding of the digital filter and decimation are correct.

    A 1 bit ADC works differently and is actually completely depending on the sampling rate. I would suggest looking independently into the 1 bit ADC and its functionality.

    A 1 bit ADC can be thought of as a comparator that uses a reference point (usually the mid point) to make a measurement. If the reference point is wave shape, and the ADC is sampling at a substantially higher frequency than the reference signal, then you will be able to measure a higher resolution result.

    Regards

    Cynthia

  • 0 in reply to Cynthia
    TI__Intellectual 1150 points

    Hi Cynthia,

    Thank you for your reply.

    Could you explain in more detail why ADC is sampling at a substantially higher frequency than the reference signal if the reference point is wave shape?

    Thank,

    Best regards,

    Yun

  • 0 in reply to Yunsik Chung
    TI__Mastermind 24970 points

    Yun,

    A Single Bit ADC is really a whole topic to cover.

    Do you know what specific device the customer is using, and want issues they are having?

    Or is this to get a better understanding of the functionality? If so, I would suggest looking for educational material on the topic. I found one that might be right on the topic you are looking at: Performance Analysis for Channel Estimation With 1-Bit ADC and Unknown Quantization Threshold

    Regards

    Cynthia