The Experts below are selected from a list of 86247 Experts worldwide ranked by ideXlab platform
Gabriel A Rinconmora - One of the best experts on this subject based on the ideXlab platform.
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a high efficiency wcdma rf power amplifier with adaptive dual mode buck boost Supply and bias current control
IEEE Microwave and Wireless Components Letters, 2007Co-Authors: B Sahu, Gabriel A RinconmoraAbstract:Radio-frequency (RF) power amplifiers (PAs) are often the most power-consuming blocks in portable wireless systems, and maintaining high PA efficiency at heavy and light loads is therefore critical for extended battery life. This letter presents how a 0.5-mum CMOS dynamically adaptive, dual-mode buck-boost power Supply and bias-current control circuit improves PA efficiency. The proposed system is validated with a 1.96-GHz, 25-dBm SiGe heterojunction bipolar transistor (HBT) wideband code division multiple access RF PA, where its Supply voltage and bias current are dynamically adjusted from 0.4 to 4.5 V and 25 to 220mA, respectively, over an output power range of -50 to 25dBm. The prototype system is functional for a 1.8-4.2V Input Supply range, meeting adjacent- and alternate-channel leakage ratio specifications with less than 10% of error vector magnitude across the entire power range. The average efficiency of the dynamically adaptive system (13.67%) was 7times better than the corresponding fixed-supplied, fixed-biased scheme (1.95%), with the same HBT PA
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an accurate low voltage cmos switching power Supply with adaptive on time pulse frequency modulation pfm control
IEEE Transactions on Circuits and Systems, 2007Co-Authors: B Sahu, Gabriel A RinconmoraAbstract:Integrated switching power supplies with multimode control are gaining popularity in state-of-the-art portable applications like cellular phones, personal digital assistants (PDAs), etc., because of their ability to adapt to various loading conditions and therefore achieve high efficiency over a wide load-current range, which is critical for extended battery life. Constant-frequency, pulsewidth modulated (PWM) switching converters, for instance, have poor light-load efficiencies because of higher switching losses while pulse-frequency modulation (PFM) control in discontinuous-conduction mode (DCM) is more efficient at light loads because the switching frequency and associated switching losses are scaled down with load current. This paper presents the design and integrated circuit prototype results of an 83% power efficient 0.5-V 50-mA CMOS PFM buck (step-down) dc-dc converter with a novel adaptive on-time scheme that generates a 27-mV output ripple voltage from a 1.4- to 4.2-V Input Supply (battery-compatible range). The output ripple voltage variation and steady-state accuracy of the proposed Supply was 5 mV (22-27 mV) and 0.6% whereas its constant on-time counterpart was 45 mV (10-55 mV) and 3.6%, respectively. The proposed control scheme provides an accurate power Supply while achieving 2%-10% higher power efficiency than conventional fixed on-time schemes with little circuit complexity added, which is critical during light-loading conditions, where quiescent current plays a pivotal role in determining efficiency and battery-life performance
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a low voltage dynamic noninverting synchronous buck boost converter for portable applications
IEEE Transactions on Power Electronics, 2004Co-Authors: B Sahu, Gabriel A RinconmoraAbstract:With the increasing use of low voltage portable devices and growing requirements of functionalities embedded into such devices, efficient power management techniques are needed for longer battery life. Given the highly variable nature of batteries (e.g., 2.7-4.2 V for Li-ion), systems often require Supply voltages to be both higher and lower than the battery voltage (e.g., power amplifier for CDMA applications), while Supplying significant current, which is most efficiently generated by a noninverting buck-boost switching converter. In this paper, the design and experimental results of a new dynamic, noninverting, synchronous buck-boost converter for low voltage, portable applications is reported. The converter's output voltage is dynamically adjustable (on-the-fly) from 0.4 to 4.0 V, while capable of Supplying a maximum load current of 0.65 A from an Input Supply of 2.4-3.4 V. The worst-case response time of the converter for a 0.4 to 4 V step change in its output voltage (corresponding to a 0.2 to 2 V step at its reference Input) is less than 300 /spl mu/sec and to a load-current step of 0 to 0.5 A is within 200 /spl mu/sec, yielding only a transient error of 40 mV in the output voltage. This paper also presents a nonmathematical, intuitive analysis of the time-averaged, small-signal model of a noninverting buck-boost converter.
Hirofumi Akagi - One of the best experts on this subject based on the ideXlab platform.
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a low speed high torque motor drive using a modular multilevel cascade converter based on triple star bridge cells mmcc tsbc
IEEE Transactions on Industry Applications, 2015Co-Authors: Wataru Kawamura, Kuanliang Chen, Makoto Hagiwara, Hirofumi AkagiAbstract:This paper provides experimental verification of a modular multilevel cascade converter based on triple-star bridge cells (MMCC-TSBC) for a low-speed, high-torque motor drive. The TSBC is one of direct ac-to-ac power converters capable of achieving bidirectional power flow and drawing/feeding three-phase sinusoidal Input (Supply-side) and output (motor-side) currents with any power factor at both sides. This paper designs, constructs, and tests a downscaled drive system combining a 400-V, 15-kW, phase-shifted-carrier PWM TSBC equipped with four bridge cells per cluster and a 320-V, 38-Hz, 6-pole, 15-kW induction motor loaded at the rated torque. Experimental waveforms obtained from the downscaled drive system verify stable operation across a broad range from a standstill to the rated speed, showing satisfactory start-up performance.
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a low speed high torque motor drive using a modular multilevel cascade converter based on triple star bridge cells mmcc tsbc
Ieej Transactions on Industry Applications, 2015Co-Authors: Wataru Kawamura, Makoto Hagiwara, Hirofumi AkagiAbstract:SUMMARY This paper provides an experiment-based discussion on a modular multilevel cascade converter based on triple-star bridge cells (MMCC-TSBC) for a low-speed high-torque motor drive. The TSBC is a direct ac-to-ac power converter capable of achieving bidirectional power flow as well as drawing and feeding three-phase sinusoidal Input (Supply-side) and output (motor-side) currents with any power factor at both sides. This paper discusses active dc-capacitor-voltage control applied to the low-speed, high-torque motor drive. A specially designed downscaled system combining a 320-V, 38-Hz, 6-pole, 15-kW induction motor with a 400-V, 15-kW TSBC is constructed and tested to confirm the validity of the motor drive. Experimental waveforms obtained from the downscaled system confirm stable operation with the rated load torque across a range from a standstill to the rated speed, including satisfactory start-up performance.
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experimental verification of a modular multilevel cascade converter based on triple star bridge cells mmcc tsbc for motor drives
IEEE International Future Energy Electronics Conference, 2013Co-Authors: Wataru Kawamura, Makoto Hagiwara, Hirofumi AkagiAbstract:This paper presents the modular multilevel cascade converter based on triple-star bridge-cells (MMCC-TSBC) with a focus on experimental verification for motor drives. The TSBC is one of the direct ac-to-ac power converters, which is characterized by achieving bidirectional power flow, drawing and feeding three-phase sinusoidal Input (Supply-side) and output (motor-side) currents with any power factor at both sides. Therefore, it is suitable especially for a low-speed, high-torque application of a medium-voltage high-power motor drive requiring regenerative braking. A downscaled system rated at 400 V and 15 kW is designed, constructed, and tested to confirm the validity and effectiveness of the motor drive. Experimental results show that stable operation is verified at such a low speed as 60 min-1 with the rated torque. In addition, it is verified that the motor loaded the rated torque can start up from a standstill without producing any overvoltage or overcurrent.
B Sahu - One of the best experts on this subject based on the ideXlab platform.
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a high efficiency wcdma rf power amplifier with adaptive dual mode buck boost Supply and bias current control
IEEE Microwave and Wireless Components Letters, 2007Co-Authors: B Sahu, Gabriel A RinconmoraAbstract:Radio-frequency (RF) power amplifiers (PAs) are often the most power-consuming blocks in portable wireless systems, and maintaining high PA efficiency at heavy and light loads is therefore critical for extended battery life. This letter presents how a 0.5-mum CMOS dynamically adaptive, dual-mode buck-boost power Supply and bias-current control circuit improves PA efficiency. The proposed system is validated with a 1.96-GHz, 25-dBm SiGe heterojunction bipolar transistor (HBT) wideband code division multiple access RF PA, where its Supply voltage and bias current are dynamically adjusted from 0.4 to 4.5 V and 25 to 220mA, respectively, over an output power range of -50 to 25dBm. The prototype system is functional for a 1.8-4.2V Input Supply range, meeting adjacent- and alternate-channel leakage ratio specifications with less than 10% of error vector magnitude across the entire power range. The average efficiency of the dynamically adaptive system (13.67%) was 7times better than the corresponding fixed-supplied, fixed-biased scheme (1.95%), with the same HBT PA
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an accurate low voltage cmos switching power Supply with adaptive on time pulse frequency modulation pfm control
IEEE Transactions on Circuits and Systems, 2007Co-Authors: B Sahu, Gabriel A RinconmoraAbstract:Integrated switching power supplies with multimode control are gaining popularity in state-of-the-art portable applications like cellular phones, personal digital assistants (PDAs), etc., because of their ability to adapt to various loading conditions and therefore achieve high efficiency over a wide load-current range, which is critical for extended battery life. Constant-frequency, pulsewidth modulated (PWM) switching converters, for instance, have poor light-load efficiencies because of higher switching losses while pulse-frequency modulation (PFM) control in discontinuous-conduction mode (DCM) is more efficient at light loads because the switching frequency and associated switching losses are scaled down with load current. This paper presents the design and integrated circuit prototype results of an 83% power efficient 0.5-V 50-mA CMOS PFM buck (step-down) dc-dc converter with a novel adaptive on-time scheme that generates a 27-mV output ripple voltage from a 1.4- to 4.2-V Input Supply (battery-compatible range). The output ripple voltage variation and steady-state accuracy of the proposed Supply was 5 mV (22-27 mV) and 0.6% whereas its constant on-time counterpart was 45 mV (10-55 mV) and 3.6%, respectively. The proposed control scheme provides an accurate power Supply while achieving 2%-10% higher power efficiency than conventional fixed on-time schemes with little circuit complexity added, which is critical during light-loading conditions, where quiescent current plays a pivotal role in determining efficiency and battery-life performance
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a low voltage dynamic noninverting synchronous buck boost converter for portable applications
IEEE Transactions on Power Electronics, 2004Co-Authors: B Sahu, Gabriel A RinconmoraAbstract:With the increasing use of low voltage portable devices and growing requirements of functionalities embedded into such devices, efficient power management techniques are needed for longer battery life. Given the highly variable nature of batteries (e.g., 2.7-4.2 V for Li-ion), systems often require Supply voltages to be both higher and lower than the battery voltage (e.g., power amplifier for CDMA applications), while Supplying significant current, which is most efficiently generated by a noninverting buck-boost switching converter. In this paper, the design and experimental results of a new dynamic, noninverting, synchronous buck-boost converter for low voltage, portable applications is reported. The converter's output voltage is dynamically adjustable (on-the-fly) from 0.4 to 4.0 V, while capable of Supplying a maximum load current of 0.65 A from an Input Supply of 2.4-3.4 V. The worst-case response time of the converter for a 0.4 to 4 V step change in its output voltage (corresponding to a 0.2 to 2 V step at its reference Input) is less than 300 /spl mu/sec and to a load-current step of 0 to 0.5 A is within 200 /spl mu/sec, yielding only a transient error of 40 mV in the output voltage. This paper also presents a nonmathematical, intuitive analysis of the time-averaged, small-signal model of a noninverting buck-boost converter.
S.g. Narendra - One of the best experts on this subject based on the ideXlab platform.
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Cascode buffer for monolithic voltage conversion operating at high Input Supply voltages
2005 IEEE International Symposium on Circuits and Systems, 2005Co-Authors: V. Kursun, G. Schrom, V.k. De, E.g. Friedman, S.g. NarendraAbstract:A high-to-low switching DC-DC converter that operates at Input Supply voltages up to twice the maximum voltage permitted in a nanometer CMOS technology is proposed. The circuit technique is based on a cascode bridge that maintains the steady-state voltage differences among the terminals of all of the transistors within a range imposed by a specific fabrication technology. The proposed circuit technique permits the full integration of active and passive devices of a switching DC-DC converter with a high voltage conversion ratio in a standard low voltage CMOS process. An efficiency of 87.8% is achieved for 3.6 V to 0.9 V conversion, assuming a 0.18 /spl mu/m CMOS technology. The DC-DC converter operates at a switching frequency of 97 MHz while Supplying a DC current of 250 mA to the load.
Guyeon Wei - One of the best experts on this subject based on the ideXlab platform.
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a fully integrated 3 level dc dc converter for nanosecond scale dvfs
IEEE Journal of Solid-state Circuits, 2012Co-Authors: Wonyoung Kim, David Brooks, Guyeon WeiAbstract:On-chip DC-DC converters have the potential to offer fine-grain power management in modern chip-multiprocessors. This paper presents a fully integrated 3-level DC-DC converter, a hybrid of buck and switched-capacitor converters, implemented in 130 nm CMOS technology. The 3-level converter enables smaller inductors (1 nH) than a buck, while generating a wide range of output voltages compared to a 1/2 mode switched-capacitor converter. The test-chip prototype delivers up to 0.85 A load current while generating output voltages from 0.4 to 1.4 V from a 2.4 V Input Supply. It achieves 77% peak efficiency at power density of 0.1 W/mm2 and 63% efficiency at maximum power density of 0.3 W/mm2. The converter scales output voltage from 0.4 V to 1.4 V (or vice-versa) within 20 ns at a constant 450 mA load current. A shunt regulator reduces peak-to-peak voltage noise from 0.27 V to 0.19 V under pseudo-randomly fluctuating load currents. Using simulations across a wide range of design parameters, the paper compares conversion efficiencies of the 3-level, buck and switched-capacitor converters.
