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Abstract: Realising a higher voltage application utilising bridge topologies in CMOS Power IC CMOS technology presents integration and design issues that must be solved by careful selection of the manufacturing process architecture. In this paper, we present a solution that uses a p+/p-buffer/n-epi stack to implement a 100V RESURF N-channel LDMOS high-side compatible power transistor. The device was developed and designed onto the new substrate using TCAD industrial standard softwares (TSuprem4 and Medici). Masks were designed using the Cadence Virtuoso tool set. The physical results show good transistor characteristics compatible for high-side applications. The specific resistance, RDSon, for the new device is 175mΩmm2 and breakdown voltage for both high-side and low-side operations exceeds targeted 100V. The design involved new starting material, and the test structures to measure latch-up susceptibility were also designed and manufactured. These structures were characterised and the results show minimal degradation in standard CMOS performance. [Copyright &y& Elsevier]

Background: Mapping criteria for hemodynamically tolerated, postinfarction ventricular tachycardia (VT) have been evaluated in only small series of patients.Objectives: The purpose of this study was to evaluate the utility of various mapping criteria for identifying a critical VT circuit isthmus in a post hoc analysis.Methods: Ninety VTs (cycle length 491 +/- 84 ms) were mapped in 48 patients with a prior myocardial infarction. The mapping catheter was positioned within a protected area of the reentrant circuit of the targeted VTs at 176 sites. All sites showed concealed entrainment. The predictive values of the following mapping criteria for a successful ablation site were compared: discrete isolated potential during VT, inability to dissociate the isolated potential from the VT, endocardial activation time >70 ms, matching electrogram-QRS and stimulus-QRS intervals, VT termination without global capture during pacing, stimulus-QRS/VT cycle length ratio Results: Seventy-eight of 90 VTs (87%) were successfully ablated. The area under the receiver operating characteristic curve was largest (0.89) for matching stimulus-QRS and electrogram-QRS intervals. In combination with an isolated potential that could not be dissociated from the VT, the area under the receiver operating characteristic curve increased to 0.93.Conclusion: At sites with concealed entrainment, matching stimulus-QRS and electrogram-QRS intervals were superior to other criteria in differentiating a critical isthmus from bystander or noncritical sites in postinfarction VT. [ABSTRACT FROM AUTHOR]

Background: Left atrial (LA) circumferential ablation has been reported to eliminate atrial fibrillation (AF). Whether an ablation without encirclement of the pulmonary veins (PVs) is as effective as LA circumferential ablation is not clear.Objectives: The purpose of this study was to compare the efficacy of LA circumferential ablation and nonencircling linear ablation in patients with chronic AF.Methods: Eighty patients with chronic AF were randomized to undergo LA circumferential ablation (n = 40) or nonencircling linear ablation (n = 40). In LA circumferential ablation, the PVs were encircled, with additional lines made in the mitral isthmus and posterior wall or roof. In nonencircling linear ablation, 4 +/- 1 ablation lines were created through areas of complex electrograms, with lines in the roof (38), anterior wall (36), septum (40), mitral isthmus (32), and posterior annulus (6). The endpoint of LA circumferential ablation and nonencircling linear ablation was voltage abatement.Results: LA flutter occurred in 15% after LA circumferential ablation and in 18% after nonencircling linear ablation (P = .8). A repeat ablation procedure was performed for recurrent AF in 7 and 11 patients or for atrial flutter in 6 and 4 patients after LA circumferential ablation and nonencircling linear ablation, respectively (P = .8). At 9 +/- 4 months, the prevalence of AF was 28% in the LA circumferential ablation and 25% in the nonencircling linear ablation group (P = .8). Sixty-eight percent and 60% of patients were in sinus rhythm and free of AF and atrial flutter in the absence of antiarrhythmic drug therapy after LA circumferential ablation and nonencircling linear ablation, respectively (P = .5). There were no complications.Conclusion: Nonencircling linear ablation and LA circumferential ablation are equally efficacious in eliminating chronic AF. However, the advantage of nonencircling linear ablation is that it eliminates the need for ablation along the posterior wall of the LA. Therefore, nonencircling linear ablation may avoid the small but real risk of atrioesophageal fistula formation associated with LA circumferential ablation. [ABSTRACT FROM AUTHOR]

Background: The effects of left atrial (LA) circumferential ablation on LA function in patients with atrial fibrillation (AF) have not been well described. Objectives: The purpose of this study was to determine the effect of LA circumferential ablation on LA function. Methods: Gated, multiphase, dynamic contrast-enhanced computed tomographic (CT) scans of the chest with three-dimensional reconstructions of the heart were used to calculate the LA ejection fraction (EF) in 36 patients with paroxysmal (n = 27) or chronic (n = 9) AF (mean age 55 +/- 11 years) and in 10 control subjects with no history of AF. Because CT scans had to be acquired during sinus rhythm, a CT scan was available both before and after (mean 5 +/- 1 months) LA circumferential ablation (LACA) in only 10 patients. A single CT scan was acquired in 8 patients before and in 18 patients after LACA ablation. Radiofrequency catheter ablation was performed using an 8-mm-tip catheter to encircle the pulmonary veins, with additional lines along the mitral isthmus and the roof. Results: In patients with paroxysmal AF, LA EF was lower after than before LACA (21% +/- 8% vs 32 +/- 13%, P = .003). LA EF after LA catheter ablation was similar among patients with paroxysmal AF and those with chronic AF (21% +/- 8% vs 23 +/- 13%, P = .7). However, LA EF after LA catheter ablation was lower in all patients with AF than in control subjects (21% +/- 10% vs 47% +/- 5%, P < .001). Conclusion: During medium-term follow-up, restoration of sinus rhythm by LACA results in partial return of LA function in patients with chronic AF. However, in patients with paroxysmal AF, LA catheter ablation results in decreased LA function. Whether the impairment in LA function is severe enough to predispose to LA thrombi despite elimination of AF remains to be determined. [ABSTRACT FROM AUTHOR]

Background: The coronary sinus (CS) and its branches may play a role in the genesis of various arrhythmias. Applications of radiofrequency energy within the CS may be necessary. Atrio-esophageal fistula has been recognized as a complication of ablation along the posterior left atrial wall. Objectives: The purpose of this study was to describe the in vivo topographic anatomy of the CS, esophagus, and coronary arteries using computed tomography (CT). Methods: Helical contrast CT of the heart with three-dimensional and endoscopic reconstructions was performed in 50 patients (28 men and 22 women; mean age 54 +/- 10 years). The images were reformatted to determine the relationships among the CS, adjacent blood vessels, and esophagus and to determine the nature and thickness of surrounding tissue layers. Results: Mean CS ostium diameter was 12 +/- 4 mm, and mean thickness of the periosteal fat layer was 3 +/- 2 mm. In 40 of the 50 patients (80%), the esophagus was adjacent to the CS, starting 24 +/- 9 mm from the ostium, and remained in contact for a mean length of 7 +/- 5 mm. Mean thickness of the fat layer between the esophagus and CS was 1 +/- 1 mm, and mean thickness of the anterior wall of the esophagus was 3 +/- 2 mm. In 10 patients (20%), there was no contact between the esophagus and CS. In 40 patients (80%), the right coronary artery was less than 5 mm from the CS (minimum distance 1 +/- 1 mm) over a mean length of 17 +/- 11 mm. In all patients, the circumflex artery was less than 5 mm from the CS (minimum distance 1 +/- 0.4 mm) over a mean length of 16 +/- 9 mm in patients with right-dominant coronary circulation and over a mean length of 86 +/- 11 mm in patients with left-dominant coronary circulation. Conclusion: The CS often lies very close to the esophagus and coronary arteries. During radiofrequency energy ablation in the CS, caution should be exercised to prevent injury to surrounding structures. [ABSTRACT FROM AUTHOR]

Background: Mechanical trauma has been described as a helpful guide for ablation of atrial tachycardias and accessory pathways. In postinfarction ventricular tachycardia (VT), the reentrant circuit is partly endocardial and therefore may be susceptible to catheter trauma.Objectives: The purpose of this study was to determine the prevalence and significance of VT termination resulting from catheter trauma.Methods: A consecutive series of 39 patients (mean age 68 +/- 7 years, ejection fraction 0.25 +/- 0.02) underwent left ventricular mapping for postinfarction VT. Mapping was performed during 62 hemodynamically tolerated VTs (mean cycle length 451 +/- 88 ms). Only hemodynamically tolerated VTs that did not terminate spontaneously and VTs that were reproducibly inducible were included in the study. VT termination was considered mechanical only if it was not caused by a premature depolarization.Results: In 13 of 62 VTs (21%) in 8 of 39 patients (21%), either VT terminated during catheter placement at a particular site (n = 7) or a previously reproducibly inducible VT became no longer inducible with the mapping catheter located at a particular site (n = 6). The stimulus-QRS interval was significantly shorter at sites where mechanical trauma affected the reentrant circuit compared with sites having concealed entrainment (102 +/- 56 ms vs 253 +/- 134 ms, P = .003). At the site that was susceptible to mechanical trauma, the pace map was identical or highly similar in 13 of 13 VTs. After radiofrequency ablation at these sites, the targeted VTs were no longer inducible. No patient had recurrence of the targeted VT during a mean follow-up of 15 +/- 11 months.Conclusions: Catheter contact at a critical endocardial site can interrupt postinfarction VT or prevent its induction. Radiofrequency ablation at sites of mechanical termination of VT has a high probability of success. [ABSTRACT FROM AUTHOR]

Abstract: A combination of two conventional junction isolation structures is used to produce a device, which significantly improves the blocking of minority carriers injected into the substrate of a power IC due to switching of an inductive load. Simulation results show that the connection scheme employed greatly enhances the efficiency of the structures. A substrate current reduction of up to four orders of magnitude compared to conventional junction isolation structures is achieved. The significance of doping profiles in the p-sinker region is evaluated. [Copyright &y& Elsevier]

In this paper a novel photovoltaic (PV) emulating scheme for testing maximum power point tracking (MPPT) algorithms and PV inverters has been proposed. It is constructed by the parallel connection of conventional solar panels with a DC power supply operating in current source mode. The advantages of the proposed scheme are cost-effectiveness, relatively easy implementation and indoor testing of MPPT algorithms and power converters avoiding weather and time of day dependency on solar irradiation levels. Furthermore, the proposed PV emulator avoids the bandwidth problem associated with the dc converter based PV emulating systems. Detailed circuit connection, parameters, electrical characteristics and mathematical model of the PV emulator are presented and discussed. Proposed PV emulating system has been used to test a boost DC/DC converter controlled by Perturb & Observe (P&O) MPPT algorithm. Test results confirmed the effectiveness of the proposed PV emulation system and all achieved results correspond well to the original designed values. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, load current observer based feedforward control of DC bus voltage for a three-phase active rectifier is presented. The paper focuses on: (1) design of conventional proportional-integral (PI) current controller with fastest possible response, (2) the digital current control loop time-delay compensation, (3) design of dc-link-load current observer for identifying the dc load current without using actual current sensors and (4) the feedforward control of dc bus voltage based on the designed current controller and dc link load current observer. A prototype is developed based on the proposed control scheme and expected results have been achieved. [Copyright &y& Elsevier]

Abstract: A standard 0.35 micrometer CMOS technology has been extended for 100V Power IC applications by accommodating reduced surface field (RESURF) LDMOSFET device with p-well block region or extended poly-overlap region for suppression of the drain wrapping potential. A 100V integrated H-bridge circuit suitable for driving a brushless DC motor has been designed, manufactured and tested to prove the technology. To streamline the design and integration of this power device 2D and 3D simulations have been performed. Different electrical isolation schemes to provide technology compartmentalization have also been investigated experimentally and results are discussed. [Copyright &y& Elsevier]

Abstract: A new device is proposed that utilizes a Si/SiC hetero-junction to potentially overcome one of the major issues holding back the development of SiC MOSFET technology. The proposed device makes use of a thin epitaxial layer of silicon grown on a SiC substrate, on which a high-quality MOS structure can be fabricated. Doped p-type wells in both the silicon and SiC epitaxial layers ensure that the blocking region is contained entirely within the SiC substrate, thus maximising the breakdown voltage of the device. In this study, numerical modelling methods have been applied to a Si/SiC hetero-junction MOSFET structure in order to investigate its feasibility and potential benefits over conventional SiC MOSFETs. Preliminary results on growth of thin silicon layers on SiC – which would be used in fabrication of the real device – are also reported. [Copyright &y& Elsevier]

Abstract: An investigation of the structures and design parameters of 4H–SiC trench inversion-channel MOSFETs using a two-dimensional (2D) numerical device simulation is presented. Material parameters have been adjusted appropriately for the 4H–SiC polytype and a systematic characterisation and optimization of a specific trench MOSFET with a 1.2kV blocking voltage capability has been performed. Simulations have concentrated on optimizing the p-type doping concentration at the trench bottom, to keep the breakdown electric field in the oxide under its critical value. The trench depth was also examined and optimized to give a better on-state performance. For the MOSFET structure examined, a minimized on-state resistance of 53mΩcm2 was obtained. [Copyright &y& Elsevier]