SBAA682 April   2025 AFE7728D , AFE7768D , AFE7769D

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Acronyms Used in This Document
  5. 2Distributive Antenna System
  6. 3Repeater System
  7. 4Goals of DAS and Repeater Design
  8. 5RF Repeater System Without FPGA/ASIC
  9.   10
  10. 6Overcoming Bandpass Filter Effects From Cable Dispersions and Multi-Path
  11. 7Summary

4 Goals of DAS and Repeater Design

Regardless of the design for the DAS or repeater system, the goals of the system are to achieve the following:

  • Direct RF signal transfer and redistribution that is transparent to the user. The user does not receive any unwanted noise on top of the existing voice or data transfer. The base station does not receive any unwanted noise on top of existing signal.
  • Enhances signal strength and signal coverage. The user does not experience any lack of coverage as they move into any buildings. (1)
  • Introduces zero latency to the RF input to the RF output. Through the redistribution process, the user experiences delay in voice or data transfer.

With the above design goals, the system designers can look into the AFE77xxD family of integrated transceiver (1) with CFR and DPD built to fulfill requirements through the following features:

  • Support of multple RF operating bands from both the 4G and 5G spectrums. For example, the AFE77xxD family of devices can support 2T2R1FB operating in FDD RF bands (for instance, B1, B3, and B7), while the other 2T2R1FB operating in TDD RF bands (N41, N77, and N79).
  • Up to 4x RF PLLs to support multiple operating RF bands. With flexible on-chip low IF NCO on both DDC and DUC side, the device can support up to three RF bands.
  • Integrated CFR and DPD block on the RF transceiver. This offloads all digital logic resources from FPGA or digital ASIC.
  • Instantaneous bandwidth of 300MHz support. The interface rate for RX DDC and TX DUC chains can support up to 368.64MSPS of interface rate, which translates to about 300MHz of maximum output and input bandwidth out of the transceiver. The CFR and DPD rate can support the linearization of the entire 300MHz of bandwidth.
  • Up to 4x SerDes transmitter (STX) and 4x SerDes receiver (SRX) with 32.5Gbps of SerDes rate. With integrated JESD204C support, the RF transceiver can support high density data transfer.
  • Lineariztion of the power amplifiers of up to 50dBm of PA rated output power. Designers can utilize one PCB solution to support DAS, repeater, and macro remote radio applications.
  • Direct DDC to DUC loopback mode to further reduce digital latency in DAS and repeater applications.
1. Digital pre-distortion is a technique to push the boundary of the RF power amplifier in the transmitter chain, and therefore increases the signal coverage. The AFE7769D family of devices with integrated DPD can maximize PA output power, and hence improve the coverage.
1. For details to the AFE7769D family of devices, see the AFE77xxD Quad/Dual-Channel RF Transceiver With Dual Feedback Paths Integrating CFR/DPD Data Sheet (SBASAG4).