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Settling time is an important performance metric in digital-to-analog converters (DACs) that are used for dynamic calibration applications. To obtain an area efficient DAC design, periodic sequences are generated from sigma-delta modulators (ΣΔMs) using software, stores the sequence in memory and then passes it to a low-pass filter (LPF). In this brief, the sigma-delta (ΣΔ) bitstream generated in software will be optimized such that it yields a system that settles faster and is more area efficient. Two optimization routines are used, namely, serial method and random method algorithms. The random method is chosen to optimize the ΣΔ bitstreams for its computational simplicity. It will be shown, that using the random method routine provides at least 46% improvement in settling time performance of a 12-bit DAC, used in the paper as a design example. Moreover, it offers silicon area savings by at least 10% for resistor components and 35% for capacitor components. Similar results were obtained for 8 to 11 bits of resolution.

Background Compared with off-pump surgeries, cardiopulmonary bypass (CPB) is associated with a high systemic inflammatory response and with substantial myocardial injury, especially in high-risk subgroups. Every effort should be exerted to minimize the role of CPB without affecting the safety and outcome. Classically, aortic arch surgeries were done using CPB and deep circulatory arrest together with cerebral brain protection strategies. With the development of endovascular techniques, the role of CPB decreased. Management of aortic arch pathologies carries special needs, specifically rerouting of the great vessels and preparing a landing zone. Objectives To assess the effectiveness and safety of off-pump aortic arch debranching during type I hybrid aortic arch repair. Patients and methods We report our single-center experience of rerouting aortic arch branches (debranching) without using CPB, consisting of bypass grafting of the aortic arch branches off pump, preparing a landing zone for endovascular aortic repair. The preoperative, operative, and postoperative data were collected and analyzed retrospectively. Starting from 2015, 20 low-risk patients were subjected to type I aortic arch hybrid repair, whereas the Dacron tube graft was anastomosed to a normal ascending aorta, preparing a landing zone to the subsequent stenting of arch and descending aorta. CPB was used in 10 patients, and off-pump technique was used in the remaining group. Preoperative, operative, and postoperative data were collected and analyzed to compare the results. Results All surgeries went uneventful, with mean operative time of 141.5 ± 24.3 min for group I (on-pump group) and 137.5 ± 14.6 for group II (off-pump group). There were no conversions to CPB in off-pump group. There was no sternotomy for bleeding in off-pump group, compared with only one patient explored for postoperative bleeding in CPB group. All patients in both groups went without any neurological deficit of significance, with no mortality in the 30 days of follow-up. Conclusion Off-pump debranching of aortic arch followed by endovascular repair is a safe and reproducible technique, compared with the gold standard technique using CPB. However, further efforts using intraoperative cerebral perfusion monitoring techniques should be considered in the future.