A 54 µW CMOS Auto-Trimming Bandgap References (ATBGR) Achieving 90 dB PSRR for Artificial Intelligence of Things (AIoT) Chips.

An Auto-Trimming CMOS Bandgap References Circuit (ATBGR) with PSRR enhancement circuit for Artificial Intelligence of Things (AIoT) chips is presented in this paper. The ATBGR is designed with a first-order temperature compensation technique providing a stable reference voltage of 1.25 V in the ranges of input voltages from 1.65 V to 4.5 V. An auto-trimming circuit is integrated into a PTAT resistor of BGR to minimize the influences of the process variations. The four parallel resistor pairs with PMOS switches are connected in series with the PTAT resistor. The reference voltage, VREF, is compared to an external constant value, 1.25 V, through an operational amplifier, and the output of the de-multiplexer is used to configure the PMOS switches. High power supply rejection is achieved through a PSRR enhancement circuit constituting a cascaded PMOS common gate pair. The ATBGR circuit is fabricated in 180 nm CMOS technology, consuming an area of 0.03277 mm2. The auto-trimming method yields an average temperature coefficient of 9.99 ppm/°C with temperature ranges from -40 °C to 125 °C, and a power supply rejection ratio of -90 dB at 100 MHz is obtained. The line regulation of the proposed circuit is 0.434%/V with power consumption of 54.12 µW at room temperature.

A State-of-the-Art Review on CMOS Radio Frequency Power Amplifiers for Wireless Communication Systems.

Wireless communication systems have undergone significant development in recent years, particularly with the transition from fourth generation (4G) to fifth generation (5G). As the number of wireless devices and mobile data usage increase, there is a growing need for enhancements and upgrades to the current wireless communication systems. CMOS transceivers are increasingly being explored to meet the requirements of the latest wireless communication protocols and applications while achieving the goal of system-on-chip (SoC). The radio frequency power amplifier (RFPA) in a CMOS transmitter plays a crucial role in amplifying RF signals and transmitting them from the antenna. This state-of-the-art review paper presents a concise discussion of the performance metrics that are important for designing a CMOS PA, followed by an overview of the trending research on CMOS PA techniques that focuses on efficiency, linearity, and bandwidth enhancement.

A Wide-Bandwidth PVT-Reconfigurable CMOS Power Amplifier with an Integrated Tunable-Output Impedance Matching Network.

This paper proposes a wideband CMOS power amplifier (PA) with integrated digitally assisted wideband pre-distorter (DAWPD) and a transformer-integrated tunable-output impedance matching network. As a continuation of our previous research, which focused only on linearization tuning for wideband and PVT, this work emphasized improving the maximum output power, gain and PAE across the PVT variations while maintaining the linearity for a wide frequency bandwidth of 1 GHz. The DAWPD is employed at the driver stage to realize a pre-distorting characteristic for wideband linearization. The addition of the tunable-output impedance matching technique in this work provides stable output power, PAE and gain across the PVT variations, through which it improves the design's robustness, reliability and production yield. Fabricated in CMOS 130 nm with an 8-metal-layer process, the DAWPD-PA with tunable-output impedance matching can achieve an operating frequency bandwidth of 1 GHz from 1.7 to 2.7 GHz. The DAWPD-PA attained a maximum output power of 27 to 28 dBm with a peak PAE of 38.8 to 41.3%. The power gain achieved was 26.9 to 29.7 dB across the targeted frequencies. In addition, when measured with a 20 MHz LTE modulated signal, the DAWPD-PA achieved a linear output power and PAE of 24.0 to 25.1 dBm and 34.5 to 38.8% across the frequency, respectively. On top of that, in this study, the DAWPD-PA is proven to be resilient to process-voltage-temperature (PVT) variations, where it achieves stable performances via the utilization of the proposed tuning mechanisms, mainly contributed by the proposed transformer-integrated tunable-output impedance matching network.

Incidence, Management, and Risk Factors for Lower Gastrointestinal Bleeding in Renal Transplant Recipients.

BACKGROUND: There are limited convincing data regarding management and outcomes of lower gastrointestinal bleeding (LGB) in renal transplant recipients (RTR). The aim of this study was to evaluate incidence, management strategies, and risk factors associated with LGB in RTR. METHODS: Between January 2004 and December 2013, RTR with LGB were analyzed. LGB was defined as having clinical evidence of hemorrhage after upper gastrointestinal etiology was ruled out. RESULTS: There were 1578 RTR with a mean age of 50 ± 14 years at the time of transplantation. Mean follow-up time after transplantation was 57 ± 45 months. Forty-five (2.9%) patients had a documented site of LGB. The most common causes of bleeding were colitis and angiodysplasia (n = 17). Mean time to LGB after transplantation was 43 ± 36 months. Twelve patients with LGB required intervention. Three underwent colectomy, endoscopic treatment was utilized in 8, and 1 patient had angiographic embolization to control bleeding. Recurrent LGB developed in 11 patients of 42 patients who did not have surgery at the time of index bleeding. Surgical (n = 1) or endoscopic intervention (n = 4) was required in 5 of recurrent bleeders. LGB was more commonly seen in RTRs who had development of a nonfunctioning kidney (P < .0001). RTR who had an LGB had an increased overall mortality rate (not directly related to the bleeding episode) compared with those who did not have a LGB (P = .001). We did not observe any increased risk of LGB bleeding among patients who were receiving anticoagulant or anti-aggregant treatment agents (P = .76). CONCLUSIONS: Nonfunctioning kidney after transplant is a risk factor for LGB. Overall mortality rates increased after LGB in RTR. Strategies aiming to prolong transplanted kidney function may reduce the incidence of LGB and improve life expectancy in RTR.

Colonoscopic decompression should be used before neostigmine in the treatment of Ogilvie's syndrome.

BACKGROUND: Performance of urgent colonoscopy for the purposes of diagnosis and treatment of Ogilvie's syndrome remains controversial. However, no trials have directly compared neostigmine with endoscopic therapy. This study aimed to compare the effect of neostigmine and colonoscopic decompression in the treatment of Ogilvie's syndrome. METHODS: This study was designed as a retrospective, non-randomized clinical study of sequential patients. Patients who were diagnosed as having acute colonic pseudo-obstruction were separated into two groups after conservative treatment. Group 1 comprised patients who underwent colonoscopic decompression, because they had a poor first response to neostigmine treatment. Group 2 constituted patients who had a poor first response to colonoscopic decompression, and neostigmine was added to the treatment regimen. Groups 1 and 2 were compared for the success of disease management. RESULTS: In groups 1 and 2, the average age of the patients was 63.19 years (±14.71 years) and 59.45 years (±15.31 years) (p = 0.312), respectively. No significant difference was determined between the groups in terms of distribution of sex, hospital stay, etiologies, and initial cecal sizes in imaging (p > 0.05). Response to first intervention was statistically significant (p < 0.01). Also, the total response was determined statistically significant for hospital stay if colonoscopic decompression was performed (p < 0.01). No recurrence was determined during the 1-month follow-up in both groups. Although there was no etiologic factor for neostigmine response according to univariate analysis results, colonoscopic success was decreased due to age, sex, and the presence of a cardiac disease. CONCLUSIONS: Although the success rate of neostigmine treatment was significantly lower in our homogeneous groups, no significant decrease was determined in terms of hospital stay, intensive care unit stay, and requirement of colostomy compared with colonoscopic decompression. By comparison, colonoscopic decompression, which was performed by experienced endoscopists as a first-line treatment option, was more effective as an initial therapy and was more effective at avoiding a second treatment modality.

Predictors of wound dehiscence and its impact on mortality after abdominoperineal resection: data from the National Surgical Quality Improvement Program.

BACKGROUND: Wound dehiscence is a known complication following abdominoperineal resection (APR) and can have a negative impact on recovery and outcome. The aim of this study was to determine the predictors of post-APR 30-day abdominal and/or perineal wound dehiscence, readmission, and reoperation, and to assess the impact of wound dehiscence on 30-day mortality. METHODS: All patients undergoing APR between 2005 and 2012 were analyzed using the American College of Surgeons National Surgical Quality Improvement Program. RESULTS: There were 5161 patients [male = 3076 (59.6 %)] with a mean age of 61.9 ± 14.3 years. Mean body mass index was 27.4 ± 6.6 kg/m(2). The most common indication for surgery was rectal cancer (79.1 %), followed by inflammatory bowel disease (8.2 %). The overall rate of wound dehiscence was 2.7 % (n = 141). Older age (p = 0.013), baseline dyspnea (p = 0.043), smoking history (p = 0.009), and muscle flap creation (p ≤ 0.001) were independently associated with the risk of dehiscence. No association was observed between omental flap creation and dehiscence risk (p = 0.47). The 30-day readmission rate (15.6 vs. 5.6 %, p ≤ 0.001) and need for reoperation (39 vs. 6.6 %, p ≤ 0.001) were significantly higher in patients who experienced dehiscence. Dehiscence was an independent risk factor for 30-day mortality [OR = 2.69 (1.02-7.08), p = 0.045)]. CONCLUSIONS: Older age, baseline dyspnea, smoking, and the use of muscle flap were associated with higher risk of wound dehiscence following APR. Patients with wound dehiscence had a higher rate of readmission and need for reoperation, and an increased risk of 30-day mortality.