SBAA525A september   2021  – may 2023 AFE7900 , AFE7920 , AFE7950

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Highlighted Products
    2. 1.2 Device Loopback Modes
      1. 1.2.1 ADC to DAC JESD Loopback
      2. 1.2.2 ADC to DAC Low Latency Loopback
  5. 2Tests and Results
    1. 2.1 Test Methodology
      1. 2.1.1 Hardware Setup
        1. 2.1.1.1 ADC to DAC JESD Loopback
        2. 2.1.1.2 ADC to DAC Low Latency Loopback
      2. 2.1.2 GUI Setup
        1. 2.1.2.1 ADC to DAC JESD Loopback
        2. 2.1.2.2 ADC to DAC Low Latency Loopback
      3. 2.1.3 Test Conditions
      4. 2.1.4 Test Results
        1. 2.1.4.1 ADC to DAC JESD Loopback
          1. 2.1.4.1.1 JESD 122.88 MSPS
          2. 2.1.4.1.2 JESD 184.32 MSPS
          3. 2.1.4.1.3 JESD 245.76 MSPS
          4. 2.1.4.1.4 JESD 368.64 MSPS
          5. 2.1.4.1.5 JESD 491.52 MSPS
        2. 2.1.4.2 ADC to DAC Low Latency Loopback
  6. 3Conclusion
  7. 4References
  8. 5Revision History

1.2.2 ADC to DAC Low Latency Loopback

AFE79xx also supports internal analog loopback as shown in Figure 1-2 without need of internal JESD interface. The fast loopback has been tested by driving RX Feedback channel using vector network analyzer for gain and group delay having 12-GSPS DAC output connected with internal NCO for lowest latency in signal bandwidth. Internal dithering is disabled in this mode. The bandwidth is measured across signal tone of 3.4 GHz to demonstrate loopback function for 5G n78 band. The device can also configure for different frequency band by tuning external matching circuit accordingly.

GUID-20210805-CA0I-LHJD-MTRG-5BLGPL1FDPBK-low.svg Figure 1-2 ADC to DAC Low Latency Loopback