Abstract: An embedded bridge rectifier is disclosed. By reconfiguring and reconnecting internal ESD protection circuits originally installed at two bonding pads of integrated circuits, the invention not only saves hardware cost of conventional external bridge rectifiers, but also reduces the space of print circuit boards.

Abstract: Disclosed is a method for operating a transistor as a rectifier element, and a circuit arrangement including a control circuit and a transistor.

Abstract: Disclosed is a synchronous rectification type switching power supply apparatus, including: a transformer that receives input voltage on a primary side; a switching element that is to be turned on or off for rectifying current of a secondary coil of the transformer; a control circuit to drive the switching element. The control circuit includes a first timing detection circuit to detect first timing at which forward current flows through a body diode of the switching element, and a second timing detection circuit to detect second timing with counter electromotive voltage that is generated at an instant when the body diode is turned off. The control unit is to generate an on/off control signal for the switching element to turn on the switching element at the first timing, to turn off the switching element before the second timing and to bring off-timing of the switching element close to the second timing.

Abstract: A method for converting an input voltage signal into an output voltage signal is disclosed. The method includes: providing a primary converting module and coupling the primary converting module to an input port of the voltage converter; providing a secondary converting module having a second electronic induction device and a switch device, coupling the secondary converting module to an output port of the voltage converter, and utilizing the switch device to enable the secondary converting module; measuring a slope of an output at a detection end of the second electronic induction device to generate a slope indication signal having different pulse amplitudes representative of different slope values; and referencing the output at the detection end of the second electronic induction device, the slope indication signal, a first predetermined reference level, and a second predetermined reference level to generate a control signal for controlling an on/off status of the switch device.

Abstract: A primary winding current controlled synchronous rectifying drive circuit including a current sampling circuit that detects a current signal in a primary winding of a transformer and forwards it to a signal shaping and reset circuit, and a current compensation signal circuit that compensates a magnetizing current in the primary winding of the transformer, wherein the signal shaping and reset circuit converts a sample of the current signal into a voltage signal and shapes it into a pulse signal, and then forwards the current signal to a logic control and power drive circuit that converts the pulse signal into one or more drive signal(s) through logic control, then the drive signal(s) are amplified to drive a corresponding synchronous rectifier.

Abstract: An AC-to-DC power converter configured to provide power factor correction and a single isolated low-voltage output. The power converter includes a single-stage resonant power converter including an isolation transformer, a resonant tank, a rectifier, and a bulk storage capacitor coupled to an output of the isolation transformer. In typical applications, at least one non-isolated power converter is coupled to the output of the single-stage isolated power factor correction converter.

Abstract: A current source inverter is disclosed, comprising: means for operating the inverter in fundamental frequency unregulated operation, means for operating the inverter in clocked voltage regulated operation, means for recording parameters from which conclusions can be drawn at an instantaneous operating point and/or at an instantaneous network condition, means for determining an appropriate operating condition from the recorded parameters and means for uninterrupted switching of the operation of the inverter to the operating condition as determined from the recorded parameters and a method for uninterrupted switching of such a current source inverter.

Abstract: In a boost converter including an input transistor receiving an input voltage, an inductor and a main switch serially connected to the input transistor, rectifying means connected to a node between the inductor and the main switch and smoothing means for smoothing the output of the rectifying means to generate an output voltage, a current detection circuit generates a current detection signal corresponding to the current flowing through the input transistor. A voltage detection circuit generates a voltage detection signal corresponding to the output voltage. A startup circuit adjusts the current at the input transistor until the output voltage reaches a first voltage when being lower than the first voltage, and turns ON the input transistor when being higher than the first voltage. A control circuit controls ON/OFF of the main switch based on the current and voltage detection signals so that the output voltage becomes a predetermined value.

Abstract: A primary-side switching circuit generates switching signals for switching a transformer. A secondary-side switching circuit is coupled to an output of the power converter to generate pulse signals in response to the switching signals and an output voltage of the power converter. Pulse signals are generated to rectify and regulate the power converter. A synchronous switch includes a power-switch set and a control circuit. The control circuit receives the pulse signals via capacitors for turning on/off the power-switch set. The power-switch set is connected in between the transformer and the output of the power converter. Furthermore, a flyback switch is operated to freewheel the inductor current of the power converter. The flyback switch is turned on in response to the off state of the power-switch set. The on time of the flyback switch is programmable and correlated to the on time of the power-switch set.

Abstract: A transistor active bridge circuit (100) including first and second field-effect transistors (102, 104) of a first channel type, and third and fourth field-effect transistors (106, 108) of a second channel type that is different from the first channel type. The transistor active bridge circuit also includes a plurality of gate drive circuits for the field-effect transistors. A set of voltage dividers (110/112, 114/116, 118/120, 122/124) and/or voltage clamping devices (126, 128, 130, 132) permit the circuit (100) to efficiently operate over a wider range of input voltages, without potential damage to the gate drive circuits.

Abstract: A cat-ear power supply is operable to generate a DC voltage and draws current from an AC power source near the beginning and end of a half-cycle of the AC power source. A controllably conductive switching circuit selectively charges an energy storage capacitor to produce the DC voltage and become conductive to charge the energy storage capacitor near the beginning of the half-cycle of the AC power source. A latch circuit controls the controllably conductive switching circuit to become non-conductive in response to the magnitude of the DC voltage. A switch voltage monitor circuit controls the controllably conductive switching circuit to become non-conductive and resets the latch circuit when the magnitude of a switch voltage across the switching circuit exceeds a predetermined switch voltage threshold. The switching circuit becomes conductive to charge the energy storage capacitor near the end of the half-cycle when the magnitude of the switch voltage drops below the predetermined switch voltage threshold.

Abstract: A full-wave rectifying device includes a first rectification module and a second rectification module. The first rectification module includes one or a plurality of first rectification units. The second rectification module includes one or a plurality of second rectification units. In each of a plurality of transistors, the substrate is connected to the source so as to reduce the body effect of the rectifying circuit efficiently and enable generation of a dc voltage signal through rectification by a plurality of capacitors. A multistage rectifying circuit architecture including a plurality of first rectification units and second rectification units is provided, so as to reduce the body effect of transistors of a conventional rectifier and significantly stabilize the voltage output level, thereby allowing the rectifying circuit to generate a dc voltage level of designed value.

Abstract: A bridgeless power factor correction converter that can reduce common-mode noise and enhance power density is made up of a boost inductor coupled to an input end, a bidirectional switch connected in series with the boost inductor, a first series rectifying circuit having a junction node connected between the boost inductor and the bi-directional switch, a second series rectifying circuit connected in parallel with the first series rectifying circuit and having a junction node coupled to the bi-directional switch, and an output capacitor connected in parallel with the second series rectifying circuit, in which the second series rectifying circuit is made up of slow-recovery diodes and the first series rectifying circuit is made up of fast-recovery diodes.

Abstract: In a power converting apparatus in which two three-phase converters (1), (2) are operated parallel to one another, the three-phase converters (1), (2) are controlled by using d- and q-axis voltage commands. DC current sensors (26), (27) detect individual output DC currents (26a), (27a) of the three-phase converters (1), (2), and a d-axis voltage command vdr for each of the three-phase converters (1), (2) is corrected in a manner that reduces a difference between the output DC currents (26a), (27a). In this way, an output imbalance between the two three-phase converters (1), (2) is corrected while decreasing limitations on arrangement of the DC current sensors (26), (27).

Abstract: In a double-ended isolated DC-DC converter, by using a main transformer and first and second pulse transformers, a first power switch of a primary side circuit and a first synchronous rectifier of a secondary side circuit are driven with complementary timing, and a second power switch of the primary side circuit and a second synchronous rectifier of the secondary side circuit are driven with complementary timing. A first turn-off edge signal and a first turn-on edge signal generated in a primary side control circuit are transmitted to the secondary side via the first pulse transformer so as to generate a driving signal of the first synchronous rectifier. In addition, a second turn-off edge signal and a second turn-on edge signal generated in a primary side circuit are transmitted to the secondary side via the second pulse transformer so as to generate a driving signal of the second synchronous rectifier.

Abstract: Disclosed is a method for operating a transistor as a rectifier element, and a circuit arrangement including a control circuit and a transistor.

Abstract: A signal processing circuit includes an input inverter and an output inverter. Each inverter has a signal input for receiving an input rectangular signal, a signal output for providing an inverted output rectangular signal, and a pair of voltage outputs for developing a rectified dc output voltage. A first circuit input terminal is connected to the output of the input inverter and the input of the output inverter. A second circuit input terminal is connected to the input of the input inverter and the output of the output inverter, wherein the signal input terminals receive an input signal having a data component. A pair of supply voltage output terminals is connected to the voltage output terminals of the inverters for providing a rectified dc supply voltage output.

Abstract: A rectifier filter control device for a power supply that includes: A saturable inductor (swing choke), capacitors; and rectifiers connected to a rectifier filter circuit. The rectifier filter circuit further includes two electronic switches, which are respectively connected to two terminals of each of the two rectifiers. Should a reverse current flow back into the rectifier filter circuit, then the two electronic switches assume off states at different time sequences, thereby preventing the reverse current flow from burning out the two electronic switches.

Abstract: An apparatus, such as an inverter or rectifier in a double-conversion UPS, includes a plurality of power switching devices, such as IGBTs, coupled in parallel. A drive circuit is coupled to the power switching devices at a plurality of drive nodes and configured to drive the drive nodes responsive to a drive control signal. A monitoring circuit is coupled to the drive circuit and configured to determine respective statuses of respective ones of the power switching devices. The monitoring circuit may be configured to generate respective measures of drive delivered to respective ones of the drive nodes.

Abstract: A synchronous regulation circuit is provided. A secondary-side switching circuit is coupled to the output of the power converter to generate a synchronous signal and a pulse signal in response to an oscillation signal and a feedback signal. An isolation device transfers the synchronous signal from the secondary side to the primary side of the power converter. A primary-side switching circuit receives the synchronous signal to generate a switching signal for soft switching a transformer. The pulse signal is utilized to control a synchronous switch for rectifying and regulating the power converter. The synchronous switch includes a power switch and a control circuit. The control circuit receives the pulse signal for turning on or off the power switch. The power switch is connected between the transformer and the output of the power converter. A flyback switch is operated as a synchronous rectifier to freewheel the inductor current of the power converter.

Abstract: A step-down switching regulator prevents an output voltage undershoot and enables a quick lowering of an output voltage immediately after turning off of power supply. The step-down switching regulator includes an NMOS transistor connected between an output terminal and a ground voltage and another NMOS transistor connected in parallel with a synchronous rectification transistor. Upon reception of an on/off signal for terminating the operation of the switching regulator, the NMOS transistors are turned on into an on-state.

Abstract: A power factor corrected (pfc) ac-dc converter has a modified boost input and a modified buck output. Unlike the prior art boost input, the boost switch returns to the output, not to ground. Unlike the prior art buck output stage, a third switch connects to the input. This allows much of the input current to pass through the converter to the output. There is no input current measurement, but nearly ideal power factor correction is achieved through “natural modulation.” A preferred pfc ac-dc converter uses a variable dc-dc transformer on its output, as a post regulator, to provide dielectric isolation and to provide voltage level shifting. The output of the pfc ac-dc converter has the control characteristics of a buck converter, so it is a natural mate for the variable dc-dc transformer. An ac-dc buck converter is most efficient at its maximum duty cycle. It cannot regulate for a lower input voltage, but it can reduce its duty-cycle to control for higher input voltages.

Abstract: A synchronous rectification circuit for power converters operable under fixed and/or variable frequencies where no current sense circuit or phase-lock circuit are needed is provided. It has a power switch coupled to a transformer for the rectification. A signal-generation circuit is used for generating a control signal in response to a magnetized voltage of the transformer, a demagnetized voltage of the transformer, and a magnetization period of the transformer. The control signal is coupled to turn on the power switch. The enable period of the control signal is correlated to a demagnetization period of the transformer.

Abstract: Methods, systems, and apparatuses for providing power to devices that are part of RFID systems are described. Energy is harvested at portable/mobile devices, stored and conditioned to provide on-going power as needed for various circuits/components. The energy may be generated in a variety of ways, including using a vibratory energy harvesting device, a magnetic energy harvesting device, and an optical energy harvesting devices.

Abstract: A power supply for a computer includes a transformer, a rectifier, a pulse width modulation (PWM) controller, a relay, a power switch, and a battery. The PWM controller includes a voltage terminal and a pulse terminal. The relay includes a switch and an inductance coil. An alternating current (AC) power supply is connected to a primary inductance coil of the transformer via the rectifier. A secondary inductance coil of the transformer provides a standby voltage. A positive voltage terminal of the rectifier is connected to the pulse terminal of the PWM controller via the primary inductance coil of the transformer. The switch is connected between the positive voltage terminal of the rectifier and the voltage terminal of the PWM controller. The inductance coil and the power switch are connected in series between the battery and ground. The power switch is controlled by powering on or off the computer.

Abstract: A power converter has simple coupled inductor circuit process the power and drive the semiconductor switch perfectly to reduce the power loss and eliminate the needs of high circuit complexity controller, improve the conversion efficiency and reduce the component counts to reach low cost and high reliability at one time.

Abstract: A voltage signal rectifier produces a rectified voltage signal from an input offset voltage signal. The voltage signal rectifier includes input offset, output, and reference nodes, two actively controlled current regulation elements (ACCREs), and two controllers. The input offset node is coupled to the input offset voltage signal. The rectified voltage signal is generated onto the output node. The reference node is coupled to a reference voltage for the input offset and rectified voltage signals. The ACCREs are coupled to the input offset node and one of the ACCREs is coupled to the output node. Each controller is configured to control the one of the ACCREs so that the ACCRE coupled to the output node allows current flow through it when the input offset voltage signal is higher than the rectified voltage signal and the other ACCRE is configured to allows current flow through it when the input offset voltage signal is lower than the rectified voltage signal.

Abstract: A voltage stabilizer circuit of forward converter is disclosed to include a transformer, a first switch, a rectifier, an error amplifier, a control circuit, and a driving circuit. The control circuit outputs a regulation signal that controls turn-on time of the first switch, keeping the output of the load voltage at a stable level.

Abstract: The invention relates to a voltage converter comprising a rectification unit and a voltage regulation unit, wherein the input side of the voltage converter can have an AC voltage applied to it, the output side of the voltage converter can have a rectified voltage taken from it, and the voltage regulation unit regulates the power in the voltage converter.

Abstract: A synchronous rectifier drive circuit includes a primary side and a secondary side. The primary side has a first coil winding, a first MOSFET, an auxiliary MOSFET, an auxiliary capacitor, and an input power source. The secondary side has a second coil winding, a DC voltage source, a second MOSFET, a third MOSFET, a fourth MOSFET, a fifth MOSFET, and an inductor. The gate of the second MOSFET is connected with the source of the fourth MOSFET. The gate of the third MOSFET is connected with the source of the fifth MOSFET. The inductor has two ends, one of which is connected with the drain of the third MOSFET. Accordingly, the synchronous rectifier drive circuit can lessen the variation of pulse wave of the drive voltage and refrain the surge voltage to protect the electronic elements.

Abstract: An input voltage Vin is supplied to a first terminal of a control circuit via an inductor connected to outside, and an output capacitor is connected to a second terminal. A switching transistor is provided between the first terminal and ground, and a synchronous rectifier transistor is provided between the first terminal and the second terminal. A first transistor is provided between a back gate of a synchronous rectifier transistor and the first terminal, and a second transistor is provided between the back gate and the second terminal. A switch control unit turns OFF the first transistor and the second transistor at a step-up stop interval; and turns OFF the first transistor and turns ON the second transistor at a step-up operation interval.

Abstract: A DC converter has a transformer with loosely coupled primary and secondary windings, a main switch connected in series with the primary winding of the transformer, and a series circuit connected to ends of one of the primary winding and main switch. The series circuit includes a clamp capacitor and an auxiliary switch. The main and auxiliary switches are alternately turned on/off so that a voltage of the secondary winding of the transformer is synchronously rectified with synchronous rectifiers and is smoothed with smoothing elements, to provide a DC output. The DC converter also includes a tertiary winding provided for the transformer, tightly coupled with the primary winding, and configured to generate a voltage that drives the synchronous rectifiers.

Abstract: In one embodiment, a power converter system includes a first input terminal and a second input terminal operable to connect to an alternating current (AC) power source, and an output terminal at which an output voltage can be provided to a load. A first inductor and a first diode are connected in series between the first input terminal and the output terminal. A second inductor and a second diode are connected in series between the second input terminal and the output terminal. A first switch is connected to the first inductor and the first diode, and a second switch is connected to the second inductor and the second diode. The first switch and the second switch alternately function as a boost switch and a synchronous rectifier for charging and discharging the first and second inductors during operation of the power converter system.

Abstract: An apparatus for synchronous rectifying of a soft switching power converter is provided. An integrated synchronous rectifier includes a power transistor coupled between a transformer and the output of the soft switching power converter, and a controller receiving a pulse signal to switch on/off the power transistor. A switching control circuit generates the pulse signal in response to a current signal, and generates drive signals to switch the transformer in response to a switching signal. An isolation device is coupled to transfer the pulse signal between the switching control circuit and the integrated synchronous rectifier. The switching signal is used for regulating the power converter and the current signal is correlated to the switching current of the transformer.

Abstract: A single-stage power factor correction circuit includes a first rectifier, a second rectifier, a full bridge rectifier, a capacitor, a fly back transformer, and a switch. Unlike conventional single-stage power factor correction circuits, the present invention just needs to pass through two rectifiers at positive and negative half cycles, so as to reduce the conduction loss, lower the temperature of the power supply, and control the voltage of the control energy storage capacitor, and stabilize voltage output.

Abstract: A circuit used to convert a DC input to an AC output comprises a pair of series circuits, one or two capacitors, and one transformer. Each of the series circuits is in parallel with the DC input and comprises a pair of series-connected switches and at least one transformer primary. Each capacitor couples the two series circuits, and is attached to each series circuit at a node between the respective transformer primary and switch. The center nodes between two series-connected switches are connected together. At least one secondary on the transformer provides the AC output. Optionally, multiple transformers may be utilized. Similar topologies may be used for rectification instead of inversion.

Abstract: A method and apparatus for predicting the discharge time of magnetic device are provided. A switching circuit generates a switching signal and an auxiliary signal. The switching signal is used to regulate the switching regulator. The auxiliary signal is used to control the synchronous rectifier. An evaluation circuit generates a timing signal in response to an input signal and the switching signal. The input signal is correlated to the input voltage of the switching regulator. The timing signal is formed for turning off the synchronous rectifier for preventing a reverse current under light load and no load conditions.

Abstract: Industrial truck with a charger, an asynchronous machine and a three-phase AC control unit which converts a DC voltage of a battery for the asynchronous machine, the charger having a switching power supply which is connected to the three-phase AC control unit via a transformer, the switching power supply, the three-phase AC control unit and the transformer forming a resonant converter, which converts a mains voltage into a charging voltage for the battery.

Abstract: A circuit for controlling the operation of synchronous rectifiers. The circuit delays the turn-off of the synchronous rectifiers in accordance with the load current. The magnitude of the load current is examined to determine which of a plurality of delay elements is selected to delay turn-off of the synchronous rectifiers. Delay is accomplished by holding up for a predetermined time period one of a plurality of control signals utilized to determine when the synchronous rectifier should be turned-off.

Abstract: A synchronous rectification and voltage stabilization circuit includes a saturable inductance coil (L1), a synchronous rectifier switch (33), a driving coil (L2) for turning on the synchronous rectifier switch, a discharging coil (L3) which co-operates with a controllable switching component (Q1) to turn off the synchronous rectifier switch, a filter circuit (40) and a voltage stabilization circuit (50). The saturable inductance coil, the synchronous rectifier switch and the filter circuit are connected in serial between an input terminal (10) and an output terminal (20). The saturable inductance coil is coiled together with the driving coil and the discharging coil on one core. The voltage stabilization circuit is connected between the output terminal and the saturable inductance coil, and is used for regulating a regulable saturation point of the saturable inductance coil according to an output voltage of the output terminal and a target value of the output voltage.

Abstract: A device that includes an active rectifier (14) having control gates controllable to produce an output voltage on a DC bus (20), a gate control circuit (16) for producing gate control signals for controlling the active rectifier control gates, a first circuit (18) connected to the gate control circuit (16) and producing a command current magnitude signal and a power factor signal for use by the gate control circuit (16), a current line (30) providing a current related to the DC load current to the first circuit (16), and a voltage line (32) providing a voltage related to the DC bus voltage to the first circuit (16), the first circuit (16) including a peak detector (64) detecting current peaks on the DC bus (20), a command current magnitude signal generator (34) commanding a current as a function of the detected peaks, and a power factor controller (33, 40) varying the power factor signal (42) to control the voltage on the DC bus (20).

Abstract: A method of improving the operation of a synchronous rectifier circuit which includes a switching transistor and synchronous transistor, by providing an operatively effective value of inductance in the current path of the synchronous transistor; which is shared by the control terminal circuit path of the transistor and by selecting a synchronous transistor having a low resistance to a control signal provided at the control terminal, as well as improved synchronous rectifier circuits designed according to the method. When the transistors are MOSFETs, the inductance provided is preferably a purely parasitic common source inductance in the range of about 2 nH to about 3 nH. The synchronous transistor exhibits a low value of gate resistance to facilitate fast energy exchange between the common source inductance and the gate-source capacitance.

Abstract: A method for converting a three-phase AC voltage to a regulated DC voltage using a three-phase rectifier is disclosed. Both the positive and negative DC currents are controlled, but the inner phase is not controlled. In one embodiment, the AC to DC converter utilizes a three-phase rectifier with low-speed diodes, three low-speed bidirectional switches, two high-speed diodes, two high-speed unidirectional switches, three inductors on the AC side, and two capacitors connected in series.

Abstract: A toroid-free ballast comprising a filter and rectifier circuit (10) coupled with an AC power, a switch and resonant circuit (20) coupled with the filter and rectifier circuit (10), characterized in that, the switch and rectifier circuit (20) comprises a half bridge oscillating circuit composed of two transistors. The present invention has the benefits of being toroid-free, as well as being relatively compact in configuration, low in cost and favourable for the miniaturization of the electronic ballast.

Abstract: A synchronous rectifier is arranged to rectify inductively coupled power using FETs (field effect transistors) to minimize the voltage drop of the rectifier, which minimizes power loss. Power loss is an important consideration in applications where fairly significant power is coupled to a device (such as a battery charger or other energy storage device) for a fairly short time (such as less than one hour) at a fairly low voltage (such as around 2.5 to 4.5 volts). Body diodes of the FETs can be used to supply power for bootstrapping and control logic for controlling the FETs.

Abstract: An active diode is disclosed. One embodiment provides a method for operating a device. The electronic device includes a transistor connected between a first and a second connection of the electronic device; a control device coupled to a control connection of the transistor; and an energy storage device coupled to the control device.

Abstract: A variation of a threshold of diode-connected transistors is compensated for to maintain a constant rectification efficiency of a rectifier circuit, thereby enabling stable detection of a start signal. A constant voltage is applied to DC bias terminal of cascaded half-wave voltage doubler rectifier circuits (including MOS transistors M1 to M4 and capacitors C1 to C4) forming a rectifier circuit, and a voltage equal to the sum of the constant voltage applied to DC bias terminal 103 and a variation ?Vt of a threshold voltage of the MOS transistors is applied to DC bias terminal 104 of cascaded half-wave voltage doubler rectifier circuits (including MOS transistors M5 to M8 and capacitors C5 to C8) forming a bias circuit.

Abstract: A DC-to-DC converter having a transformer with a primary and a tapped secondary, two serial output filter inductors connected parallel with the secondary, a center output filter inductor connected between the secondary tap and serial output inductors, two serially connected switches connected in parallel with the two output inductors for receiving a signal to control operation of the switches during steady state and an output load connected between the serial connection of the serial output inductors and serial switching devices. The transformer primary side connected with double-ended primary-side topologies. The transformer secondary and output filers configured to form a current tripler rectifier, current quadtupler rectifier or current N-tuper rectifier.

Abstract: The invention relates to a power converter for converting a first electrical power signal into a second electrical power signal having an output voltage Vout with a DC component comprising a control circuit (320) arranged for measuring the output voltage Vout and controlling the operation of the power converter in dependence thereof. The control circuit (320) comprises voltage level shifting means (326) for generating a measurement voltage signal V2 by adjusting the DC component of the output voltage Vout.

Abstract: A synchronous rectifier circuit and a multi-output power supply device using the same include a semiconductor switch to control a current flow of the synchronous rectifier circuit, and a switching controller to control the semiconductor switch according to a synchronous rectification control signal and an output control signal generated by feeding back the output voltage of the synchronous rectifier circuit. The synchronous rectifier circuit can control an output voltage, decrease power loss so as to increase the efficiency of the synchronous rectifier circuit, and decrease the cost of the synchronous rectifier circuit.