{"id":3272,"date":"2011-06-30T20:36:51","date_gmt":"2011-06-30T20:36:51","guid":{"rendered":"https:\/\/mtlsites.mit.edu\/annual_reports\/2011\/?p=3272"},"modified":"2011-08-02T17:00:41","modified_gmt":"2011-08-02T17:00:41","slug":"continuous-time-delta-sigma-analog-to-digital-converters-for-application-to-a-multiple-input-multiple-output-system","status":"publish","type":"post","link":"https:\/\/mtlsites.mit.edu\/annual_reports\/2011\/continuous-time-delta-sigma-analog-to-digital-converters-for-application-to-a-multiple-input-multiple-output-system\/","title":{"rendered":"Continuous-Time Delta-Sigma Analog-to-Digital Converters for Application to a Multiple-Input Multiple-Output System"},"content":{"rendered":"

Wireless communication technology is rapidly advancing, and new wireless applications are continuously developed. Figure 1 shows each application and the required dynamic range [1<\/a>] <\/sup>. The new wireless applications demand wideband and high-resolution data converters. In this situation, delta-sigma (\u0394\u03a3 ) analog-to-digital converters (ADCs) are suitable, because they provide low-power and high-resolution characteristics. These \u0394\u03a3 \u00a0ADCs can be implemented in either a discrete-time (DT) or a continuous-time (CT) structure. Since DT \u0394\u03a3 ADCs, based on switched capacitors, require op amp settling within each half clock period, the gain-bandwidth requirement for the op amp is rather high. The CT \u0394\u03a3 ADCs require much lower gain-bandwidth. Thus, it is possible for CT \u0394\u03a3 ADCs to function at higher sampling frequency and achieve wide bandwidth compared to DT \u0394\u03a3 ADCs. In addition, since the CT \u0394\u03a3 \u00a0ADCs are more power-efficient and have an inherent anti-aliasing property, they are more suitable for the demanding new wireless applications.<\/p>\n

This project focuses on the design of CT \u0394\u03a3 ADCs, and specifically for the application in Multiple-Input Multiple-Output wireless receivers. For this application, each CT \u0394\u03a3 ADC in a channel must provide wide bandwidth and high dynamic range at low power consumption. Recent state-of-art CT \u0394\u03a3 ADCs did not achieve wide enough bandwidth or high enough dynamic range for such application [2<\/a>] <\/sup> [3<\/a>] <\/sup>. We are investigating new types of noise-coupled time-interleaved \u0394\u03a3 ADCs [1<\/a>] <\/sup> for MIMO systems. Figure 2 shows the overall structure of noise-coupled time-interleaved ADCs. We are currently investigating techniques that exploit correlation between channels in multi-channel noise coupled system.<\/p>\n\n\t\t