FPGAs for DSP Hardware

- the advantages and disadvantages of using FPGAs rather than DSP processors in the DSP hardware.

When designing the hardware system for a DSP application it is necessary to carefully consider the approach that will be taken. One of the fundamental decisions involves whether to use a standard DSP processor, or whether to use an FPGA in the DSP hardware. Each has its own advantages and they need to be carefully balanced at the earliest stages of the design.

DSP processor

A DSP processor is a specialised processor that is designed specifically for operating complex mathematically orientated intensive calculations very swiftly. As processing needs to be undertaken almost in real time, the speed of the processor is one of the main limiting performance criteria for the performance of the system For example very steep filters need more processing than those that are not so steep, etc..

While DSP processors, despite their sophistication in terms of processing have limitations, they also have advantages. One of these is in their cost. They may still be expensive by some standards, but they are nevertheless cheaper than their counterparts, the FPGA.

FPGAs for DSP

The other approach that many adopt is to use an FPGA as the core of the DSP hardware. These devices can be programmed and there are many set cores that can be used to provide the routines that are required. For example if a filter is required, then it is possible to tailor circuitry within the FPGA to undertake this. Similarly other functions can be programmed in on top of the basic processor. In this way the FPGA is able to be programmed to provide a highly efficient and tailored solution.

The main disadvantage of the FPGA is its cost. FPGAs are more costly that DSP processors and therefore performance has to be weighed against cost.

Summary

FPGAs and DSP processors provide two very different approaches to the design of DSP hardware systems. Each have their own advantages. There are many high sampling rate applications that an FPGA does easily, while the DSP could not. Equally, there are many complex software problems that the FPGA cannot address.