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A Reconfigurable FPGA Architecture for DSP Transforms. Subramanian Rama Vishnu Vijayaraghavan. OUTLINE. Motivation Reconfigurable FPGA’s DSP Transforms, Breakdown & Applications Communication Graphs& Proposed Architecture Imaginary Radix Complex Multiplication Accomplished Work
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A Reconfigurable FPGA Architecture for DSP Transforms Subramanian Rama Vishnu Vijayaraghavan
OUTLINE • Motivation • Reconfigurable FPGA’s • DSP Transforms, Breakdown & Applications • Communication Graphs& Proposed Architecture • Imaginary Radix Complex Multiplication • Accomplished Work • Conclusion
Motivation • Dedicated VLSI Architectures for Orthogonal Transforms – FFT, DCT, Convolution, Correlation • Dedicated VLSI Architectures for Non- Orthogonal Transforms – Gabor, Wavelet • Not many Architectures for Both – Current Day Applications like Handhelds, Mobile Phones, etc. require such DSP capabilities
Need for Reconfigurable Architecture • Multiple Orthogonal & Non-Orthogonal Transforms can be broken down to a basic set of Building blocks (DCT,DST, multipliers and Adders) • Handheld devices don’t require much Multiprocessing – No need to waste hardware • Increased Fault-Tolerance By Reconfiguration and Redundancy
BATTERY (40+ lbs) AREA & POWER • INCREASING PROMINENCE OF PORTABLE SYSTEMS • Cell Phones • Personal Digital Assistants • Tablet PC’s • Need for Low Power & Area • Battery Technology not kept pace with Semiconductor Technology
DISCRETE FOURIER TRANSFORM Traditional DFT Breakdown of 1D DFT Breakdown of 2D DFT APPLICATIONS: • Image Processing • Orthogonal Frequency Division Multiplexing
Discrete Gabor Transform Gabor Transform and Coefficients Breakdown Applications • Speech Processing / Voice Recognition • Image Compression
Discrete Convolution Applications • Image Manipulation • Sound Processing
Convolution Operation (Contd.) Computational complexity: 2 DCT, 2 DST,4 real multiplications and 2 real additions
Imaginary Radix Representation • A imaginary number system, Donald Knuth, Communications of the ACM • Concept: a + ib = A – Interleave both real and Imaginary parts • # of multiplications get reduced to one • Preserve Interleaving even during multiplication • Requires slight modifications in multiplier design (one reason for migrating to FPGA)
Convolution Operation (using Complex Representation) Computational complexity: 2 DCT, 2 DST,1 complex multiplication (same as real multiplication methodology)
Convolution using Complex Representation - Communication Graph
Work so far • Design & Synthesis of Basic Building Blocks • DCT • DST • Parallel Array Multiplier • Reconfiguration Unit • Partial Integration • Work to be done: • Complete Integration • Functional Correctness Check
CONCLUSION Need for multiple transforms on same chip • Mobile devices, Handhelds • Not much multiprocessing required Use of Reconfigurable FPGA’s • Reduces • AREA • Increases • Functionality • Fault Tolerance