Showing papers on "Buck converter published in 1992"
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TL;DR: In this paper, the authors describe DC-DC converters by iterated mappings, a nonlinear discrete modeling technique that is applied to the example of a PWM-controlled buck converter.
Abstract: In parameter ranges where conventional methods break down, DC-DC converters may be described by iterated mappings, a nonlinear discrete modeling technique. The underlying principles are explained and are applied to the example of a PWM-controlled buck converter. Stable behavior and bifurcations to chaos are predicted by numerical evaluation of the governing mapping and are confirmed by experiment. >
377 citations
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29 Jun 1992
TL;DR: In this paper, a small-signal analysis is performed for the control scheme of peak current-mode control and the relationship between subharmonic oscillation and the line/load condition of charge control is defined.
Abstract: There are many ways to use the inductor current of a PWM converter as part of its feedback control mechanism. A simple and widely used method is peak current-mode control which uses the instantaneous inductor current as part of the control signals. Charge control is a special type of current-mode control. It uses the integration of the on-time inductor current as the feedback control signal. The characteristics of charge control are studied. A complete small-signal analysis is performed for the control scheme. Subharmonic oscillation similar to that of peak current-mode control is found, and the relationship between subharmonic oscillation and the line/load condition of charge control is defined. Based on the analysis, design guidelines which guarantee the stability of the control system under given line and load ranges are proposed. The small-signal model was confirmed experimentally. >
158 citations
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01 Jan 1992
TL;DR: In this article, a buck converter was proposed, which is composed of rectifier diodes, a small input capacitor, and a buck converter. But the converter's power factor was not shown to be over 0.9 in discontinuous mode.
Abstract: A high-power-factor buck converter is proposed. The converter is composed of rectifier diodes, a small input capacitor, and a buck converter. It supplies low output voltages and uses low voltage semiconductor devices and ceramic capacitors. Two operation modes exist in the converter: discontinuous and continuous inductor current modes. Analysis and experimentation show that the converter's power factor is over 0.9 in discontinuous mode by constant duty ratio operation. It is clarified that the power factor decreases to about 0.7 in continuous mode by constant duty ratio operation, and it can be improved to over 0.9 by a new input current control system. >
150 citations
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29 Jun 1992TL;DR: In this article, a simple and accurate small-signal model for the high-power-factor converter with constant switching frequency is developed and verified, which is applicable to all frequencies below half the switching frequency.
Abstract: A simple and accurate small-signal model for the high-power-factor converter with constant switching frequency is developed and verified. The model is applicable to all frequencies below half the switching frequency. The model is useful in the design and analysis of the voltage and current loops, and of the input and the output impedances of the converter. The use of the model is demonstrated in the analysis and design of a power factor boost converter with average current control. >
122 citations
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TL;DR: In this article, three design criteria for preventing oscillations are derived and interpreted for buck, boost and buck-boost converters, which are summarized in tabular form for the basic buck and boost converters.
Abstract: Addition of an input filter to a current-programmed converter can cause the controller to oscillate. Two instability mechanisms can typically occur: (1) the current programmed controller effective current feedback loop may become unstable, or (2) the controller effective input voltage feedforward loop, which becomes a positive feedback loop when an input filter is added, may oscillate. Three design criteria for preventing oscillations are derived and interpreted. When all three criteria are well satisfied, then the output voltage regulation loop gain is unchanged. Hence, input filters of current programmed converters can be designed in essentially the same manner as for duty-ratio programmed converters. Results are summarized in tabular form for the basic buck, boost, and buck-boost converters. Experimental measurements for a buck converter with different input filters support the theoretical predictions. >
110 citations
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TL;DR: In this article, a simple step-up converter circuit consisting of a single power transistor and an inductor is used as an interface between a PV (photovoltaic) generator and a shunt DC motor driving a centrifugal water pump.
Abstract: A simple step-up converter circuit consisting of a single power transistor and an inductor is used as an interface between a PV (photovoltaic) generator and a shunt DC motor driving a centrifugal water pump. The step-up converter allows maximum power output from the PV generator to the motor at all insolation levels. Steady-state performance of the motor is vastly improved as its input voltage and current are stabilized by the regenerative action of the converter. The PV generator operates at maximum power regardless of insolation variations. The converter duty ratio can be set at a fixed optimal value which is valid for all insolation levels. This remarkable property makes this device economically attractive since it is easy to build and does not require any insolation-dependent control as compared to other peak-power tracking devices. >
91 citations
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23 Feb 1992
TL;DR: In this article, the RMS, DC, and peak currents for five important power factor correctors with capacitive energy storage are presented, and the effect of switched load is taken into account and a simple solution is recommended to reduce that current.
Abstract: The RMS, DC, and peak currents for five important power factor correctors with capacitive energy storage are presented. The correctors are a boost power converter with average current control and hysteretic control, a buck-boost power converter with automatic control, and a buck power converter with pulse width modulation (PWM) sinewave line current and modified sinewave line current. In the calculation of the current in the storage capacitor of the boost corrector with average current control, the effect of switched load is taken into account and a simple solution is recommended to reduce that current. For those correctors where fully sinusoidal line current is not achievable the line harmonics are also determined. >
83 citations
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16 Apr 1992
TL;DR: In this paper, a DC to DC power converter in the form of a pulsewidth modulator is shown which can sense via an indication of duty cycle how much reserve power is available for loads using the present input voltage.
Abstract: A DC to DC power converter in the form of a pulse-width modulator is shown which can sense via an indication of duty cycle how much reserve power is available for loads using the present input voltage. The device is for use at the end of a telephone line where the input voltage power supply impedance can be appreciable. When the reserve power, as detected in the power converter, reaches a minimum critical level, a signal is sent out requesting the voltage supply to increase the available voltage to the power converter.
70 citations
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09 Nov 1992TL;DR: In this article, a simplified MPPT control strategy based on the positive feedback of a maximum power point tracking (MPPT) converter output current was introduced to reduce the energy cost from renewable energy generators by optimizing the utilization of the renewable energy source.
Abstract: A novel simplified control strategy, based on the positive feedback of a maximum power point tracking (MPPT) converter output current, is introduced. Cost-effective MPPT reduces the energy cost from renewable energy generators by optimizing the utilization of the renewable energy source. MPPT for relative small photovoltaic (PV) systems, with battery back-up, is achieved by maximization of the output current to the battery by employing this simplified positive feedback control strategy. This strategy was tested by using a buck converter topology. Experimental verification of the operation of this controller is included. This controller can be utilized in small (one or two panel) as well as larger installations, so that the total MPPT converter cost may be a fraction of the solar panel cost. >
66 citations
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13 Apr 1992TL;DR: In this article, a high-power power supply with a voltage regulator, an inductor, an inverter, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current.
Abstract: A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.
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04 Oct 1992TL;DR: In this article, a novel means of obtaining sinusoidal, unity power factor input currents in switched mode power supplies using minimum additional components is presented, which is topologically equivalent to a boost converter cascaded by a forward power converter, but is realized using only a single power stage.
Abstract: A novel means of obtaining sinusoidal, unity power factor input currents in switched mode power supplies using minimum additional components is presented. The converter is topologically equivalent to a boost converter cascaded by a forward power converter, but is realized using only a single power stage. A detailed analysis of the operation is presented. A constant frequency current mode control provides excellent transient performance at the output and sinusoidal input currents at the input. Various tradeoffs involved in the design of the converter elements and control parameters are discussed in depth. All the results are backed up by experimental waveforms from a laboratory converter. >
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18 May 1992TL;DR: In this article, a systematic method is presented for including parasitic resistances and offset voltage sources of power switches into averaged dynamic large-signal, DC, and small signal circuit models of PWM converters operating in continuous conduction mode.
Abstract: A systematic method is presented for including parasitic resistances and offset voltage sources of power switches into averaged dynamic large-signal, DC, and small-signal circuit models of PWM converters operating in continuous conduction mode. This method is based on the principle of energy conservation. It is shown that the equivalent circuits can be manipulated, using the reflection rule, to simplify the models. A procedure of modeling the buck converter is detailed. Models of all buck-derived converters have the same structure as that for the buck converter, but expressions for averaged components are different. These expressions are given. A design equation for selecting the value of the filter capacitance is derived, and it is shown that the ripple voltage can be made dependent only on the equivalent series resistance of the filter capacitor. >
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06 Feb 1992TL;DR: In this paper, the outputs of the dual-output converter are fully decoupled so as to allow independent control of the ac input current and the power supply output voltage, and the amplitude of the regulated output voltage is controlled by pulse width modulation.
Abstract: An off-line switching power supply includes an ac rectifier and a dual-output switching converter having one output coupled between the ac rectifier and the input to the dual-output converter in order to provide a high power factor, the other output of the dual-output switching converter providing a dc voltage as the power supply output. The outputs of the dual-output converter are fully decoupled so as to allow independent control of the ac input current and the power supply output voltage. In a preferred embodiment, a full-wave ac rectifier bridge is coupled in series with the second output of the power converter via an input resonant boosting converter. A full-bridge dc-to-ac converter is coupled between the dc link and ground for providing an ac signal to excite the boosting converter and for providing another ac voltage through a transformer to an output rectifier to generate a regulated dc output voltage. The amplitude of the regulated output voltage is controlled by pulse width modulation, while active frequency control of the boosting converter is provided to control the amplitude of the ac input current. Alternatively, frequency control of the boosting converter is passive, i.e., depends on the gain characteristics of the boosting converter resonant circuit. As a result of the complete decoupling of the input boosting converter and the power supply output voltage, the off-line switching power supply is capable of drawing high quality current waveforms from the ac source while producing a regulated dc output voltage with fast transient response.
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23 Feb 1992TL;DR: In this paper, a fixed-frequency LCL-type series resonant power converter using an inductive output filter is proposed, which requires a narrow variation in pulsewidth while maintaining a lagging power factor mode of operation for very wide variation in the load.
Abstract: A fixed-frequency LCL-type series resonant power converter which uses an inductive output filter is proposed. Steady-state analysis of the converter is presented using complex AC circuit analysis. Based on the analysis, a simple design procedure is given. Detailed experimental results obtained from a MOSFET-based 500 W converter are presented to verify the analysis. The proposed converter requires a narrow variation in pulse-width while maintaining a lagging power factor mode of operation for very wide variation in the load. >
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17 Jun 1992
TL;DR: In this paper, a switchmode DC-to-AC converter with a master-slave half-bridge converter is described. But the converter is controlled by a lower power self-oscillating master converter (C1, C2, T11, T21).
Abstract: The invention pertains to a switchmode DC to AC converter, and particularly to a master-slave half-bridge converter. The slave half-bridge power converter (C1, C2, T51, T61) is controlled by a lower power self-oscillating half-bridge master converter (C1, C2, T11, T21). More particularly, the invention pertains to a high frequency ballast for gas discharge devices (H), especially, for high pressure sodium lamps (H), completed by a high voltage ignition apparatus (N32, R71, D71, C71, S71, N72, N71).
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25 Nov 1992
TL;DR: In this paper, a power resource management system includes a battery charging system (20) that is connected between a positive voltage terminal and a voltage sense node (15) and a ground terminal (18).
Abstract: A power resource management system includes a battery charging system (20) that is connected between a positive voltage terminal and a voltage sense terminal (15). An operating system (10), that in one mode operates off of the battery and in a second and charging mode operates off the power source (24), is connected between the positive terminal (12) and the voltage sense node (15). A sense resistor (16) is connected between the voltage sense node (15) and a ground terminal (18). The power source (24) is operable to deliver voltage across the positive terminal (12) and the negative terminal (18). The battery charger (20) includes a charge modulator (24) and a buck regulator which has a switch (26) that is controlled by the controller (34). The controller (34) receives the voltage on the node (15) and controls the switch (26) in accordance with the voltage thereon, which voltage is a function of both the current supplied to the operating system ( 10) and the current supplied to the battery (22) for a charging operation. As the operating system current increases, the charge delivered to the battery decreases and, conversely, as the current to the operating system (10) decreases, the current delivered to a battery (22) increases.
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TL;DR: In this paper, the LLC-SRC is derived by adding an inductor in parallel with the resonant capacitor of the conventional series resonant converter, and a set of characteristic curves are derived showing that the control characteristics and component stresses of the new converter are improved compared with those of a conventional SRC.
Abstract: To compensate for the poor output voltage regulation of the series resonant converter (SCR), a converter is derived by adding an inductor in parallel with the resonant capacitor of the conventional SCR. The resulting converter is called the LLC-SRC. This converter is analyzed via a two-dimensional state-plane diagram through a proper transformation of its state variables. Based on the analysis results, a set of characteristic curves is derived showing that the control characteristics and component stresses of the new converter are improved compared with those of a conventional SRC. Based on these curves, the design procedure for the LLC-SRC is formulated. The experimental results from the breadboard model were used to verify the theoretical work. >
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29 Jun 1992TL;DR: In this paper, it is shown that strict current source behavior is unnecessary for good current sharing in parallel-converter systems, and that converters which behave neither as current nor as voltage sources can share a load equally in an a*b array of converters.
Abstract: The origins of the current-sharing problem of parallel-converter systems and the dual problem of voltage sharing in series-converter systems are explored. Both problems are studied by examining the output plane (output current versus output voltage) of a particular converter. It is shown that strict current source behavior is unnecessary for good current sharing in parallel-converter systems, and that converters which behave neither as current nor as voltage sources can share a load equally in an a*b array of converters. One class of converters useful in such systems is that characterized by constant output power (e.g., the clamped series resonant converter). Furthermore, it is shown that constant output power converters are a subset of a broad class of converters whose output voltage is load-dependent, all of which exhibit particular load-sharing good voltage- and current-sharing characteristics. The characteristics of discontinuous mode PWM converters as well as conventional and clamped series resonant converters are examined in detail. A small-signal model of the modular converter system is developed. Experimental results are given. >
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18 Oct 1992TL;DR: In this article, a control scheme for parallel-connected converter systems that will transfer the maximum available power from a nonideal voltage source is presented, which can dynamically regulate the DC-DC converter system to track the peak power point of the source.
Abstract: A control scheme for parallel-connected converter systems that will transfer the maximum available power from a nonideal voltage source is presented. Monitoring the rates of change in both the average input current and the average input power from the source, the proposed control scheme can dynamically regulate the DC-DC converter system to track the peak power point of the source. The amplitude and the frequency of oscillation due to a limit cycle around the system peak power point are analyzed. >
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09 Nov 1992TL;DR: A novel maximum power point tracking (MPPT) converter topology, based on the parallel power conversion technique (PPCT), to enhance the energy conversion efficiency in photovoltaic (PV) systems is analyzed.
Abstract: A novel maximum power point tracking (MPPT) converter topology, based on the parallel power conversion technique (PPCT), to enhance the energy conversion efficiency in photovoltaic (PV) systems is analyzed. Extensive experimental verification of the operation of this converter topology, compared to other topologies, is included. Based on these results, the MPPT topologies are evaluated against each other for utilization in PV systems. The PPCT topology has the highest efficiency compared to the other power converters on the same basis. This increased efficiency is experimentally evaluated and analytically described. It is shown experimentally that the PPCT results in a meaningful enhancement of the basic converter efficiency, from 76% to 94% with a 12 V battery and from 85% to 95% with a 36 V battery. >
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06 Mar 1992TL;DR: A two-stage, Class E, fixed frequency, resonant, DC-to-DC power converter employing phase shift control achieves outstanding performance over a full range from no load to full load.
Abstract: A two-stage, Class E, fixed frequency, resonant, DC-to-DC power converter employing phase-shift control achieves outstanding performance over a full range from no load to full load. Each stage of the DC-to-DC power converter comprises a series inductor-diode network in parallel with a feed choke. Such network is connected between a power source input and a switching transistor, and it provides a fast discharge path for a resonant capacitor and lossless turn-on of the switching transistor in each power converter stage.
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29 Jun 1992
TL;DR: In this article, the authors presented a description and analysis of a new AC/DC converter topology for use in the high-frequency power distribution system in Space Station Freedom, which has close-to-unity rated power factor (greater than 0.98) and low total harmonic distortion in input current (less than 5%).
Abstract: This paper presents a description and analysis of a new AC/DC converter topology for use in the high-frequency power distribution system in Space Station Freedom. Steady-state analysis of the converter is provided, the performance characteristics presented, and transient behavior studied. The proposed converter has close-to-unity rated power factor (greater than 0.98), low total harmonic distortion in input current (less than 5%), and high conversion efficiency (greater than 96%). Finally, to verify the proof of-concept, a bread-board converter was built. >
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29 Jun 1992
TL;DR: In this paper, a buck-type single-ended resonant converter with three-phase rectifier is proposed to automatically draw sinusoidal input currents from a threephase supply.
Abstract: A three-phase rectifier stage, enabling a whole class of switched mode and resonant switched mode power converters to automatically draw sinusoidal input currents from a three-phase supply, is introduced. The proposed technique offers advantages including very simple power circuits, simple control and protection, and very-high-quality input currents. The power factor correction method is described, and the analysis, design, and performance obtained from a buck-type single-ended resonant converter with three-phase supply based on this principle are outlined. Results for a 2.5 kW/40 kHz prototype converter, utilizing a single high-speed GTO as the active switching device and operating directly offline from a 415 V three-phase mains supply, are presented to verify theoretical predictions. The measured input current waveforms drawn from the three-phase supply are sinusoidal with approximately unity power factor. >
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04 Oct 1992TL;DR: In this paper, the authors presented a line-friendly PWM control strategy for DC-link pulse width modulation (PWM) converter with a distortion-free supply network, where the power factor becomes equal to unity under steady-state conditions and the dynamic characteristics of the control system are sufficient.
Abstract: Novel control strategies are presented which use all allowed switching operations of the three-phase voltage DC-link pulse width modulation (PWM) converter such that the converter has a line-friendly performance from the point of view of the utilities or the consumer In the case of an ideal converter and a distortion-free supply network, the power factor becomes equal to unity under steady-state conditions and the dynamic characteristics of the control system are sufficient In order to reach this line friendly performance with an existing converter and to keep the expenditure for the line-side filter low, appropriate PWM at a high switching frequency (>10 kHz) is necessary The theory of the control strategies and appropriate PWM are presented Practical results obtained with an insulated-gate bipolar transistor (IGBT) converter illustrate the dynamic and steady-state performance of the new control system in both energy-flow directions >
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22 Sep 1992
TL;DR: In this article, a three-phase step-up AC/DC power converter with high power factor is proposed, where the AC line currents are independently controlled by means of a transformer secondary with neutral wire and an output capacitor with mid-point connection.
Abstract: A novel three-phase step-up AC/DC power converter with high power factor is proposed. The AC line currents are independently controlled by means of a transformer secondary with neutral wire and an output capacitor with mid-point connection. The transformer whose purpose is separation between the line and the power converter, makes it possible to eliminate in a simple way the high-frequency harmonics. An analysis of the rectifier operations, a mathematical model, the closed-loop control of the output voltage, and numerical simulations are presented.
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12 Mar 1992TL;DR: In this article, a single power converter is used to convert power supplied from an external AC power source to a heating-energy radiator, which then radiates heating energy to the heating chamber.
Abstract: An electric cooking apparatus includes a single power converter section for converting power supplied from an external AC power source. A heating-energy radiator section receives the converted power from the power converter section and radiates heating energy to a heating chamber. A battery is also provided for supplying power to the power converter section such that a sum of the power from the external AC power source and the battery is converted by the power converting section when an instantaneous voltage of the external AC power source is smaller than a predetermined voltage level, which predetermined voltage level is smaller than a maximum instantaneous voltage of the external AC power source.
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25 Feb 1992TL;DR: In this article, a power supply circuit includes a cascade arrangement of a full-wave rectifier and a first and a second switched voltage converter with a switching period which is much shorter than the cycle period of the AC supply voltage.
Abstract: A power supply circuit includes a cascade arrangement of a full-wave rectifier and a first and a second switched voltage converter. The input terminals of the first voltage converter receive a rectified supply voltage. The second switched voltage converter has input terminals connected to a first storage capacitor of the first voltage converter. The second voltage converter includes the output terminals of the power supply circuit. A control circuit controls the period of conductance of the controlled switches of the switched voltage converters with a switching period which is much shorter than the cycle period of the AC supply voltage. A first inductive element is connected via a first controlled switch across the output terminals of the full-wave rectifier during a part of the switching period. A first rectifier diode is connected to the first inductive element so that the diode is non-conducting during this part of the period and, during the period when the diode is conducting, the diode current does not flow to the input terminals of the first switched voltage converter.
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AT&T1
TL;DR: In this paper, a power converter is operative to reduce harmonics at an AC input by controlling its power switching so that a current waveform in a switched inductor is substantially identical to a rectified version of the input AC voltage waveform.
Abstract: A power converter is operative to reduce harmonics at an AC input by controlling its power switching so that a current waveform in a switched inductor is substantially identical to a rectified version of the input AC voltage waveform. The voltage spikes induced by the switching of the inductor into circuitry that includes the leakage inductance of a power transformer are subdued by circuitry that absorbs the initial voltage spike temporarily and then delivers that energy to the output load of the converter.
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29 Jun 1992
TL;DR: In this article, the idea of using coupled inductance in single-phase diode rectifier power factor correction circuits and the influence of the coupling factor on the current ripple are discussed.
Abstract: The idea of using coupled inductance in single-phase diode rectifier power factor correction circuits and the influence of the coupling factor on the current ripple are discussed. The circuit proposed for current shaping consists of a boost converter connected to the line and a buck converter connected to the output capacitor. >