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ABSTRACT: The class-E zero-voltage switching/zero-derivative switching operation within class-DE amplifiers can be easily achieved by adding external shunt capacitances. This paper gives the analytical expressions for the designs of the class-DE amplifiers with the shunt capacitances composed of linear and nonlinear capacitances for any grading coefficient m of MOSFET body junction diodes at the switch-on duty ratio D=0.25 . In the analysis, an equivalent linear shunt capacitance of the nonlinear MOSFET drain-source parasitic capacitances is derived. Analytical results show good agreements with the simulation and experimental ones, which validate our analysis.
Circuits and Systems I: Regular Papers, IEEE Transactions on 10/2010; · 1.97 Impact Factor
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ABSTRACT: Power efficiency of a class E RF power amplifier versus dc supply voltage V<sub>DD</sub> when the shunt capacitance of the class E amplifier is a nonlinear capacitance with the grading coefficient m = 0.5 is obtained. In the calculation of power efficiency, switching loss due to non-zero turning on of the MOSFET, power loss due to forward voltage drop of the MOSFET body diode, and power loss due to MOSFET on-resistance are incorporated. It is found that the highest power efficiency is obtained at a lower dc supply voltage than the designed dc supply voltage, even though the circuit was designed to achieve the nominal operation at the designed dc supply voltage. The calculation was performed with Mathcad programming and the results were verified with Pspice simulations.
Circuits and Systems (ISCAS), Proceedings of 2010 IEEE International Symposium on; 07/2010
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ABSTRACT: In this paper, we present analytical expressions for the waveforms and design equations for achieving the ZVS/ZDS conditions in the class-E power amplifier, taking into account the gate-to-drain parasitic capacitance of the MOSFET. We also give a design example along with PSpice simulation and experimental results. The voltage waveforms obtained from both the PSpice simulation and the circuit experiment achieved the class-E ZVS/ZDS conditions completely, which verify the analytical expressions. The results in this paper indicate that it is important to consider the effect of the MOSFET gate-to-drain capacitance for achieving the class E ZVS/ZDS conditions. The experimental power conversion efficiency achieved 92.8 % at output power P<sub>o</sub> = 4.06 W and operating frequency f = 7 MHz.
Circuits and Systems (ISCAS), Proceedings of 2010 IEEE International Symposium on; 07/2010
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ABSTRACT: In this paper, equations for waveforms and design relationships are derived for class DE amplifiers with nonlinear shunt capacitances. Using the analytical waveform equations, it is shown that the nonlinearity of the shunt capacitances affects the waveforms only during the dead-time intervals. Additionally, the waveforms with nonlinear and linear shunt capacitances are not very different if class E zero-voltage switching/zero-derivative switching conditions are satisfied. The operation of a class DE amplifier has two dead-time intervals in one period. The switch-voltage waveforms for both dead-time intervals exhibit symmetry. Therefore, the nonlinearity does not have any effect on the series-resonant-circuit elements. As a result, analytical design equations indicate that the series-resonant-circuit elements are independent of the nonlinearity of the shunt capacitances when the supply voltage and the output power are given as design specifications, which is an important result of this paper. The validity of our analysis is confirmed by PSpice simulations and the circuit experiment.
Circuits and Systems I: Regular Papers, IEEE Transactions on 11/2009; · 1.97 Impact Factor
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ABSTRACT: This paper presents expressions for the limiting value of the duty cycle and the minimum value of the slope compensation for marginally stable operation as well as for the normalized crossover frequency, the maximum duty cycle, and the value of the slope compensation at a required phase margin. These quantities describe the performance of the inner-current loop in peak current-mode controlled PWM dc-dc converters. The derivations are based on the Pade approximation of z = exp(sT<sub>s</sub>). The results of this paper can be used for the design of the inner-current loop with a specified phase margin.
Circuits and Systems, 2009. ISCAS 2009. IEEE International Symposium on; 06/2009
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ABSTRACT: A dynamic response of the output voltage to the input supply voltage V<sub>DD</sub> of a class E amplifier is derived with modeling the circuit by a low-frequency model and a high-frequency model. If the perturbation frequency is much lower than the switching frequency, the state-space averaging model of the class E amplifier can be approximated as a single-pole low-pass filter composed of the choke inductance L<sub>RFC</sub> and the parallel combination of the switch resistance and the shunt capacitor resistance. The analysis in this paper is based on the steady-state behavior outside the designed conditions given in. Hence, the derivation is applicable even if the class E amplifier is operated in off-tuned conditions. The analytical results for the frequency response of a 1 MHz class E amplifier matched well with Pspice simulations at the perturbation frequency less than 100 kHz.
Circuits and Systems, 2009. ISCAS 2009. IEEE International Symposium on; 06/2009
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ABSTRACT: The class-E ZVS/ZDS operation within the class-DE amplifier can be easily achieved by adding external shunt capacitances. This paper presents the analytical expressions for the design of the class-DE amplifier with the shunt capacitances composed of the linear and nonlinear capacitances for the switch-on duty ratio D=0.25. In the analysis, an equivalent linear shunt capacitance of nonlinear MOSFET output capacitance are defined and derived. The analytical results show good agreement with the experimental ones, which validates our analysis.
Circuits and Systems, 2009. ISCAS 2009. IEEE International Symposium on; 06/2009
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ABSTRACT: This paper shows that the maximum operating frequency of the class-E power amplifier depends on the transistor duty ratio. The maximum operating frequency increases as the duty ratio decreases under zero-voltage switching and zero-derivative switching conditions at fixed values of the output power, dc supply voltage, and shunt capacitance.
Circuits and Systems II: Express Briefs, IEEE Transactions on 09/2008; · 1.41 Impact Factor
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ABSTRACT: Performance of silicon carbide (SiC) Schottky diodes driven by large-signal square wave voltage is evaluated. The voltage equations for the turn-on and turn-off transitions of the diode are derived assuming a linear junction capacitance, C<sub>j</sub>. The turn-on and turn-off transition voltage waveforms are verified practically for a square wave pulsating between positive 10 V and negative 10 V. The diode current waveforms for 100 kHz, 1 MHz, 2 MHz and 3 MHz are analyzed and presented. For the experiment, CSD10060, 600 V, 10 A Cree SiC Schottky diode is used. The theoretical and experimental results were in good agreement. PSPICE simulation results comparing the performance of CSD10060, MUR1560, 600 V, 10 A ultra fast recovery silicon (Si) junction diode and MSR860, 600 V, 8 A soft recovery Si junction diode is presented.
Circuits and Systems, 2007. MWSCAS 2007. 50th Midwest Symposium on; 09/2007
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ABSTRACT: Design equations for satisfying the suboptimum operating condition, i.e., only the zero-voltage switching (ZVS) condition, of a class-E amplifier with a linear shunt capacitance at any duty ratio are derived. By exploiting the suboptimum class-E operation, various amplifier parameters such as operating frequency, output power, load resistance, and component values can vary, while the ZVS operation and high efficiency can be achieved. An example of a design procedure of the class-E amplifier is given. The theoretical results were verified with PSpice simulation and an experiment.
Circuits and Systems I: Regular Papers, IEEE Transactions on 07/2007; · 1.97 Impact Factor
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ABSTRACT: Due to the nonlinearity of shunt capacitance of the class E amplifier, the output amplitude of the class E amplifier is not a linear function of the DC supply voltage of the class E amplifier. Estimating this nonlinearity is important to maintain ZVS operation in a situation of variable DC supply voltage, e.g., for a amplitude modulated (AM) power amplifier. However, there are no research results for the output amplitude of class E amplifier with nonlinear shunt capacitance. In this paper, the circuit behavior of the class E amplifier with nonlinear shunt capacitance outside designed nominal conditions is obtained using mathematical processing software MathCAD
Circuits and Systems, 2007. ISCAS 2007. IEEE International Symposium on; 06/2007
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ABSTRACT: In this paper, an electronic ballast based on the class E oscillator with a capacitive impedance inverter is presented. The ballast allows us to supply an instant-start fluorescent lamp from a 12-V dc power source. The class E oscillator allows us to increase efficiency using a simple structure with only one switch without a driving circuit. Due to the anti-parallel diode integrated into switch, the zero voltage switching conditions are fulfilled in the ignition mode, maintaining high efficiency. One of the applications of the ballast is in mobile equipment, where compact independent power sources are used, for example, batteries or solar cells. The ballast was designed with the following parameters: V<sub>DD</sub>= 12V, P<sub>o </sub>= 18W, f<sub>o</sub>= 440kHz. The measured efficiency was 83%, the output power was 18.5W, and the dc power was 22.3W at the operating frequency of 444.44kHz
IEEE Transactions on Power Electronics 06/2007; · 4.65 Impact Factor
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ABSTRACT: Design equations for satisfying the off-nominal operating condition [i.e., only the zero-voltage switching (ZVS) condition] of the Class-E amplifier with a linear shunt capacitance at a duty ratio D=0.5 are derived. A new parameter s (V/s), called the slope of switch voltage when the switch turns on is introduced to obtain an image of the distance from the nominal conditions. By examining off-nominal Class-E operation degree of the design freedom of the Class-E amplifier increases by one. In addition various amplifier parameters such as operating frequency, output power, and load resistance range can be set as design specifications. For example, the peak switch voltage and switch current can be taken into account in the design procedure. Examples of a design procedure of the Class-E amplifier for off-nominal operation are given. The theoretical results were verified with PSpice simulation and experiments.
Circuits and Systems I: Regular Papers, IEEE Transactions on 08/2006; · 1.97 Impact Factor
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ABSTRACT: A 12.5-mW dc-dc resonant converter with a 500 MHz class DE power inverter and class E synchronous rectifier was designed and simulated on a 1.2 mum CMOS process chip. A 20 nH spiral inductor was used in the resonant circuit. The class DE inverter requires lower inductance than the PWM buck converter. Soft switching operation enables high conversion efficiency at high operating frequencies. The class DE inverter is a good candidate for on-chip switching converters because of very high efficiency, smaller passive elements, and low peak switch voltage
Power Electronics Specialists Conference, 2006. PESC '06. 37th IEEE; 07/2006
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ABSTRACT: In this paper, approximate and exact analyses of the Class-E oscillator in the injection-locked mode are given. The synchronization band of the oscillation frequency is also studied. Various factors that influence the synchronization band of the injection-locked Class-E oscillator are described. Two methods of injecting a synchronization signal to the Class-E oscillator are proposed by a resistor or by a transformer. They are experimentally verified
Circuits and Systems I: Regular Papers, IEEE Transactions on 07/2006; · 1.97 Impact Factor
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ABSTRACT: A 12.5 mW, 500 MHz class DE power inverter was designed and simulated as an inverter part of dc-dc converters to realize a fully integrated switching power supply using a 1.2 mum CMOS process. A 20 nH spiral inductor was used in the resonant circuit. The class DE inverter requires lower inductance than PWM buck converter. Soft switching operation enables high conversion efficiency at high operating frequencies. The class DE inverter can be an excellent candidate for on-chip switching converters because of very high efficiency, smaller passive elements, and low peak switch voltage
Circuits and Systems, 2006. ISCAS 2006. Proceedings. 2006 IEEE International Symposium on; 06/2006
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ABSTRACT: A near-field evanescent microwave microscope is based on a λ/4 coaxial TEM transmission-line resonator with a silver-plated tungsten tip extending through an end-wall aperture. This microwave microscope is used to characterize local electromagnetic properties of dielectrics, conductors, and superconductors. The resolution of the probe is verified experimentally by scanning etched gold lines on a sapphire substrate. A first-order sensitivity estimation generated from a unified equivalent circuit model of the probe and sample is investigated. The sensitivity inherent to the resonant probe and system noise is discussed. Experimental validation of sensitivity is given.
IEEE Transactions on Microwave Theory and Techniques 03/2006; · 1.85 Impact Factor
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ABSTRACT: A new transfer function from control voltage to duty cycle, the closed-current loop, which captures the natural sampling effect is used to design a controller for the voltage-loop of a pulsewidth modulated (PWM) dc-dc converter operating in continuous-conduction mode (CCM) with peak current-mode control (PCM). This paper derives the voltage loop gain and the closed-loop transfer function from reference voltage to output voltage. The closed-loop transfer function from the input voltage to the output voltage, or the closed-loop audio-susceptibility is derived. The closed-loop transfer function from output current to output voltage, or the closed loop output impedance is also derived. The derivation is performed using an averaged small-signal model of the example boost converter for CCM. Experimental verification is presented. The theoretical and experimental results were in good agreement, confirming the validity of the transfer functions derived.
Circuits and Systems I: Regular Papers, IEEE Transactions on 02/2006; · 1.97 Impact Factor
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ABSTRACT: A single-stage high-power-factor electronic ballast with a Class-E rectifier as a power-factor corrector is proposed. A Class-E rectifier is inserted between the front-end bridge rectifier and the bulk filter capacitor to increase the conduction angle of the bridge-rectifier diode current for obtaining low line-current harmonics. The Class-E rectifier is driven by a high-frequency sinusoidal current source, which is obtained from the square-wave output voltage of the Class-D inverter through an LC series resonant circuit. A high-frequency transformer is used for impedance matching. The experimental results for a 32-W prototype ballast are given. The switching frequency was 61.3 kHz. At full power, the power factor was 0.992 and the total ballast efficiency was 88.3%. The lamp-current crest factor was about 1.36. The simulated and experimental results were in very good agreement.
Circuits and Systems I: Regular Papers, IEEE Transactions on 02/2006; · 1.97 Impact Factor
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ABSTRACT: A new application of power source element in power factor correction is proposed. The power source is inserted between the bridge rectifier diodes and a large bulk capacitor to increase the conduction angle of the rectifier diodes. The power from the DC bus is transferred to power the source via a loss free resistor connected with the DC bus. Analysis, design example, control scheme, and simulation results are given in this paper.
TENCON 2005 2005 IEEE Region 10; 12/2005
