AD6676 FAQ: Can you explain what the “Profile feature” is and why I it may be advantageous to use in some applications?

Document created by rdowning on Nov 25, 2014
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This feature can be useful for applications that may desire to cover a larger IF bandwidth range but do not necessarily need the instantaneous bandwidth.  By dividing the larger IF bandwidth into  narrower “sub-bands” , it is possible to increase the Σ-Δ ADC’s dynamic range for each “sub-band” versus one Σ-Δ ADC setting that tries to cover the entire IF bandwidth.  Recall that the dynamic range of a Σ-Δ ADC is a strong function of its oversampling ratio (i.e.  OSR= FADC/(2*BW)).


This feature allows the Σ-Δ ADC to store up to four different profile settings that can be quickly recalled within 1 µs via a SPI command without recalibrating the Σ-Δ ADC. Calibration of each of the different profiles occurs during the device initialization phase with each profile consisting of the following different application parameters: BW, FIF, IDAC1FS, and MRGN.   To ensure that the JESD204B link is maintained when switching between profile settings, the FADC setting along with the decimation filter and JESD204B settings must remains common.

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Figure91. NSD Performance with Narrow-Band Profiles (FIF = 220 MHz, 260 MHz, and 300 MHz, BW = 120 MHz, FADC = 3.2 GHz, LEXT = 27 nH)


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