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AMC1336: Max input frequency of AMC1336, AMC1303 and AMC1306

Hirotaka Matsumoto
Guru 27585 points
Part Number: AMC1336

Hi all

Would you

How much is the maximum input frequency of AMC1336, AMC1303 and AMC1306?
The mesurment is the current or voltage, therefore we assume that 1MHz is enough to measure. 

Kind regards

Hirotaka Matsumoto

  • 0
    TI__Guru**** 181021 points

    Hi Matsumoto-san!

    Can you please expand a little on what you mean by the maximum input frequency to the AMC1336, AMC1303 and AMC1306?  Are you referring to the highest frequency input that the devices can reliably sample?  If so, I would have to say that it depends on the applied OSR used in whatever digital filter you apply to the output data stream of the device.  With the AMC1336 for example, if you were to use an OSR of 256 and a modulator clock of 21 MHz, you could achieve a data rate of 82 kSPS.  By Nyquist then, you could in theory resolve a signal of 41 kHz.  The AMC1303M25, could get you a sample rate of 78 kSPS with an OSR of 256.  Do let us know what you are trying to accomplish and we'll help as best we can!

  • 0
    TI__Guru 55332 points

    Hi Matsumoto-san,

    Thank you for your question. 

    The maximum input frequency of the device is limited by the sampling frequency of the modulator, which for modulators with externally supplied clocks is in the range of 9-21MHz. Nyquist theory will apply here and is the limiting factor. You want to sample at least 2x the input frequency so that you do not have measurements with an un-resolvable frequency. If the input frequency is high, then the clock frequency should high be as well. Sampling at 1MHz is possible but will come at the expense of resolution.

    Please see this paper for additional information: http://www.ti.com/lit/wp/sbaa359a/sbaa359a.pdf

  • 0 in reply to Tom Hendrick
    Guru 27585 points

    Tom san

    Thank you so your reply!
    OK, we got it.
    We would like to confirm that it depends on sampling frequency.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Guru 55332 points

    Hi Matsumoto-san,

    Here is a simple block diagram to help illustrate the signal chain.

    Input signal -> modulator -> digital filter -> output result

    It depends on both the sampling frequency of the modulator and the digital filter. There is a limitation to the maximum input frequency that the modulator can resolve which is what my post covered. However as Tom pointed out, the digital filter is what will ultimately limit the maximum frequency input signal that can be sampled. Digital filters are highly configurable and change depending on the resolution/maximum input frequency requirements of the system. The paper I linked goes into this in more detail.