Design and Simulation of a 3rd-order Discrete-Time Time-Interleaved Delta-Sigma Modulator with Shared Integrators between Two Paths

This paper presents the design and simulation of a 3rd-order two-path Discrete-Time Time-Interleaved (DTTI) ΔΣ modulator. By exploiting the concept of the time-interleaving techniques and time domain equations, a conventional 3rd-order Discrete-Time (DT) ΔΣ modulator is converted to a corresponding 3rd-order two-path DTTI counterpart. For the sake of saving power and silicon area, the integrators between the two paths of the DTTI ΔΣ modulator are shared. Using one set of integrators makes the DTTI ΔΣ modulator robust to path mismatch effects compared to the typical DTTI ΔΣ modulator which has individual integrators in all paths. A problem arises out of sharing integrators between paths which we call the delayless feedback problem. A solution for this problem is proposed in this paper and for an OverSampling Ratio (OSR) of 16 and a clock frequency of 320MHz, a maximum SNR of 76.5dB is obtained

A General Formula for Impulse-Invariant Transformation for Continuous-Time Delta-Sigma Modulators

this paper presents a generalised new formula for impulse-invariant transformation which can be used to convert an nth-order Discrete-Time (DT) ΔΣ modulator to an nth-order equivalent Continuous-Time (CT) ΔΣ modulator. Impulse-invariant transformation formulas have been published in many open literature articles for s-domain to z-domain conversion and vice-versa. However, some of the published works contain omissions and oversights. To verify the newly derived formulas, very many designs of varying orders have been tested and a representative 4th-order single-loop DT ΔΣ modulator converted to an equivalent CT ΔΣ modulator through the new formulas are presented in this paper. The simulation results confirm that the CT ΔΣ modulator which has been derived by these formulas works in accordance with the initial DT specifications without any noticeable degradation in performance in comparison to its original DT ΔΣ modulator prototype

Sensory for dementia, light and sound in long term care environment

People with dementia show behavioural change in respect to their environment. Noise and Light are the two most obvious sources of sensory stimulation in the environment, and when ignored or mismanaged, they can become important sources of under or over stimulation for the person with dementia (Dewing, 2009). The purpose of this study is to gain an understanding of the sensory implications regarding light and sound in combinations with the common disturbances pertaining to dementia patients such as anxiety, sleep deprivation, agitation and malnutrition. Implementing elements such as light panels, sound barriers and appropriate lux levels have been considered as part of the rehabilitation for dementia patients. As these aspects are underutilized in many healthcare settings, a set of instructional guidelines would be helpful in designing a dementia friendly unit or to improve the environment design of an existing unit. Of course further study must be conducted to evaluate these interventions

A 28mW 320MHz 3rd–Order Continuous-Time Time-Interleaved Delta-Sigma Modulator with 10MHz Bandwidth and 12 Bits of Resolution

this paper presents a 3rd-order two-path Continuous-Time Time-Interleaved (CTTI) delta-sigma modulator which is implemented in standard 90nm CMOS technology. The architecture uses a novel method to solve the delayless feedback path issue arising from the sharing of integrators between paths. The clock frequency of the modulator is 320MHz but integrators, quantizers and DACs operate at 160MHz. The modulator achieves a dynamic range of 12 bits over a bandwidth of 10MHz and dissipates only 28mW of power from a 1.8-V supply

Design of a Delayless Feedback Path Free 2nd-order Two-Path Time-Interleaved Discrete-Time Delta-Sigma Modulator- a New Approach

This paper presents the design procedure for a 2nd_order two-path Discrete-Time Time-Interleaved (DTTI) ΔΣ modulator from a conventional single-loop 2nd-order Discrete-Time (DT) ΔΣ modulator through the use of time domain equations and time-interleaving concepts [1]. The resulting modulator is free from the delayless feedback path and has only one set of integrators. The delayless feedback path issue in Time-Interleaved (TI) ΔΣ modulators is a critical restriction for the implementation of TI ΔΣ modulators and is effectively eliminated through the use of the approach proposed in this paper. The DTTI ΔΣ modulator requires only three op-amps and two quantizers both of which work concurrently, in comparison to the single-loop DT counterpart that also deploys two op-amps. For an OverSampling Ratio (OSR) of 16 and a clock frequency of 640MHz, our simulation results show a maximum Signal-to-Noise Ratio (SNR) for the DTTI ΔΣ modulator to be 70.5dB with an input bandwidth of 20MHz which has 15dB improvement in comparison to its single-loop, single-path DT counterpart

How to design an inclusive care, based on individuals’ social cognition capacities to improve quality of life for people with dementia?

Social isolation is one of the consequences of dementia. By progression of dementia the ability to talk, remember, and orient oneself in space gradually reduces and the need for assistance with daily tasks increases. These physical and mental abatement causes decline in social, behavioural, and emotional capabilities

Investigation of genetic variation and sexual diversity of different populations of Gracilaria corticata in the Persian Gulf and Oman Sea using ISSR markers

ISSR markers were used to determine the genetic variation and sex determination of the three life-stages of 41 samples of Gracilaria corticata from two regions of the Persian Gulf and Oman Sea namely Bostaneh and Lipar. The specimens were cultured in PES media to observe the different life stages. DNA was extracted by modified CTAB method. After screening of 20 ISSR primers, four primers were selected that produced clear reproducible fragments and were suitable to find sexual diversity for further analyses. The four primers generated 75 bands ranging from 250 to 3000 bp, corresponding to an average of 18.75 bands per primer. A set of four anchored primers amplified 75 bands out of which 100% were polymorphic among 41 samples. PIC value ranged from 0.28 to 0.33 and marker index ranged from 4.48 to 6.51 per primer. The mean value of Shannon’s index was 0.45. By using primer "AB","ABC_1" were identified three life stages of this alga. Primers "A" and "C" were also able to detect diploid tetrasporophyte but haploid males and females were determined by "A" and "C" respectively. Gst value was 0.058, indicating that 83% of the genetic diversity resided within the population. Clustering analysis using WARD algorithm based on Nei's Unbiased Measures of Genetic distance, classified the G. corticata individuals into five major groups. The PCOA data confirmed the results of clustering. The results of this study reveal that ISSR markers could be used efficiently for genetic differentiation of G. corticata individuals in different regions

Morpho-anatomical studies on red alga Gracilaria corticata in the Persian Gulf and Oman Sea

The speciemns of red algae “Gracilaria corticata” were collected from the rocky intertidal shores in Bostaneh Port in the Persian Gulf and Lipar in Oman Sea in May, June and August 2013. Anatomical, morphological structures, thallus of vegetative and reproductive samples were studied. Carpogonial and tetrasporangium stages were determined based on histological and morphological methods. The female thallus, the Cystocarp with hemispherical structure through out thallus were observed. The Spermatangial conceptacle was located deeper as the oval shape in male thallus. The tetrasporophytic stage of diploid samples was determined by the presence of tetrasporangium oval shape

Do Patients with Penetrating Abdominal Stab Wounds Require Laparotomy?

Background: The optimal management of hemodynamically stable asymptomatic patients with anterior abdominal stab wounds (AASWs) remains controversial. The goal is to identify and treat injuries in a safe cost-effective manner. Common evaluation strategies are local wound exploration (LWE), diagnostic peritoneal lavage (DPL), serial clinical assessment (SCAs) and computed tomography (CT) imaging. Making a decision about the right time to operate on a patient with a penetrating abdominal stab wound, especially those who have visceral evisceration, is a continuing challenge. Objectives: Until the year 2010, our strategy was emergency laparotomy in patients with penetrating anterior fascia and those with visceral evisceration. This survey was conducted towards evaluating the results of emergency laparotomy. So, better management can be done in patients with penetrating abdominal stab wounds. Patients and Methods: This retrospective cross-sectional study was performed on patients with abdominal penetrating trauma who referred to Al- Zahra hospital in Isfahan, Iran from October 2000 to October 2010. It should be noted that patients with abdominal blunt trauma, patients under 14 years old, those with lateral abdomen penetrating trauma and patients who had unstable hemodynamic status were excluded from the study. Medical records of patients were reviewed and demographic and clinical data were collected for all patients including: age, sex, mechanism of trauma and the results of LWE and laparotomy. Data were analyzed with PASW v.20 software. All data were expressed as mean ± SD. The distribution of nominal variables was compared using the Chi-squared test. Also diagnostic index for LWE were calculated. A two-sided P value less than 0.05 was considered to be statistically significant. Results: During the 10 year period of the study, 1100 consecutive patients with stab wounds were admitted to Al-Zahra hospital Isfahan, Iran. In total, about 150 cases had penetrating traumas in the anterior abdomen area. Sixty-three (42%) patients were operated immediately due to shock, visceral evisceration or aspiration of blood via a nasogastric tube on admission. Organ injury was seen in 78% of patients with visceral evisceration. Among these 87 cases, 29 patients’ (33.3%) anterior fascia was not penetrated in LWE. So, they were observed for several hours and discharged from the hospital without surgery. While for the remaining 58 patients (66.6%), whose LWE detected penetration of anterior abdominal fascia, laparotomy was performed which showed visceral injuries in 11 (18%) cases. Conclusions: All in all, 82 percent of laparotomies in patients with penetrated anterior abdominal fascia without visceral evisceration, who had no signs of peritoneal irritation, were negative. So, we recommended further evaluation in these patients. However, visceral evisceration is an indication for exploratory laparotomy, since in our study; the majority of patients had organ damages