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Background and Objectives: The risks of uveitis development among pediatric patients with Down syndrome (DS) remain unclear. Therefore, we aimed to determine the risk of uveitis following a diagnosis of DS. Materials and Methods: This multi-institutional retrospective cohort study utilized the TriNetX database to identify individuals aged 18 years and younger with and without a diagnosis of DS between 1 January 2000 and 31 December 2023. The non-DS cohort consisted of randomly selected control patients matched by selected variables. This included gender, age, ethnicity, and certain comorbidities. The main outcome is the incidence of new-onset uveitis. Statistical analysis of the uveitis risk was reported using hazard ratios (HRs) and 95% confidence intervals (CIs). Separate analyses of the uveitis risk among DS patients based on age groups and gender were also performed. Results: A total of 53,993 individuals with DS (46.83% female, 58.26% white, mean age at index 5.21 ± 5.76 years) and 53,993 non-DS individuals (45.56% female, 58.28% white, mean age at index 5.21 ± 5.76 years) were recruited from the TriNetX database. Our analysis also showed no overall increased risk of uveitis among DS patients (HR: 1.33 [CI: 0.89–1.99]) compared to the non-DS cohort across the 23-year study period. Subgroup analyses based on different age groups showed that those aged 0–1 year (HR: 1.36 [CI: 0.68–2.72]), 0–5 years (HR: 1.34 [CI: 0.75–2.39]), and 6–18 years (HR: 1.15 [CI: 0.67–1.96]) were found to have no association with uveitis risk compared to their respective non-DS comparators. There was also no increased risk of uveitis among females (HR: 1.49 [CI: 0.87–2.56]) or males (HR: 0.82 [CI: 0.48–1.41]) with DS compared to their respective non-DS comparators. Conclusions: Our study found no overall increased risk of uveitis following a diagnosis of DS compared to a matched control population. [ABSTRACT FROM AUTHOR]

This document is a reply to a comment on a study about the risk of uveitis after a COVID-19 diagnosis. The authors address concerns raised about the study's generalizability to different ethnic backgrounds, the sensitivity of PCR testing, the impact of age on the results, the presence of undiagnosed uveitis cases, and the exclusion criteria for self-limited incident uveitis. They propose modifications to address these concerns and provide additional analysis to support their original findings. The authors acknowledge that uveitis can occur independently of COVID-19 but maintain that their study's large sample size and rigorous methodology support the association between COVID-19 and uveitis. [Extracted from the article]

Reports on uveitis after COVID‐19 have been limited. Our objective was to examine the risk of uveitis among COVID‐19 patients. This was a retrospective cohort study based on the TriNetX platform. The exposure group was patients with positive laboratory test result for SARS‐CoV‐2 and the comparison group was those tested negative for COVID‐19 throughout the study period. The endpoint is the new diagnoses of uveitis. This study composed of 2 105 424 patients diagnosed with COVID‐19 (55.4% female; 62.5% white; mean age at index 40.7 years) and 2 105 424 patients (55.4% female; 62.4% white; mean age at index 40.7 years) who never had COVID‐19. There was significantly increased risk of new diagnosis of uveitis since the first month after diagnosis of COVID‐19 compared with matched controls (HR: 1.18, 95% CI: 1.03–1.34) up to 24 months (HR: 1.16, 95% CI: 1.09–1.22). Our findings strengthen those previously raised by case series with a larger and multicenter study. We found that uveitis was significantly associated with COVID‐19 infection. Our findings reiterate the need for careful investigation as well as increased awareness from ophthalmologists in considering the possibility of COVID‐19 in vulnerable patients with new presentation of uveitis. [ABSTRACT FROM AUTHOR]

Background and Objectives: The identification of possible biomarkers that can predict treatment response among DME eyes is important for the individualization of treatment plans. We investigated optical coherence tomography (OCT)-based biomarkers that may predict the one-year real-life outcomes among diabetic macular edema (DME) eyes following treatment by intravitreal ranibizumab (IVR) injections. Materials and Methods: A total of 65 eyes from 35 treatment-naïve patients with DME treated with ranibizumab injection were recruited. Best-corrected visual acuity (BCVA), central retinal thickness (CRT), intraocular pressure (IOP), and OCT scans were retrospectively recorded at baseline before treatment and at 3 months, 6 months, and 12 months after treatment. The OCT scans were evaluated for biomarkers of interest, which included central retinal thickness (CRT), amount and locations of hyperreflective foci (HRF), subretinal fluid (SRF), intraretinal cysts (IRC), large outer nuclear layer cyst (LONLC), ellipsoid zone disruption (EZD), disorganization of retinal inner layers (DRIL), hard exudates (HE), epiretinal membrane (ERM), and vitreomacular interface (VMI). Correlations between these OCT biomarkers and outcome measures (visual and structural) were statistically analyzed. Results: A total of 65 eyes from 35 patients with DME were enrolled. The mean age was 64.2 ± 10.9 years old. Significant improvement in terms of mean BCVA (p < 0.005) and mean CRT was seen at final follow-up compared to baseline. The biomarkers of DRIL, LONLC, and SRF were found to be predictive for at least 50 μm CRT reduction after treatment (with odds ratio of 8.69, 8.5, and 17.58, respectively). The biomarkers of IRC, LONLC, and SRF were predictive for significant improvement in terms of BCVA and CRT after treatment. Finally, the number of HRF was predictive for both BCVA improvement and a CRT reduction of less than 100 μm after treatment. No serious complications were reported during the study. Conclusion: Our study demonstrated the utility of OCT biomarkers as therapeutic predictors of ranibizumab treatment among DME eyes. [ABSTRACT FROM AUTHOR]

To investigate whether patients with chronic kidney disease (CKD) are at increased risk of uveitis. Data was collected from the Taiwan National Health Insurance system and included patients newly diagnosed with CKD between 2000 and 2012. The endpoint of interest was a diagnosis of uveitis. 30,256 CKD patients and 121,024 matched comparisons were analyzed. CKD patients were found to have a significantly higher cumulative uveitis incidence. Through multivariate Cox regression analysis, the CKD group was found to have higher risk of developing uveitis (adjusted hazard ratio 1.51). After stratified by gender, age, and comorbidities (hypertension, diabetes, and hyperlipidemia), the increased risk of uveitis in CKD patients remained significant. Patients with CKD were found to have higher risk of developing uveitis. For patients over 18 years old and with hypertension, diabetes, or hyperlipidemia, the presence of CKD was demonstrated as an additional crucial factor for uveitis development. [ABSTRACT FROM AUTHOR]

Background and Objectives: Intravitreal injections (IVI) of vascular endothelial growth factor (VEGF) inhibitors are guideline-indicated treatments for diabetic macular edema (DME). However, some recent data have suggested that IVI VEGF inhibitors might, through systemic absorption, lead to a reduction in renal function. Our study aims to compare changes in glycated hemoglobin A1c (HbA1c) and estimated glomerular filtration rate (eGFR) between patients who received IVI ranibizumab and aflibercept treatment and patients who have not received IVI treatments. Materials and Methods: There were 17,165 DME patients with documented ophthalmology visits in the China Medical University Hospital-Clinical Research Data Repository. Those with a history of ESRD or bevacizumab treatment history, and those with missing information on HbA1c or eGFR, were excluded. After matching by age (±2 years), gender, and the year of clinical visit, 154 patients with medical treatment (including ranibizumab and aflibercept) and 154 patients without medical treatment were included in the study. The difference between HbA1c and eGFR at baseline and 3 and 12 months after the index date between the two groups was assessed. Results: Mean HbA1c and eGFR decreased between baseline and 12 months after the index date in both groups (p < 0.05). Compared with the non-treatment group, the treatment group had significantly lower HbA1c 3 and 12 months after the index date. There was no significant difference in eGFR between the two groups. In the generalized estimating equations (GEE) model, HbA1c in the treatment group was lower than the non-treatment group (−0.44%, 95% CI = −0.75, −0.14), but eGFR was similar after adjusting for age, gender, and index-year. HbA1c and eGFR decreased with the time in the adjusted GEE model (p < 0.0001) in both groups. Conclusions: This study showed that eGFR decreased with age and time and was not related to IVI anti-VEGF treatments in our tertiary referral hospital. IVI anti-VEGF therapy was also associated with better HbA1c control. It is suggested that DME patients can receive intravitreal VEGF inhibitors without inducing more renal impairment. [ABSTRACT FROM AUTHOR]

This prospective comparative case series aims to compare best-corrected visual acuity (BCVA), retinal microvasculature, and retinal structural changes in patients treated with either ranibizumab or aflibercept for macular edema (ME) secondary to treatment-naïve branch retinal vein occlusion (BRVO) by optical coherence tomography angiography (OCTA). Ten patients were enrolled with macular capillary density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) and foveal avascular zone (FAZ) measured in both eyes before and after treatment. Final central retinal thickness and BCVA improved significantly (p < 0.05), and densities of SCP and DCP of BRVO sectors were significantly lower at baseline than fellow eye counterparts and remained persistently lower during treatment, particularly in the aflibercept group (p < 0.05). SCP density, DCP density of both BRVO sectors (p = 0.0001, p < 0.0001), and non-BRVO sectors (p < 0.0001, p < 0.0001) were significantly correlated with final BCVA for diseased eyes. Using multivariate general linear model analysis, and including OCTA parameters only, but not all of the available clinical data, DCP density of BRVO sectors in both eyes was the most predictive factor for final visual outcome (probability p < 0.0001). OCTA offered further qualitative and quantitative evaluation of treatment-naïve BRVO. Judging by OCTA parameters, not only in the diseased eye but also in the fellow eye, DCP density of BRVO sectors was the most predictive factor of final visual outcome. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether patients with thyroid disease are at increased risk of uveitis.Methods: Data was collected from the Taiwan National Health Insurance system and included patients newly diagnosed with thyroid disease from 2000 to 2012. The endpoint of interest was a diagnosis of uveitis.Results: In analyzing 21,396 patients with thyroid disease, yielding 85,584 matched comparisons, patients with thyroid disease to have a significantly higher cumulative incidence of uveitis when compared to the control cohort with the Kaplan-Meier analysis. This result was further confirmed by Cox regression analysis. The increased risk was persistent in both genders. The association between thyroid disease and uveitis was stronger in patients without diabetes or hypertension.Conclusion: Patients with thyroid disease were found to have a higher risk for uveitis. For certain age groups or patients without diabetes or hypertension, the role of thyroid disease might be more crucial for uveitis development. [ABSTRACT FROM AUTHOR]

Background: To compare refractive outcomes after phacoemulsification and toric IOL implantation using two different toric calculators for initial astigmatism assessment in a real-world setting. Methods: This was a retrospective, comparative, interventional case series. Patients over 30-year-old who underwent phacoemulsification and toric IOL implantation (AcrySof® Toric IOL) by the same surgeon between 2017 and 2018 were included. Eyes with irregular astigmatism, previous corneal refractive surgery, intraocular surgery, corneal pathology, macular pathology and pupil abnormalities were excluded. IOL toricity was determined by using a calculator provided by the AcrySof Toric calculator before 2018 and Barrett Toric Calculator after 2018. Patient demographics, corneal topography, vector and preoperative and postoperative refraction were collected and analyzed at three months postoperative. Results: Thirty-two eyes of 32 patients were included in the final analysis. 0.1D for surgically induced astigmatism was used. Group 1 included 14 eyes assessed with the original (AcrySof) toric IOL calculator, and group 2 included 18 eyes assessed with the Barrett toric IOL calculator. In group 1, postoperative astigmatism less than − 1.00D, − 0.75 D, and − 0.5D was achieved in 88.2%, 76.1% and 53.7% of eyes, respectively, while, in group 2, 89% eyes achieved postoperative residual astigmatism less than 0.5D and all eyes achieved postoperative residual astigmatism less than 0.75D. The proportion of patients with lower postoperative astigmatism was significantly higher in Group 2 (p< 0.05 by chi-square test), a pattern that still held when we divided patients into multiple groups. Vector analysis with the Alpins methods also supported better outcomes in the Barrett group (0.71 D vs 0.35 D). Conclusion: The Barrett Toric calculator resulted in better results in the prediction of residual astigmatism than original (AcrySof) toric calculators. [ABSTRACT FROM AUTHOR]

The Body Composition Monitor (BCM), a multifrequency bioimpedance spectroscopy device, has been widely used to assess body composition in hemodialysis patients because its measurement is not affected by overhydration commonly seen in chronic kidney disease. We aimed to develop and validate an equation for obtaining appendicular skeletal muscle mass (ASM) from BCM taking dual-energy X-ray absorptiometry (DXA) as the reference among hemodialysis patients. A total of 322 consecutive body composition measurements with BCM and DXA in 263 hemodialysis patients were randomly divided at a ratio of 2:1 into development and validation groups. Stepwise multiple regression modeling was applied to develop the ASM prediction equation. We evaluated the model as a diagnostic tool for sarcopenia using cutoffs of ASM defined by the Asian Working Group for Sarcopenia (AWGS). We further explored the association between ASM predicted by the BCM equation and all-cause mortality in two independent cohorts: one with 326 stage 3–5 CKD patients and one with 629 hemodialysis patients. BCM yielded the following equation: ASM (kg) = −1.838 + 0.395 × total body water (L) + 0.105 × body weight (kg) + 1.231 × male sex – 0.026 × age (years) (R2 = 0.914, standard error of estimate = 1.35 kg). In the validation group, Bland–Altman reliability analysis showed no significant bias of 0.098 kg and limits of agreement ±2.440 kg. Using the AWGS criteria, the model was found to have a sensitivity of 94.1%, a specificity of 98.8%, a positive predictive value of 84.2%, and a negative predictive value of 99.6% for the diagnosis of sarcopenia. Low ASM predicted by the BCM equation was associated with significantly worse overall survival among CKD patients but not hemodialysis patients. The new BCM equation provides a feasible and valid option for assessing ASM in hemodialysis patients. [ABSTRACT FROM AUTHOR]

Background: To evaluate the efficacy of micro-incision vitrectomy surgery using a non-contact wide-angle viewing system for fovea-attached type epiretinal membrane, and to report the factors influencing the outcome. Methods: A retrospective, comparative case series that included 50 patients with fovea-attached type epiretinal membrane who received micro-incision vitrectomy surgery using a non-contact wide-angle viewing system. Results: All patients were followed-up for a minimum of 12 months. Seven cases were classified as group 1A (mainly outer retinal thickening), 17 were group 1B (more tenting of outer retina and distorted inner retina), and 26 were group 1C (prominent inner retina thickening and inward tenting of outer retina). Outcome measures included operation time, recurrent rate, postoperative BCVA, and CRT. The mean operative time was 26.2 minutes. The mean change of BCVA (LogMAR) was − 0.43 (p< 0.001). The mean change of CRT was 135.3 μm (p< 0.001). The mean change of CRT was significantly higher in group 1C. Worse preoperative BCVA, male gender, and longer operative time can predict better postoperative BCVA found by multivariate logistic regression and multiple regression models. Conclusion: Significant improvement in BCVA and CRT is noted after micro-incision vitrectomy surgery to operate fovea-attached type epiretinal membranes. Worse preoperative BCVA, male, and longer operation time could predict better improvement. These findings may assist surgeons in better evaluating the potential of this method to help their patients with epiretinal membranes. [ABSTRACT FROM AUTHOR]

To evaluate the efficacy of microincision vitrectomy surgery (MIVS) for the treatment of post-cataract surgery endophthalmitis, and to report the factors which influence the outcome. This retrospective case series included eyes with post-cataract surgery endophthalmitis that had received MIVS between June 2014 and May 2017. The anatomical and functional results were analyzed. 24 eyes of 24 patients were included with mean age 72.0 ± 8.6 years old. Best-corrected visual acuity (BCVA) improved in 70.8% of patients with a significant mean logMAR BCVA change of −0.6 ± 0.9. Positive culture rate was 25%. In all study eyes, inflammation became silent after MIVS. In univariate analysis, patients with improved BCVA have shorter duration between cataract surgery and MIVS and less likely to have positive culture results. Using degree of BCVA improvement as a continuous variable, it showed that duration between cataract surgery and MIVS had significantly negative correlation with BCVA improvement. Patients with positive culture results had significantly lower BCVA improvement. Multiple regression models also confirmed the most important outcome-influencing factors. MIVS is an efficient management for post-cataract surgery endophthalmitis. BCVA is significantly improved after MIVS. No matter in univariate or multivariate analysis, positive culture results and longer duration between cataract surgery and MIVS have significant negative effects on the outcome of post-cataract surgery endophthalmitis. Multicenter collaboration should be conducted in order to formulate better management protocols of this vision-threatening complication of cataract surgery. [ABSTRACT FROM AUTHOR]

A simultaneous dual-band dual-waveform frequency synthesizer suitable for radar applications is presented. By using a K-band integer-N phase-locked loop (PLL) in conjunction with a W-band frequency modulation loop, a K-band sinusoidal carrier and W-band frequency-modulated continuous-wave frequency chirp can be generated concurrently. Due to the single PLL architecture for dual-band signal generation, additional loop filter, phase frequency detector, and dividers are no longer required for reduced chip area and power consumption. Fabricated in a 90-nm CMOS process, the proposed circuit occupies an area of 1.26 mm $\times1.675$ mm and consumes a dc power of 67 mW from a supply voltage of 1.2 V. [ABSTRACT FROM AUTHOR]

Strong acid rain was recently observed over Northeastern China, particularly in summer in Liaoning Province where alkaline dust largely neutralized acids in the past. This seems to be related to the regional transboundary pollution and poses new challenges in acid rain control scheme in China. In order to delve into the regional transport impact, and quantify its potential contributions to such an “eruption” of acid rain over Liaoning, this paper employs an online source tagging model in coupling with the Nested Air Quality Prediction Modeling System (NAQPMS). Validation of predictions shows the model capability in reproducing key meteorological and chemical features. Acid concentration over Liaoning is more pronounced in August (average of 0.087 mg/m 3 ) with strong pollutant import from regional sources against significant depletion of basic species. Seasonal mean contributions from regional sources are assessed at both lower and upper boundary layers to elucidate the main pathways of the impact of regional sources on acid concentration over Liaoning. At the upper layer (1.2 km), regional sources contribute to acid concentration over Liaoning by 67%, mainly from Shandong (16%), Hebei (13%), Tianjin (11%) and Korean Peninsula (9%). Identified main city-receptors in Liaoning are Dandong, Dalian, Chaohu, Yingkou, Liaoyang, Jinfu, Shengyang, Panjin, Tieling, Benxi, Anshan and Fushun. At lower layer (120 m) where Liaoning local contribution is dominant (58%), regional sources account for 39% in acid concentration. However, inter-municipal acid exchanges are prominent at this layer and many cities in Liaoning are revealed as important sources of local acid production. Seasonal acid contribution average within 1.2 km-120 m attains 55%, suggesting dominance of vertical pollutant transport from regional sources towards lower boundary layer in Liaoning. As direct environmental implication, this study provides policy makers with a perspective of regulating the regional transboundary environmental impact assessment in China with application to acid rain control. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effects of dexamethasone intravitreal implant (Ozurdex) and identify risk factors for repeated treatment in patients with macula edema due to branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO).Methods: Patients followed up for at least 6 months were enrolled from 2013 to 2016. Dexamethasone intravitreal implant was given as the baseline treatment. For evaluation of dexamethasone intravitreal implant effects and complications, the demographics, medical history, best-corrected visual acuity (BCVA), intraocular pressure, and central retinal thickness (CRT) were recorded. Multivariate Cox proportional hazard model and logistic regression were used to identify factors for repeated treatment.Results: Twenty-three BRVO and 11 CRVO patients were enrolled. There were 15 males and 19 females. Fifteen (44.12%) patients needed only one dexamethasone intravitreal implant. The peak CRT and BCVA significantly improved. Comparing single-injection with multiple-injection group, age and initial CRT more than 400 μm were significantly higher in the multiple-injection group. From multivariate logistic regression and Cox proportional hazards analysis, patients with age older than 55 years and initial CRT more than 400 μm had higher risk for multiple injections.Conclusions: Patients receiving as-needed schedule of dexamethasone intravitreal implant had significant peak CRT and BCVA improvement. Age older than 55 years and initial CRT more than 400 μm were significant risk factors associated with repeated dexamethasone intravitreal implant treatment. [ABSTRACT FROM AUTHOR]

In recent years, research on location-based services has received a lot of interest, in both industry and academia, due to a wide range of potential applications. Among them, one of the active topic areas is the constraint-based route planning on a point-of-interest (POI) network. Most of the previous studies on this topic primarily consider the geographic properties of the POIs in planning a route. However, we consider that the reason that a user visits a POI is that it provides some services that the user needs. In particular, in urban environments, a POI may provide various kinds of services. Hence, the user's requests should be considered. In this paper, we address a novel problem, which is called multirequest route planning, and propose a novel framework to efficiently plan a route for serving multiple user-specified requests. The framework consists of two major modules: planning module, in which four approaches with pruning and caching strategies are proposed for planning a preliminary route, and refinement module, in which two refinement mechanisms are proposed for further enhancing the quality of the route. To our best knowledge, this is the first work on route planning that considers multiple services provided by a POI and multiple requests specified by a user, simultaneously. Finally, we perform an extensive experimental evaluation based on three real-world POI data sets and deliver excellent performance. [ABSTRACT FROM PUBLISHER]

A 45-year-old man, a case of acquired immunodeficiency syndrome, received a highly active antiretroviral therapy at the outpatient service for 4 years without regular follow-up. He experienced progressively blurred vision for 6 months and a cutaneous zoster on his back 3 months ago. He was diagnosed with progressive outer retinal necrosis by polymerase chain reaction-restriction fragment length polymorphism using an aqueous humor sample, which revealed an existence of varicella zoster virus. He was given a combination of systemic, intravitreal antiviral and a highly active antiretroviral therapy. Occlusive vasculitis, an unusual finding for progressive outer retinal necrosis, developed in both eyes 1 week after the secondary intravitreal injection. Unfortunately, his vision deteriorated to no light perception in both eyes within 2 weeks. Progressive outer retinal necrosis is characterized clinically as showing minimal or no inflammation in the aqueous and vitreous humors, absence of retinal vasculitis, and patches of yellowish spots located deep in the retina. Physicians should pay attention to this rare case of progressive outer retinal necrosis associated occlusive vasculitis with very poor prognosis in spite of aggressive treatment. [ABSTRACT FROM AUTHOR]

Background Maintenance of the optimal fluid status in hemodialysis patients is still a challenging task in daily clinical practice. A bioelectric impedance technique has been applied for evaluation of hydration status in the dialysis population in recent years, but serial observations of its role in clinical dry weight determination are lacking. In this study, serial follow-up data of a body composition monitor based on bioimpedance spectroscopy (BCM-BIS) applied in dialysis patients were analyzed to define the technique's feasibility, precision and possible role in dry weight determination. Methods BCM-BIS was applied monthly to 194 hemodialysis patients for 6 months. Intra-patient precision was analyzed. Bland–Altman analysis and repeated-measures analysis of variance (ANOVA) were used to define the relationship between the dry weights determined by BCM-BIS and by clinical judgment. Results The coefficients of variation (CVs) of fluid parameters were <5%. Serial changes in dry weight differences were compared in groups with different post-dialysis hydration status and dry weight differences decreased gradually. Bland–Altman analysis revealed that the range of these differences was significantly narrower towards the latter part of the study. The upper limit of agreement with 95% confidence interval (CI) was 1.47 L and the lower limit was −3.02 L. Conclusions BCM-BIS is precise and can be easily applied in the clinical setting. Discrepancy between the dry weights determined by BCM-BIS and by clinical judgment significantly decreased during the study. It is sensitive in dry weight determination, especially for those patients with obvious over-hydration (OH) by BCM-BIS. Patients with post-dialysis OH results beyond some critical values (>1.5 L or <−3 L) should be closely monitored. [ABSTRACT FROM PUBLISHER]

In this paper, a passive half-quadrature hybrid (HQH) is presented for multiphase signal generation at radio frequencies. Utilizing capacitance ratios as the primary design parameters, the proposed hybrid exhibits excellent magnitude and phase balance even in the presence of process and temperature variations. Therefore, it is well suited for integrated-circuit designs with on-chip capacitive elements. Using a standard 0.18-\mu\ m CMOS process, the HQH circuit is integrated with a 5.6-GHz quadrature voltage-controlled oscillator (QVCO) and four down-conversion mixers for demonstration. As the QVCO oscillation frequency sweeps from 5.4 to 5.8 GHz, the measurement results indicate a root-mean-square (rms) magnitude error less than 0.5 dB and an rms phase error ranging from 4^\circ to 7^\circ at the half-quadrature outputs without any feedback correction. [ABSTRACT FROM PUBLISHER]

This paper presents experimental CMOS RF frontends suitable for ultra-low-power and ultra-low-voltage operations. In order to achieve the desirable gain and linearity of the receiver chain at a reduced supply voltage, the current-reused bias technique and the multiple-gated transistors are employed. As for the transmitter frontend, a low-voltage double-balanced mixer is utilized to maximize the conversion gain. In addition, a differential-to-single-ended circuit is also included to increase the saturated output power. Using a standard 0.18-\mum CMOS process, the proposed circuits are realized for 5-GHz RF applications with a supply voltage of 0.6 V. The fabricated receiver frontend demonstrates a conversion gain of 14.5 dB and an IIP3 of - 16 dBm with a power consumption of 2.1 mW, while the conversion gain and the output 1-dB compression of the transmitter frontend are 12.9 dB and -4.1 dBm, respectively, provided a dc power of 6 mW. [ABSTRACT FROM PUBLISHER]

In this paper, a novel circuit topology of aCMOS divide-by-4 direct injection-locked frequency divider is presented for millimeter-wave applications. To enhance the locking range for circuit operations with a division ratio of 4, a series peaking technique is introduced in the proposed divider structure such that improved input injection efficiency can be achieved. Using a standard 0.18-\mu\ m CMOS process, a V-band frequency divider is fabricated for demonstration. Operated at a supply voltage of 1.8 V, the divider core consumes a dc power of 12.6 mW. At an incident power of 0 dBm, the fabricated circuit exhibits an input locking range of 2.44 GHz in the vicinity of 60 GHz. The measured output power and locked phase noise at 1-MHz offset are -\7 dBm and -\133 dBc/Hz, respectively. [ABSTRACT FROM AUTHOR]