Signal processing at 250 MHz using high-performance FPGA's

Abstract

This paper describes an application in high-performance signal processing using reconfigurable computing engines. The application is a 250 MHz cross-correlator for radio astronomy and was developed using the fastest available Xilinx FPGA's. We will report experimental results on the operation of CMOS FPGA's at 250 MHz, and describe the architectural innovations required to build a 250 MHz reconfigurable signal processor. Extensions of the technique to a variety of high-performance real-time signal processing algorithms are discussed. The results of this design work provide important clues as to how to improve FPGA architectures to better support real-time signal processing at hundreds of MHz. In particular, direct routing resources between logic elements are critical to preserving high performance. These routing resources need to be symmetric in order to allow for two-way communications between logic elements. Four-way symmetry and regularity would allow for orthogonal transformations of processing elements in a hierarchical fashion. Finally, experimental results indicate that clock buffering is frequently the cause of ultimate failure in speed and performance tests. Wave pipelining techniques may be suitable in clock distribution to improve performance to match that of other elements in the system.