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Your search keyword '"Kumar, Ch Uday"' showing total 8 results
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8 results on '"Kumar, Ch Uday"'

6. 1.5V, 2.4GHz highly linear CMOS downconversion mixer

Author

Kumar, Ch. Uday and Parikh, Chetan D.

Subjects
Microwave integrated circuits, Radio frequency, Low-voltage integrated circuits, Integrated circuits, Very high speed integrated circuits, Metal oxide semiconductor Complementary, Design and construction
Abstract

In the tremendous growth of wireless handheld devices, low power consumption becomes a major consideration in radio frequency integrated circuit (RFIC) designs. This thesis explores low voltage low power RFIC design for CMOS mixer through their applications in a RF front-end transceiver.A highly linear CMOS down-conversion mixer is designed to operate at 1.5V for single battery solution. Mixer perform frequency down-conversion from a 2.4GHz radio frequency (RF) input signal to a 100MHz intermediate frequency (IF) output signal. The mixer circuit has been simulated in TSMC 0.18μm CMOS technology. Low voltage operation is achieved by using a folded cascode topology. The mixer uses a wide range constant gm cell at input RF stage to increase the linearity (IIP3) performance. The proposed mixer has 0.92dB conversion gain, 17.7dB noise figure, 3.08 1 dB compression point (P-1 dB), 13.8dBm third-order input intercept point (IIP3) and consumes 8.1mW DC power at 1.5V supply voltage. The design ensures that all the transistors remain in saturation, and mixer does perform satisfactorily for +/-50mV variation of the threshold voltage from the nominal value for both NMOS and PMOS transistors. The mixer is simulated for +/- 50mV threshold voltage variations for both NMOS and PMOS transistors. Temperature effects on this circuit were also investigated.

Published
2008

8. Effect of vitamin B 12 supplementation on retinal lesions in diabetic rats.

Author

Reddy SS, Prabhakar YK, Kumar CU, Reddy PY, and Reddy GB

Subjects
Activating Transcription Factor 6 blood, Animals, Apoptosis physiology, Blood Glucose drug effects, Body Weight drug effects, Caspase 12 blood, Chromatography, High Pressure Liquid, Diabetes Mellitus, Experimental drug therapy, Diabetes Mellitus, Experimental metabolism, Endoplasmic Reticulum Chaperone BiP, Endoplasmic Reticulum Stress physiology, Glial Fibrillary Acidic Protein blood, Heat-Shock Proteins blood, Homocysteine blood, Hypoxia-Inducible Factor 1, alpha Subunit blood, Immunohistochemistry, Male, Radioimmunoassay, Rats, Rats, Sprague-Dawley, Rhodopsin blood, Transcription Factor CHOP blood, Vascular Endothelial Growth Factor A blood, Vitamin B 12 blood, X-Box Binding Protein 1 blood, Apoptosis drug effects, Diabetes Mellitus, Experimental blood, Diabetic Retinopathy blood, Diabetic Retinopathy diet therapy, Endoplasmic Reticulum Stress drug effects, Vitamin B 12 administration & dosage
Abstract

Purpose: Diabetic retinopathy (DR) is the most common complication of diabetes involving microvasculature and neuronal alterations in the retina. Previously, we reported that vitamin B 12 deficiency could be an independent risk factor for DR in humans. However, the effect of vitamin B 12 supplementation in experimental DR is unknown. Thus, in this study, we investigated the impact of dietary supplementation of vitamin B 12 on retinal changes in diabetic rats., Methods: Diabetes was induced in 2-month-old Sprague-Dawley rats and maintained for 4 months. One group of diabetic rats were fed normal levels of vitamin B 12 , and one group double the quantity of vitamin B 12 (50 µg/kg diet). Vitamin B 12 and homocysteine levels in the plasma were analyzed with radioimmunoassay (RIA) and high-performance liquid chromatography (HPLC), respectively. At the end of 4 months of experimentation, the eyeballs were collected. Retinal changes were analyzed with hematoxylin and eosin (H&E) staining, immunoblotting, and immunofluorescence methods., Results: Dietary supplementation of vitamin B 12 had no effect on food intake, bodyweight, fasting blood glucose, and plasma homocysteine levels in the diabetic rats. However, vitamin B 12 supplementation prevented loss of rhodopsin, and overexpression of VEGF, and completely prevented overexpression of HIF1α, GFAP, and endoplasmic reticulum (ER) stress markers (GRP78, ATF6α, XBP1, CHOP, and caspase 12) in the diabetic rat retina. Further, vitamin B 12 ameliorated apoptosis in the retina as shown with terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and prevented retinal thinning., Conclusions: Vitamin B 12 supplementation of diabetic rats appeared to be beneficial by circumventing retinal hypoxia, VEGF overexpression, and ER stress-mediated cell death in the retina. The present study adds another potential therapeutic strategy of vitamin B 12 in diabetes., (Copyright © 2020 Molecular Vision.)

Published
2020

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