Fpga Signal Processing Using Sigma-delta Modulation

While Σ∆M techniques [l, 2] are applied widely in analog conversion sub-systems, both analog-to-digital (ADC) and digital-to-analog (DAC) converters. these methods have enjoyed much less exposure in the broader application domain, where flexible and configurable solutions, traditionally supplied via a software DSP (soft-DSP), are required. And this limited level of exposure is easy to understand. Most, if not all, of the efficiencies and optimizations afforded by Σ∆M are hardware oriented and so cannot be capitalized on in the fixed precision pre-defined datapath found in a soft-DSP processor. This limitation, of course, does not exist in a field programmable gate array (FPGA) DSP solution. With FPGAs the designer has complete control of the silicon to implement any desired datapath and employ optimal word precisions in the system with the objective of producing a design that satisfies the specifications in the most economically sensitive manner . While implementation of a digital Σ∆ ASIC (application specific integrated circuit) is of course possible, economic constraints make the implementation of such a building block that would provide the flexibility, and be generic enough to cover a broad market cross-section, impractical. FPGA based hardware provides a solution to this problem. FPGAs are an off-the-shelf commodity item that provide a silicon feature set ideal for constructing high-performance DSP systems. These devices maintain the flexibility of software based solutions. while providing levels of performance that match, and often exceed ASIC solutions. Σ∆