SLVAF16A March   2021  – December 2021 AFE7920 , AFE7950 , TPS541620 , TPS62912 , TPS62913

 

  1.   Trademarks
  2. 1Introduction and System Description
    1. 1.1 Introduction
      1. 1.1.1 AFE79xx Noise and Ripple Requirements
      2. 1.1.2 TPS62913 Low-Noise and Low-Ripple Buck Converter
      3. 1.1.3 TPS541620 Dual 6A Converter
    2. 1.2 Block Diagram
    3. 1.3 Design Considerations
  3. 2Tests and Results
    1. 2.1 Test Methodology
    2. 2.2 Test Conditions
    3. 2.3 Test Results
  4. 3Schematic
  5. 4Conclusion
  6. 5References
  7. 6Revision History

2.3 Test Results

Performance tables and graphs comparing the original AFE7920 Original EVM with the TPS541620/TPS62913 modified board are shown below.

RX (Receive) SNR and SFDR

The FFT spectral plot is shown for an input frequency of 3.51 GHz, NCO of 3.5 GHz, and notch of 150. Figure 2-2 shows the performance of the standard EVM compared with the TPS541620/TPS62913 board. No close-in spurious on either board. The SNR and SFDR performance between the two units is roughly the same; however, the TPS541620/TPS62913 board achieves slightly better very close-in noise as shown in the spectrum close to the carrier as shown by the phase noise spread. The original board achieved -50dBFS, where the TPS541620/TPS62913 board achieved -62 dBFS, which shows improved performance with the new design.

Figure 2-2 Full Spectrum Comparison Plot
Figure 2-3 4 MHz Close-in Comparison Plot

TX (Transmit) Spectrum

Figure 2-4 show the transmit spectrum performance close to the carrier at 2 MHz span between the standard EVM compared with the TPS62913. Both boards show good performance, although the original AFE7920 board shows a spur at ~613kHz, likely from the original switching power supply. The TPS541620/TPS62913 low noise board has a clean spectrum and an increased switching frequency of 1 MHz.

GUID-20210118-CA0I-SQMM-8HLV-PKN5NS2CWWGP-low.gifFigure 2-4 2 MHz Span TX Spectral Plot
Table 2-1 Power Consumption Comparison for the 1.8 V rails on the Original and TPS62913 Boards
Configuration Input Voltage and Current Input Power
Input Power for the 1.8 V rails with the Original AFE7920 EVM with DC-DC converters + LDOs 5.6 V @ 1.165 A 6.526 W
Input Power for the 1.8 V rails with two TPS62913 5.6 V @ 0.944 A 5.286 W
Input Current and Power Savings for the 1.8 V rails 221 mA input current reduction 1.24 W Power Savings

The following are thermal images of the power supplies running when taking data for the power performance comparison tables.

Note:

Original Board DC-DC Max Temp is 47.9 C

Figure 2-5 Original 2.2V Switching Converter
Note:

Original Board LDO Max Temp is 57.7 C

Figure 2-6 Original 1.8V LDO
Note:

Original Board LDO Max Temp is 53.7 C

Figure 2-7 Original 1.8V_CLK LDO
Note:

Original Board LDO Max Temp is 46.9 C

Figure 2-8 Original 1.8V_PLL LDO
Note:

TPS62913 Max Temp is 52.4 C

Figure 2-9 TPS62913 1.8V Switching Converters
Note:

Original Board DC-DC Max Temp is 54.0 C

Figure 2-10 Original 1.2V Switching Converter
Note:

Original Board DC-DC Max Temp is 57.7 C

Figure 2-11 Original 0.9V Switching Converter
Note:

TPS541620 Max Temp is 59.3 C

Figure 2-12 TPS541620 0.9V and 1.2V Dual Switching Converter