JED - February 2016 - (Page 33)

TECHNOLOGY SURVEY A SAMPLING OF FPGA BOARDS FOR EW AND SIGINT APPLICATIONS By Ollie Holt Input Input Input CLB CLB Input CLB CLB Input CLB CLB ... ... ... Input CLB CLB ... Output Output ... Input Input CLB CLB Output CLB CLB Output CLB CLB Output CLB CLB Output Output Output Figure 1: Early example of Configurable Logic Blocks (CLBs). As CLB operations became more complex with advancing technology, most CLB operations were replaced with Look Up Tables (LUTs). The contents of the LUTs are set up within the FPGA at power up and these contents define the desired output of the CLB. The exact numbers and features of CLBs are different in different devices, but every CLB contains a configurable input switch matrix, programmable logic, arithmetic functions, shift registers, and LUTs and/or RAM. FPGAs provide support for many different types of input and output (I/O) standards. The I/O of an FPGA is typically grouped in banks designed to support different I/O standards. Typical FPGAs provide several of these banks. Today's FPGAs also have memory and can contain multiple Power PC cores, or more popular processing cores such as the MicroBlaze or NiosII. A "core" is a predefined complex function used in making an FPGA. Most FPGA suppliers have libraries of these cores for any user of their product and cores are also available for purchase from most third-party vendors or via "open source." In selecting an FPGA, the major things to look for include the number of logic cells, the number of digital signal processors (DSPs), whether the FPGA can be used for signal processing, the amount of memory available, and the I/O types implemented. The first survey item is the board function. Here, the user will need to determine if the FPGA board provides enough logic cells, DSPs, user memory, and I/O types to match design needs. Additionally, the board may contain other support circuits that do not have to be provided by additional modules such as analog-to-digital converters (ADCs), digitalto-analog converters (DACs), and processors. The next column defines the type of FPGA and any additional processors included. Defining the FPGA board type aids in determining how much capability the board may support and allows the user to search for available "cores" that may support the desired application. Next, the memory column should be examined in two ways: some boards will have both the memory contained on the FPGA and additional on-board memory, while others may just list the additional memory on the board. The format column defines the board size and whether the board complies with a standard format. The second part of the complete system equation is the bus format. This question is addressed in the column defining bus and I/O types available. The final columns define the operational environment for the board and power consumption. Another item that must be considered when selecting an FPGA for your design is the support tools. The major FPGA manufacturers provide tools and evaluation kits for simulating and modeling your design. Select an FPGA family that has the tools that support your design needs and also check the availability of "cores" that can make the design effort easier. JED's March Survey will cover microwave power modules (MPMs), traveling wave tubes (TWTs) and TWT amplifiers (TWTAs). The Journal of Electronic Defense | February 2016 T his month's JED survey looks at Field Programmable Gate Array (FPGA) boards for electronic warfare (EW) and signals intelligence (SIGINT) applications. With the ever-increasing use of FPGAs to simplify system design, many companies provide multifunction FPGA boards in typical Commercial-off-the-shelf (COTS) form factors. These COTS boards are being used frequently in EW systems due to their wide availability, programmability and versatility. Before discussing complete FPGA boards though, let's take a closer look at FPGAs. An FPGA is a semiconductor chip that contains many programmable logic components that can be interconnected as needed by the EW system designer to perform whatever function is needed. These programmable logic components can either be Configurable Logic Blocks (CLBs) or Logic Array Blocks (LABs). CLBs are the basic building blocks of an FPGA. A simple diagram of an early CLB is shown in Figure 1. By combining groups of CLBs, a set of logic functions can be created to generate a desired output. The switches between each CLB determine what inputs are used and where outputs are sent. 33

Table of Contents for the Digital Edition of JED - February 2016

The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
World Report
Alternatives to Positioning, Navigation and Timing
Future Operating Environment 2035
Technology Survey: FPGA Boards
The Heat is On
EW 101
AOC News
Index of Advertisers
JED Quick Look

JED - February 2016