A Novel Speculative Pseudo-Parallel Delta-Sigma Modulator Using FPGAs to produce a high-speed digital signal for use in MIMO transmission systems

Abstract

As digital communication using MIMO antenna technology has emerged as a significant technological breakthrough in modern communications, the need for reconfigurable experimental MIMO systems has increased. This project is a feasibility study of using !⌃ modulators for generating high-speed digital signals on an FPGA chip synchronized to one local oscillator. The targeted performance specifications are a 1 GHz carrier frequency, 100 MHz bandwidth, and 45 dB in-band SNDR. The approach used to achieve the performance specifications is a novel speculative pseudo-parallel !⌃ modulator based on the the method for unrolling a !⌃ modulator proposed by Hatami et al. The speculative modulator structure, although it fails to achieve the tentative system specifications, exhibits a 46 % increase in operating frequency versus the regular Hatami structure. The speculative modulator structure has the potential for further investigation and design space exploration. The main reason for failing to reach the performance goal is suboptimal mapping in the FPGA chip, which leads to relatively long routing delays with 69 % of the delay situated in routing.