M9451A-DPD PXIe Measurement Accelerator

M9451A-DPD PXIe Measurement Accelerator

Data Sheets

Keysight Technologies

M9451A-DPD PXIe Measurement Accelerator

with Digital Pre-Distortion & Envelope Tracking Gateware

Data Sheet

Overview

The M9451A-DPD shows what is possible when you combine state-of-the art FPGAs with Keysight Technologies, Inc.’s trusted measurement expertise and PXIe high speed data handling. The trusted DPD and ET measurement algorithms were built after years of close cooperation with leading wireless manufacturing customers.

As part of Keysight’s RF PA/FEM Characterization and Test, Reference Solution, this combination provides unprecedented performance for demanding envelope tracking and digital pre-distortion measurements required for testing modern power amplifiers (PAs) and front-end modules (FEMs). Hardware acceleration provides better than 10x speed improvement over Keysight’s previous host-based Reference Solution, with closed/open loop digital pre-distortion (DPD) and envelope tracking (ET) measurements taking just tens of milliseconds and overall measurement times less than 100 msec.

Applications

  • Power amplifier testing
  • Front-end module testing
  • Envelope tracking
  • Digital pre-distortion

Key Features

The M9451A-DPD significantly speeds up DPD/ET test applications that use the N7614B Signal Studio Power Amplifier Test software. To simplify porting, the M9451A-DPD’s application programming interface (API) is very similar to the N7614B API. Key features include:

Digital Pre-Distortion

  • Open or closed loop
  • PA optimization techniques: Look up table (LUT)
  • Fast peer-to-peer (P2P) data transfer to/from PXI signal generator and signal analyzer
  • Envelope Tracking
  • Hardware accelerated envelope tracking waveform generation
  • Fast data transfer to arbitrary waveform generator (AWG)

Block Diagram: Digital Pre-Distortion and Envelope Tracking

The highlighted box shows the key functions of the digital pre-distortion (DPD) and envelope tracking (ET) gateware in the M9451A PXIe measurement accelerator. Data cylinders are allocated blocks of IQ data in the M9451A memory. Rectangles represent algorithms implemented in the accelerator. Test software controls how data is processed by passing “data handles” associated with each data cylinder to the API method associated with each algorithm rectangle. Peer-to-peer (P2P) PCI Express® technology is used to achieve fast data transfers between the M9451A memory and the M9381A PXIe vector signal generator (VSG) hardware.

The ideal reference waveform, without pre-distortion, is first loaded into the M9381A PXIe VSG ARB memory and then transferred to the M9451A using P2P. After the model extraction algorithm computes a lookup table (LUT), or other coefficients, the pre-distorter creates a pre-distorted waveform in the PA In cylinder. P2P is used to transfer the pre-distorted waveform data to the VSG ARB memory. P2P PCI Express technology is also used to transfer measurement data from the M9391A or M9393A PXIe vector signal analyzer hardware to the M9451A hardware.

The M9451A-DPD PXIe measurement accelerator with DPD and ET gateware consists of two key parts:

1. M9451A PXIe measurement accelerator with an IVI driver and soft front panel (SFP). The IVI driver provides API access to accelerator configuration and initialization features. The SFP provides diagnostic information and tools to update the M9451A gateware.

2. Option DPD adds the ET and DPD acceleration software library and associated FPGA gateware that executes in the M9451A hardware. The library’s API is modeled after the N7614B Signal Studio for Power Amplifier Test software.

To utilize the M9451A-DPD as part of your test software, example open source code is available as part of the Keysight RF PA/FEM Characterization and Test, Reference Solution. For more information about the Reference Solution, visit www.keysight.com/ find/solution-padvt.