Abstract: An integrated circuit with voltage regulator circuitry is provided. The voltage regulator circuitry may include an adaptive bleeder circuit. The adaptive bleeder circuit may include one or more switchable current leaker paths and an associated bleeder control circuit having current sensing circuitry and voltage comparison circuitry. The current sensing circuitry may monitor the amount of current that is being delivered to a load circuit, whereas the voltage comparison circuitry may output control signals that selectively activate one or more of the current leaker paths depending on the monitored current values. Adaptive bleeder circuit configured in this way can help maintain stability of the voltage regulator while minimizing dynamic power consumption.

Abstract: A switched power converter includes a power stage for generating an output voltage according to a switching signal and an input voltage via a switching element. The switching signal is generated by a variable timing generator which is controlled by a compensator. The pulses of the switching signal are generated on a “need to have basis”. Hence, theses pulses may be generated independently of a PWM period. The pulses can be generated such that switching losses are minimized. A switching pattern can be matched to the load current pattern. Thus, the behavior of the compensator can be synchronized to a regular pattern of the load current. A high resolution variable timing generator may be employed.

Abstract: The extended commutation cell (ECC) is a four-port, four-switch cell that allows for bidirectional energy transport in two orthogonal directions throughout the cell. By cascading multiple cells, a multilevel converter can be constructed with a high number of levels. The voltage across each cell capacitor can be adjusted independently of the load, resulting in high flexibility in output levels. Improved fault tolerance is also provided.

Abstract: A DC-DC converter including an input, an output, a conversion circuit, and a switch control circuit. The input inputs input voltage. The output outputs output voltage. The conversion circuit a plurality of semiconductor switches, and converts the input voltage to the output voltage by switching operation of one or more semiconductor switches of the plurality of semiconductor switches. The switch control circuit selects one or more semiconductor switches performing the switching operation from the plurality of semiconductor switches based on the input voltage and a predetermined lookup table, and controls the switching operation of the one or more semiconductor switches.

Abstract: An apparatus that includes resonant tanks, switches, control logic and one or more non-resonant capacitors. The control logic that generates two or more sets of control signal inputs applied to the inputs of the switches so that for each set of control signals one or more sub-circuit loops are formed, and wherein the one or more sub-circuit loops for a first set of control signals is different from the one or more sub-circuit loops for a second set of control signals, and each of the sub-circuit loops includes one or more of the resonant tanks, and at least one of the sub-circuit loops includes a non-resonant capacitor.

Abstract: A method and a circuit of detecting attachment and detachment between a portable device and a power converter are provided. The method and the circuit confirm attachment of the portable device to the power converter and generate an attachment signal. The method and the circuit further detect a bus voltage of the power converter for confirming detachment of the portable device from the power converter.

Abstract: A switching power converter is configured to control switching noise by implementing a plurality of pulse width modulation modes of operation. The peak current in each pulse width modulation mode of operation is controlled so that an output power for the switching power converter is continuous with regard to transitions between the pulse width modulation modes.

Abstract: Power adapters generally include a few components that make up the majority of the volume. One component that can consume a relatively large volume is a bulk capacitor. In accordance with the implementations described herein, the size (which can include the capacitance value or volume) of the bulk capacitor within a power adapter can be reduced. Moreover, by introducing a new control scheme, the bulk capacitor can be eliminated from the power adapter. This size reduction or elimination of the bulk capacitor from a power adapter can result in not only a smaller power adapter, but can also result in a lower cost for production of the power adapter and/or an improvement in the power factor and/or power efficiency of the power adapter. This type of relatively small adapter can be beneficial from a user experience perspective.

Abstract: A controller of a power converter is described that after switching-on a primary switch of a power converter, detects a voltage that is indicative of a primary current through the primary switch and responsive to determining that the voltage exceeds a direct-current (DC) voltage threshold, switches-off the primary switch. The controller stores a peak value of the voltage while switching-off the primary switch, and responsive to determining that the peak value is higher or lower than a range of target values associated with the peak value of the voltage, the controller adjusts at least one of the DC voltage threshold or the range of target values for a subsequent switching cycle of the primary switch.

Abstract: The present invention relates to a power control apparatus for sub-modules in a Modular Multilevel Converter (MMC), which controls the supply of power to sub-modules in an MMC connected to an HVDC system and to a STATCOM.

Abstract: A control method is used in a switching mode power supply to improve dynamic load response and switching loss. A PWM signal is provided to control a power switch and has a switching frequency. A cross voltage of a transformer in the switching mode power supply is detected to provide a de-magnetization time. The switching frequency is controlled in response to a sleep signal and a compensation voltage, which is generated based on an output voltage of the switching mode power supply. The sleep signal is provided in response to the de-magnetization time and a current sense signal, a representative of a winding current of the transformer. The switching frequency is not less than a first minimum value if the sleep signal is deasserted, and not less than a second minimum value if the sleep signal is asserted. The second minimum value is less than the first minimum value.

Abstract: Energy channelling AC-DC converters, methods, and control systems are provided.

Abstract: A power supply having a primary side and a secondary side is disclosed. The power supply includes a main transformer having a first side and a second side. The first side is coupled to the primary side and the second side coupled to the secondary side. The power supply further includes a primary switch coupled to the first side and a synchronous rectification switch coupled to the second side. A controller is included for driving the primary switch and the synchronous rectification switch in several operation modes including the operation in continuous conduction mode. The controller is configured to determine and set a time between turning-off of the synchronous rectification switch and turning-on of the primary switch based on sampling of the peak voltage at the drain of the synchronous rectification switch and selecting the time that corresponds with the lowest peak voltage on the drain of the synchronous rectification switch.

Abstract: A converter includes a DC input; a transformer including first and second primary windings, first and second secondary windings, and first and second feedback windings; a first field-effect transistor; a second field-effect transistor; and a drive circuit connected to the first and second field-effect transistors. The drive circuit includes a bias circuit that applies a bias voltage to gates of the first and second field-effect transistors via the first and second feedback windings during start-up of the converter, wherein the bias voltage is reduced to zero or substantially zero after start-up of the converter; and a reset circuit that resets the bias circuit when the converter is turned off. The converter is a self-oscillating push-pull DC-DC converter.

Abstract: An arrangement is provided for alternatively providing a 3-phase or a 1-phase power stream. In an embodiment, the arrangement includes a 3-phase power source including a first, a second and a third power source output terminal; a switching section adapted to selectively provide, from the three power source output terminals of the 3-phase power source, either: a 3-phase power stream at three arrangement output terminals or a 1-phase power stream at two arrangement output terminals, different from the three arrangement output terminals.

Abstract: An energy efficient apparatus includes a switching device, a frequency dependent reactive device, and a control element is provided. The switching device is coupled to a source of electrical power and includes a pair of transistors and is adapted to receive a control signal and to produce an alternating current power signal. The frequency of the alternating current power signal is responsive to the control signal. The frequency dependent reactive device is electrically coupled to the pair of transistors for receiving the alternating current power signal and producing an output power signal. The frequency dependent reactive device is chosen to achieve a desired voltage of the output power signal relative to the frequency of the alternating current power signal. The control element senses an actual voltage of the direct current power signal and modifies the control signal delivered to achieve the desired voltage of the direct current power signal.

Abstract: To improve accessibility with respect to a power conversion unit in a power converter. The power converter includes a circuit connection part including a positive electrode conductor, a negative electrode conductor and an AC conductor, a power semiconductor module positioned in a particular direction with respect to the circuit connection part and connected to the positive electrode conductor, the negative electrode conductor and the AC conductor and a capacitor positioned in the particular direction with respect to the circuit connection part and connected to the positive electrode conductor and the negative electrode conductor. The positive electrode conductor is connected to a positive electrode conductor of another power conversion unit through a unit connection part positioned in an opposite direction of the particular direction with respect to the circuit connection part.

Abstract: A reconfigurable converter includes a power circuit receives a direct current (DC) power signal and provides an alternating current (AC) output signal across at least three phases. The power circuit comprises a plurality of legs, each leg comprising an output node. A coupling device provides a first output configuration and a second output configuration for the plurality of legs. In the first output configuration, the coupling device comprises a coupling portion coupling at least two output nodes to provide a common output terminal. In the second output configuration, the coupling device comprises separate output terminals, each connected to one of the at least two output nodes.

Abstract: A grid-tied inverter for supplying current to a power supply system includes an output bridge arrangement that is actuated via a pulse width modulator, wherein switching times of the output bridge arrangement are determined by using a periodic auxiliary signal, wherein the frequency of the periodic auxiliary signal varies according to a prescribed periodic wobble signal. The inverter further includes a synchronization unit configured to provide phase synchronization of the auxiliary signal to the power supply system, wherein the synchronization unit is configured to adjust a prescribed phase offset of the periodic auxiliary signal in relation to a phase of the power supply system, and a further synchronization unit configured to provide phase synchronization of the periodic wobble signal to the power supply system.

Abstract: A driver assembly comprises several semiconductor switches that are arranged in a plane so that distances between adjacent semiconductor switches in the plane are equally large, and so that each semiconductor switch has the same number of adjacent semiconductor switches.

Abstract: A power conversion device is provided which includes a plurality of series circuits each formed of a voltage source and a controlled current source. At least two of said series circuits formed of the voltage source and the controlled current source are connected in parallel. Further, parallel connection points of the series circuits connected in parallel form output terminals.

Abstract: The present invention relates to a wafer (100) being subdivided and separable into a plurality of dies. Each die (110) comprises an array of capacitive micro-machined transducer cells (1). Each cell comprises a substrate (10) comprising a first electrode (11), a membrane (13) comprising a second electrode (14), and a cavity (12) between the substrate (10) and the membrane (13). Each cell (1) of at least a part of the dies (110) comprises a compensating plate (15) on the membrane (13), each compensating plate (15) having a configuration for influencing a bow (h) of the membrane (13). The configurations of the compensating plates (13) vary across the wafer (100). The present invention further relates to a method of manufacturing such a wafer and a method of manufacturing such a die.

Abstract: A driving apparatus according to the present invention includes: a movable part including a vibrator including a piezoelectric element and a pressurization part for bringing the vibrator into pressure contact with a base part by applying impression force to the vibrator, the movable part being linearly driven; and a cover part for receiving reactive force of the impression force through intermediation of a rolling part, the cover part being fixed to the base part by a holding part extending in a direction crossing a movement direction of the movable part, in which the rolling part is sandwiched by a guide part of the movable part extending in the movement direction of the movable part and a cover guide part of the cover part extending in the movement direction of the movable part, and the movable part is positioned on an outer side beyond a side of the holding part facing the movable part.

Abstract: A method for controlling an electric motor includes receiving a first control command that is indicative of a desired motor control. A current operating condition for the motor is determined. It is then determined whether the first control command meets at least one predetermined criterion at the current operating condition. A second control command that is different from the first control command is generated when the first control command meets the at least one predetermined criterion. Generating the second control command includes determining a current value of a motor parameter, changing the parameter value, and using the changed parameter value to generate the second control command. The second control command is then used to control the motor.

Abstract: In order to provide a motor driving circuit in which a portion corresponding to a failed phase can be separated while miniaturization and lower costs are achieved, a motor driving circuit for driving a motor includes: a second driver circuit for driving a driver circuit which supplies a drive current corresponding to one phase of a multiphase motor having three or more phases, to the multiphase motor; and an electrical circuit which includes a plurality of electrical components and switches a connecting relation between the electrical components according to an operation mode designated from outside the motor driving circuit, thereby providing a circuit function corresponding to the operation mode.

Abstract: A control device includes: an induced voltage detection circuit that detects induced voltages which is generated in at least one coil of a brushless DC motor; a rotational position that detects the rotational position of a rotor of the brushless DC motor; an error correct circuit that calculates a first difference between a phase of the induced voltage detected by the induced voltage detection circuit and a phase of the rotational position detected by the rotational position detection circuit; a correction circuit that corrects the detected rotational position based on the first difference and outputs a corrected rotational position signal; and a drive signal generation circuit that adjusts a phase of a drive signal which is supplied to the brushless DC motor based on the corrected rotational position signal and generates the drive signal whose phase has been adjusted.

Abstract: A control circuit controls the operation of a brushless DC (BLDC) sensorless motor having a first terminal connected to a first winding, a second terminal connected to a second winding and a third terminal connected to a third winding. A driver circuit applies drive signals to the first and second terminals and places the third terminal in a high-impedance state. The drive signals include first drive signals at a first current amplitude and second drive signals at a second current amplitude different from the first current amplitude. A differencing circuit senses a first mutual inductance voltage at the third terminal in response to the first drive signals and senses a second mutual inductance voltage at the third terminal in response to the second drive signals. The differencing circuit further determines a difference between the first and second mutual inductance voltages and produces a difference signal that is used for zero-crossing detection and rotor position sensing.

Abstract: The present disclosure relates a motor driving device that includes: an H-bridge circuit that includes first and second legs, each of which has one pair of switches, and supplies a driving current to a motor; a current sensor disposed between the H-bridge circuit and a voltage source; and a controller that acquires a first sensing signal from the current sensor for a first period of time during which a turn-on signal is supplied to a first switch disposed in the first leg or a fourth switch disposed in the second leg, to acquire a second sensing signal from the current sensor for a second period of time during which a turn-on signal is supplied to a second switch disposed in the first leg or a third switch disposed in the second leg, and determines an abnormality in the H-bridge circuit.

Abstract: A method of determining angular position (?) of a rotor of an N-phase permanent magnet motor (PMM). A processor having an associated stored angular position determination (APD) algorithm is programmed to implement the algorithm to cause an associated motor controller to execute steps including forcing one vector at a time a phase vector set of current or voltage vectors to stator terminals of windings for the N-phases a positive and negative magnitude vector, wherein the vector magnitude is sufficiently small to not move the rotor, and a time duration for the forcing current or voltage vectors is essentially constant. The resulting stator current or voltage levels are measured for each current or voltage vector. An N-dimension current vector or voltage vector is generated from superposition of the resulting stator current levels or resulting stator voltage levels. The N-dimension current vector or voltage vector is used to determine angular position.

Abstract: An inverter includes a plurality of inverter legs that each includes first, second, and third switches. A first control line connected to the first switch receives a first control signal. A second control line connected to the second switch receives a second control signal. A third control line connected to the third switch receives the first control signal. The first, second, and third switches are connected sequentially in series. A first connector line is connected between the first switch and the second switch and to a first winding of an electric machine. A second connector line is connected between the second switch and the third switch and to a second winding of the electric machine. The second control signal is complementary to the first control signal.

Abstract: A method and power converter unit for operating a generator includes a rotatable shaft operably coupled with a source of rotational force, a rotor mounted to the rotatable shaft and having at least one rotor pole defining a rotatable direct axis, a stator encircling the rotor and having a set of stator windings, and a power output electrically coupled with the set of stator windings and operable in a power generating mode and a power absorption mode

Abstract: Monitoring thermal conditions of an electric motor using current signals from power supplied to the motor is disclosed herein. The current signals may be used to calculate composite current values which may be used to calculate slip. The slip may be used to provide thermal monitoring and protection to the electric motor. Slip may be calculated using only values from the stator of the electric motor for providing thermal monitoring and protection to electric motors where rotor measurements are not available.

Abstract: A free-standing solar tracker comprises a base, a support frame, a panel assembly comprising one or more solar panels, and an actuator to rotate the panel assembly to track the movement of the sun. The solar tracker is designed to be free-standing and requires no foundation. When the solar tracker is deployed, the base forms a pan to contain a ballast material for holding the base in place. The base of the solar tracker is designed to serve as a “suitcase” to contain most of the components of the solar tracker, making it easier to transport the solar tracker 10 to a location where the solar tracker is installed.

Abstract: A voltage controlled oscillator (VCO) comprising a first supply node, a second supply node, an oscillation transistor, a biasing network, an output node and a feedback network is described. The VCO is be powered by a supply voltage applied across the first and second supply nodes. The oscillation transistor and the biasing network are connected in series between the first supply node and the second supply node. The output node is connected to the oscillation transistor so as to deliver an oscillatory output signal. The feedback network provides an oscillatory feedback signal from the output node to the biasing network. The feedback network comprises a capacitive element and a transmission line connected in series for transferring the feedback signal. The VCO may be integrated in a radar device, for example.

Abstract: A voltage controlled oscillator (VCO), a method of designing a voltage controlled oscillator, and a design structure comprising a semiconductor substrate including a voltage controlled oscillator are disclosed. In one embodiment, the VCO comprises an LC tank circuit for generating an oscillator output at an oscillator frequency, and an oscillator core including cross-coupled semiconductor devices to provide feedback to the tank circuit. The VCO further comprises a supply node, a tail node, and a noise by-pass circuit connected to the supply and tail nodes, in parallel with the tank circuit and the oscillator core. The by-pass circuit forms a low-impedance path at a frequency approximately twice the oscillator frequency to at least partially immunize the oscillator core from external noise and to reduce noise contribution from the cross-coupled semiconductor devices.

Abstract: In a preferred embodiment, the gain expansion in low power mode of a single chain PA is minimized by dynamically adjusting the output impedance of the bias circuit of each gain stage for each mode of operation. Instead of switching in a series attenuator or switching in additional feedback in the first gain stage of a single-chain PA to limit the gain at the increased quiescent current level, this embodiment achieves linear performance by adjusting the quiescent current in each stage to the minimum level that meets the target gain and then increasing the output resistance of the bias circuit of each gain stage in low power mode (LPM) to provide the appropriate level of negative feedback at the base of each amplifying HBT to linearize the gain versus power response.

Abstract: Provided is a power amplification circuit that includes: a first transistor that has an emitter to which a first radio frequency signal is supplied, a base to which a first DC control current or DC control voltage is supplied and a collector that outputs a first output signal that corresponds to the first radio frequency signal; a first amplifier that amplifies the first output signal and outputs a first amplified signal; and a first control circuit that supplies the first DC control current or DC control voltage to the base of the first transistor in order to control output of the first output signal.

Abstract: A Doherty amplifier includes an output combining network that has a first combining network input coupled to a main amplifier path, a lowest-order combining network input coupled to a lowest-order peaking amplifier path, and N?2 additional combining network inputs coupled to other peaking amplifier paths. A final summing node is coupled to the combining network output, and is directly coupled to the first combining network input. N?2 intermediate summing nodes are coupled to the N?2 additional combining network inputs. An offset line is coupled between the lowest-order combining network input and a lowest-order summing node. A longest phase delay imparted by the output combining network on a peaking RF signal between the lowest-order combining network input and the final summing node is greater than all other phase delays imparted on any other RF signal provided to the first combining network input and the N?2 additional combining network inputs.

Abstract: A first amplifier circuit includes differential pair transistors that amplify a difference between input voltages and active load transistors connected to the differential pair transistors. A second amplifier circuit amplifies output voltage of the first amplifier circuit. An offset correction current source is connected in parallel with the active load transistors and adjusts electric current flowing through the differential pair transistors correct offset voltage. An offset correction switch switches a driving state of the offset correction current source. A transconductance proportional current generation circuit generates transconductance proportional current for compensating for temperature drift of offset correction voltage for correcting the offset voltage. The transconductance proportional current is proportional to transconductance.

Abstract: A circuit and method for an audio op-amp that is configured to minimize crossover distortion between push and pull components of the audio op-amp. The audio op-amp includes an input stage that receives differential input signals and generates an output that amplifies the difference between the input signals. The audio op-amp further includes an output stage that receive the amplified signal and generate an audio output signal for playback by a speaker system. The output stage includes a diamond driver circuit that buffers the input stage from the speaker system, a boost circuit that includes a pair of boosting transistors that amplify the current of the amplified signal, and a biasing circuit that provides bias currents to the transistors of the boost circuit in a manner that minimizes crossover distortion between the boosting transistors.

Abstract: A loudspeaker drive circuit uses a dynamic range compressor to implement a non-linear gain function between the input signal to the dynamic range compressor and an output signal from the dynamic range compressor. The output is used to drive a loudspeaker, and the operating parameters of the dynamic range compressor are varied in dependence on a criterion, such as the estimated voice coil temperature, the power consumption or the acoustical distortion.

Abstract: An amplifier includes an input node, an output node, a transistor and a transformer. The input node is configured to receive a first signal. The output node is configured to output an amplified first signal. The transistor includes a first terminal, a second terminal and a third terminal. The first terminal is coupled to the input node and a first supply voltage source. The second terminal is coupled to a second supply voltage source and the output node. The third terminal is coupled to a reference node. The transformer is coupled to the first terminal and the third terminal. The transistor is configured to operate in a sub-threshold region and a near-triode region.

Abstract: A transmitter, a transmission system and a transmission method whereby AM-PM distortions can be compensated with high accuracy without affecting the functions of a predistortor, a ?? modulator and so on. The transmitter includes: a baseband signal generation circuit that outputs the amplitude value and phase value of a baseband signal; a ?? modulation circuit that performs a ?? modulation of the outputted amplitude and phase values to output a pulse signal train; a power supply modulation circuit that supplies, to a pre-stage amplifier, a voltage determined in accordance with the outputted amplitude value; the pre-stage amplifier and a post-stage amplifier that amplify the outputted pulse signal train; and a filter circuit that generates an output signal from the pulse signal train as amplified and outputs the output signal. The power supply modulation circuit determines the voltage for canceling a phase error occurring in the post-stage amplifier.

Abstract: A method for offset calibration may include decoupling a modulator input of a first path from a first stage output, coupling a second path output to the modulator input, applying a common-mode voltage to a second path input, receiving a calibration signal from the modulator output generated in response to the common-mode voltage, and modifying one or more parameters of the modulator to compensate for an offset between the first path and the second path indicated by the calibration signal.

Abstract: Apparatus and methods for a difference amplifier are provided. In certain examples, the difference amplifier can provide high common mode rejection without differential signal attenuation. In an example, a difference amplifier circuit can include first and second amplifiers, first and second buffer amplifiers, a first feedback voltage divider coupled between an output of the first buffer amplifier and an output of the second amplifier, and a second feedback voltage divider coupled between an output of the second buffer amplifier and an output of the first amplifier.

Abstract: An in-line waveguide divider divides power of an incoming high-frequency signal among openings. Amplification boards disposed on a base are provided for respective openings and are each connected in parallel with one another to the in-line waveguide divider. An in-line waveguide combiner includes openings formed correspondingly to the amplification boards, and is connected to the amplification boards. An electrically conductive amplifier cover includes walls formed to provide isolation between circuits of the amplification boards continuously from the in-line waveguide divider to the in-line waveguide combiner, and the entire surface of the amplification boards at the in-line waveguide combiner side is covered with the electrically conductive amplifier cover except openings and openings. Each of the amplification boards includes a waveguide-to-microstrip transition corresponding to the opening, an amplifier element, and a microstrip-to-waveguide transition corresponding to the opening.

Abstract: Disclosed is an amplifier for incremental wattage reduction. The amplifier comprises a first pair of pentode vacuum tubes and a second pair of pentode vacuum tubes arranged in a push-pull-parallel power configuration. Each pentode vacuum tube from the first pair of pentode vacuum tubes and the second pair of pentode vacuum tubes includes a plate element, a screen grid element and a cathode element. The amplifier further comprises a single multi-position user switch to configure the first pair of pentode vacuum tubes and the second pair of pentode vacuum tubes to achieve varying wattage outputs of the amplifier by deactivating at least one of the first pair of pentode vacuum tubes or the second pair of vacuum tubes, and causing at least one of the first pair of pentode vacuum tubes or the second pair of vacuum tubes to operate as triodes.

Abstract: A device and method for controlling the volume of played media through loudspeakers on a golf cart driven by a user with a Bluetooth connected device. A location receiver on the golf cart continuously signals a computing component a signal associated with a location of the golf cart on a golf course. If the golf cart is determined to be located in a volume control area, the volume of sound produced by an amplifier engaged with loudspeakers on the cart is reduced to a predetermined level for that control area. Other control areas can cause the playing of advertisements from the loudspeakers on the cart as it passes into them.

Abstract: Automatic gain control systems disclosed herein can incorporate a confidence metric that can estimate the accuracy of gain adjustments calculated by an automatic gain control module. The confidence metric may be based on a percentage of valid audio samples in a given period of time. Based on the confidence metric, the AGC response may be reduced, delayed, frozen, or otherwise altered from the baseline gain adjustment. Time-averaging process may be used to estimate the input signal power level and determine an appropriate baseline gain adjustment. Additionally, weighting functions can be adjusted to prevent overestimation of the signal power.

Abstract: Apparatus and methods for biasing of power amplifiers are disclosed. In one embodiment, a mobile device includes a transceiver that generates a radio frequency signal and a power amplifier enable signal, a power amplifier that provides amplification to the radio frequency signal and that is biased by a bias signal, and a bias circuit that receives the power amplifier enable signal and generates the bias signal. The bias circuit includes a gain correction circuit that generates a correction current in response to activation of the power amplifier enable signal, and a primary biasing circuit that generates the bias signal based on the correction current and the power amplifier enable signal.