Getting/Setting Calibration Coefficients - 2.6 English

Zynq UltraScale+ RFSoC RF Data Converter v2.6 Gen 1/2/3/DFE LogiCORE IP Product Guide (PG269)

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2.6 English

As well as automatic calibration, all four calibration blocks (OCB1, OCB2, GCB, TSCB) are available for getting and setting user coefficients. The application reads back the coefficients generated when calibration is un-frozen, and restores them when needed; this helps to maintain the RF-ADC performance when the input signal does not meet calibration requirements. Note that both the OCB1 and OCB2 blocks are independent to input signal amplitude; these two OCB blocks are not recommended for coefficients updating manually. This feature is available for each RF-ADC in the IP wizard. Enabling this feature increases the size of the IP.

Restoring calibration coefficients with the XRFdc_SetCalCoefficients API disables the real-time calibration automatically. The XRFdc_DisableCoefficientsOverride API is provided to disable this user coefficients override mode and re-enable the real-time calibration. The real time port Calibration Freeze has no effect when the real time calibration is disabled. The loaded coefficients for OCB1/2 and GCB do not seed calibration; this can cause temporary spurs when re-enabling the calibration with the XRFdc_DisableCoefficientsOverride API as the calibration algorithm needs to converge again.

Note: The following are two limitations that apply for Gen 1 and Gen 2 devices.
  1. The user coefficients getting/setting for GCB is only valid when the DDC channel is in 1x (bypass), NCO off mode, and the samples per AXI4-Stream must be four samples for the Quad RF-ADC and eight samples for the Dual RF-ADC
  2. The calibration block OCB1 does not support calibration coefficients get/set.