The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform
Waleed Khalil - One of the best experts on this subject based on the ideXlab platform.
-
ISCAS - Analytical and experimental study of tuning range limitation in mm-wave CMOS LC-VCOs
2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013Co-Authors: Salma Elabd, Jamin J. Mccue, Waleed KhalilAbstract:In this paper, we present an analytical model for predicting the tuning range of CMOS mm-wave LC voltage-controlled oscillators (LC-VCOs). A detailed analysis of the frequency dependent quality factor (Q) of the LC-Tank is performed to characterize the Tank Loss. The frequency dependent Q is used to size the transconductance (gm) of the cross-coupled pair to satisfy the VCO startup condition. The relationship between the cross-coupled pair gm and the operating frequency is also derived. With the above relationships, the frequency dependent tuning range is further calculated and compared with simulation results. To verify the analysis, three CMOS mm-wave VCOs are fabricated in a 130 nm CMOS process. The measured tuning range of the 26 GHz, 34 GHz and 40 GHz VCO is 25%, 21% and 18%, respectively, which is consistent with the presented tuning range model.
Terumi Inagaki - One of the best experts on this subject based on the ideXlab platform.
-
Loss analysis of gravitation vortex type water turbine and influence of flow rate on the turbine’s performance
Renewable Energy, 2020Co-Authors: Yasuyuki Nishi, Ryouta Suzuo, Daichi Sukemori, Terumi InagakiAbstract:A gravitation vortex type water turbine is a water turbine that uses gravitational vortices generated upon water draining from a Tank bottom and can generate power at low head and low flow rate. In our case, given its operation in a free surface flow field, it is critical to quantitatively understand the performance and hydraulic Loss at various flow rates for its design and operation. Accordingly, we investigated the influence of flow rates on the performance of the gravitation vortex type water turbine by conducting experiments and free surface flow analysis. Using the analysis results, we proposed a Loss analysis method and quantitatively evaluated the hydraulic Loss. We found that the effective head and the turbine efficiency increased as the flow rate increased; hence, the turbine output increased at a rate greater than the increase rate of the flow rate. Our study revealed that among the Losses that occurred in the water turbine, the Tank Loss and Tank outlet Loss were the most dominant, followed by the friction Loss inside the Tank, whereas the runner Loss and friction Loss in the runner were small.
Salma Elabd - One of the best experts on this subject based on the ideXlab platform.
-
ISCAS - Analytical and experimental study of tuning range limitation in mm-wave CMOS LC-VCOs
2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013Co-Authors: Salma Elabd, Jamin J. Mccue, Waleed KhalilAbstract:In this paper, we present an analytical model for predicting the tuning range of CMOS mm-wave LC voltage-controlled oscillators (LC-VCOs). A detailed analysis of the frequency dependent quality factor (Q) of the LC-Tank is performed to characterize the Tank Loss. The frequency dependent Q is used to size the transconductance (gm) of the cross-coupled pair to satisfy the VCO startup condition. The relationship between the cross-coupled pair gm and the operating frequency is also derived. With the above relationships, the frequency dependent tuning range is further calculated and compared with simulation results. To verify the analysis, three CMOS mm-wave VCOs are fabricated in a 130 nm CMOS process. The measured tuning range of the 26 GHz, 34 GHz and 40 GHz VCO is 25%, 21% and 18%, respectively, which is consistent with the presented tuning range model.
B. Nauta - One of the best experts on this subject based on the ideXlab platform.
-
A robust 43-GHz VCO in CMOS for OC-768 SONET applications
IEEE Journal of Solid-State Circuits, 2004Co-Authors: A.p. Van Der Wel, S.l.j. Gierkink, R.c. Frye, V. Boccuzzi, B. NautaAbstract:In this paper, we present a 43-GHz LC-VCO in 0.13-μm CMOS for use in SONET OC-768 optical networks. A tuned output buffer is used to provide 1.3 Vp-p (single-ended) into a 90-fF capacitive load as is required when the VCO is used in typical clock and data recovery (CDR) circuits. Phase noise is -90 dBc/Hz at a 1-MHz offset from the carrier; this meets SONET jitter specifications. The design has a tune range of 4.2%. The VCO, including output buffers, consumes 14 mA from a 1-V supply and occupies 0.06 mm2 of die area. Modern CMOS process characteristics and the high center frequency of this design mean that the Tank Loss is not dominated by the integrated inductor, but rather by the Tank capacitance. An area-efficient inductor design that does not require any optimization is used
R.m. Gardner - One of the best experts on this subject based on the ideXlab platform.
-
Effect of load current on leakage flux of transformer with geomagnetically induced current
European Transactions on Electrical Power, 2010Co-Authors: Bing Zhang, L. Liu, Yilu Liu, M. Mcvey, R.m. Gardner, Xiang‐ning XiaoAbstract:Geomagnetic storms caused by solar activity can induce geomagnetic-induced current (GIC) in the power grids. The flow of GIC in the power transformer winding can cause half-cycle saturation of transformer. This saturation can cause distorted exciting current, transformer overheat, and some additional power system problems. There will also be more leakage flux leaving the core and entering into the Tank due to GIC. This will cause large Tank Loss and overheat the transformer. Besides GIC, the leakage flux is also related to the transformer load current. This paper presents a 2D finite-element transformer model. Based on the finite element model, the transformer leakage flux and the Tank Loss caused by GIC with different transformer load current are studied. As a consequence of GIC, the transformer power factor and the magnitude of transformers load current have an important effect on the leakage flux of transformer. Copyright © 2010 John Wiley & Sons, Ltd.
-
Effect of geomagnetically induced current on the Loss of transformer Tank
IET Electric Power Applications, 2010Co-Authors: Bing Zhang, L. Liu, Yilu Liu, M. Mcvey, R.m. GardnerAbstract:Geomagnetically induced current (GIC) can cause half-cycle saturation of transformer. The saturation can increase the stray flux entering into transformer Tank, so the Tank Loss will increase. This study presents a two-dimensional finite element (2D FE) transformer model and the Losses of Tank wall, Tank top and Tank bottom are computed, respectively. Based on the 2D FE magnetic field, the factors that influence the Tank Loss of transformer with GIC are discussed. The influences of magnetic shunt, transformer types, step-up transformer or step-down transformer, and transformer power factor on the Tank Loss are analysed in detail. As a consequence, the transformer types and transformer power factor have large influence on the increase of Tank Loss caused by GIC.
