SLVAF52B July   2021  – November 2021 AFE8092 , TPS62913

 

  1.   Trademarks
  2. 1Introduction
  3. 2System Description
    1. 2.1 AFE80xx Noise and Ripple Requirements
    2. 2.2 AFE80xx Supply Settling and EVM for TDD Operations
    3. 2.3 Block Diagram
      1. 2.3.1 Proposed Power Architecture
      2. 2.3.2 Power Sequencing
    4. 2.4 Power Supply Design Consideration
  4. 3Tests and Results
    1. 3.1 Test Methodology
      1. 3.1.1 Phase Noise (Transmit) (dBc/Hz)
      2. 3.1.2 EVM for Frequency Division Multiplexing (FDD) Mode(%)
      3. 3.1.3 EVM for TDD Mode(%)
      4. 3.1.4 Receive (RX) Spectrum (Power Supply Spurious)
      5. 3.1.5 Power Efficiency
    2. 3.2 Test Conditions
    3. 3.3 Test Results
      1. 3.3.1 Phase Noise
      2. 3.3.2 EVM for FDD Mode
      3. 3.3.3 EVM for TDD Mode
      4. 3.3.4 RX Spectrum
      5. 3.3.5 Power Efficiency
  5. 4Conclusion
  6. 5References
  7. 6Revision History

Abstract

Demystifying and Mitigating Power Supply Ripple and Noise Implication on AFE8092 AFE RF performance application note describes the significance of power supply impact on key RF Performance and explains the high-efficiency power topology to meet the same. The application note covers the following key points.

  • Understanding Power Supply Ripple Modulation into RF spectrum for AFE8092 and deriving noise and ripple specification.
  • Key measurement results showing implication of power supply on RF performance and design consideration for meeting RF metrics is discussed which includes Error Vector Magnitude (EVM), Phase Noise Plot for 5G NR Spectrum.
  • The noise sensitive 1.8-V Analog rails of the AFE8092 are supplied using the TPS62913 switching regulators without the need for Low-Dropout Linear Regulators (LDOs) while maintaining the same performance as the original design. The LMK04828 is also supplied by the TPS62913.
  • The digital core power rails of 0.9 V and mixed signal 1.2-V rails are powered by the TPS543820 with passive ripple filtering meeting power supply ripple restrictions.
  • The design is applicable to the AFE80xx and other AFEs that require low noise power supplies that are size constrained and thermal constrained. Examples of applications are Remote Radio Units (RRU), Active Antenna Systems (AAS), Distributed Antenna Systems (DAS), small cell base stations, and repeaters.