FPGAs – Under the Hood by National Instruments
High-level design tools offer field-programmable gate array (FPGA) technology to engineers and scientists who have little or no digital hardware design expertise. Whether you use graphical programming, C, or VHDL, the synthesis process is quite complex and can leave you wondering how FPGAs really work. What actually happens inside the chip to make programs execute within configurable blocks of silicon? This white paper is intended for the nondigital designer who wants to understand the fundamental parts of an FPGA and how it all works “under the hood.” This information is still helpful when using high-level design tools, and can hopefully shed some light on the inner workings of an extraordinary technology. Every FPGA chip is made up of a finite number of predefined resources with programmable interconnects to implement a reconfigurable digital circuit. Figure 1. The Different Parts of an FPGA FPGA chip specifications include the amount of configurable logic blocks, the number of fixed function logic blocks, such as multipliers, and size of memory resources like embedded block RAM. There are many other parts to an FPGA chip, but these are typically the most important when selecting and comparing FPGAs for a particular application.