696 results about "Hysteresis comparator" patented technology

High-efficiency envelope tracking (ET) methods and apparatus for dynamically controlling power supplied to radio frequency power amplifiers (RFPAs). An exemplary ET circuit includes a switch-mode converter coupled in parallel with a split-path linear regulator. The switch-mode converter is configured to generally track an input envelope signal Venv and supply the current needs of a load (e.g., an RFPA). The split-path linear regulator compensates for inaccurate envelope tracking by sourcing or sinking current to the load via a main current path. A current sense path connected in parallel with the main current path includes a current sense resistor used by a hysteresis comparator to control the switching of the switch-mode converter. The split-path linear regulator is configured so that current flowing in the current sense path is a lower, scaled version of the current flowing in the main current path.

A power converting device includes a single-phase multiplex converter used as an active filter and a control device. The single-phase multiplex converter includes multiple single-phase inverters connected in series at AC output sides. Each of the single-phase inverters converts DC power fed from a DC power supply into AC power. The control device includes hysteresis comparators and controls output voltage of the single-phase multiplex converter by gradational output voltage control, based on the sum of selectively combined output voltages of the multiple single-phase inverters. The control device controls the single-phase multiplex converter so that an output current follows a harmonic compensation reference currents, canceling harmonics leaking from a load to which the power converting device is connected.

A fast-settling digital automatic gain control circuit comprises first and second gain-controllable amplifiers in series. Each amplifier can be digitally switched between minimum and maximum gains by control logic that receives inputs from a multi-level voltage comparator. A peak detector connected to the output of the first gain-controlled amplifier is used to set the overall operating ranges for several threshold detectors. Four reference voltages are generated from the peak detector. The highest reference voltage is used to clock and reset the gain control logic with a hysteresis comparator to the instantaneous input signal from the first gain-controlled amplifier. The three other lower reference voltages are used to provide three-bits of digital input data to the gain control logic. Two digital controls are output, a min/max gain bit for the first gain-controlled amplifier, and a similar min/max gain bit for the second gain-controlled amplifier.

The invention discloses a rectification control circuit for a bidirectional CLLLC resonant converter. Both the primary side and the secondary side of the transformer in the bidirectional CLLLC resonant converter are connected to a current transformer, and the current on the power receiving side of the transformer is sampled, and It is converted into a voltage signal through a unit resistance, and connected to the inverting input terminals of two hysteresis comparators through a voltage sensor. The output signals of the two hysteresis comparators respectively drive the leading switch and the lagging switch on the power receiving side to realize MOSFET rectification. Since the on-resistance of the MOSFET is very small, the rectification control circuit for the bidirectional CLLLC resonant converter of the present invention reduces the rectification loss and improves the overall efficiency of the converter compared with diode rectification.

In the motor drive apparatus, a Hall element outputs a first sinusoidal signal and a second sinusoidal signal, of mutually opposite phases, in accordance with rotor position. A hysteresis comparator compares the first sinusoidal signal and the second sinusoidal signal outputted from the Hall element, and outputs a rectangular wave signal. A pulse width modulation signal generation circuit detects timing at which phase switches, based on the first sinusoidal signal and the second sinusoidal signal outputted from the Hall element, and outputs a pulse width modulation signal in which duty ratio gradually changes, in a predetermined time-period in which the phase switches. A drive circuit combines the rectangular wave signal and the pulse width modulation signal by a logical operation, and drives the fan motor.

The present invention relates to the field of the driving circuit technology that is a power MOSFET driving circuit. The power MOSFET driving circuit includes a hysteresis comparator, a switch driving stage, an over-current protection circuit module, and the hysteresis comparator compares the externally controlled signals with the reference power level to determine the control signal obtaining the switch drive, and the switch drive stage circuit makes a drive output to the power MOSFET and the drain terminal voltage when the power MOSFET is conductive is induced into the input end of the over-current protection circuit to realize the over-current protection comparing to the standard. The input signal Vin is compared with the standard current Vref through the hysteresis comparator to judges and obtains the logically controlled signal Vol which controls the switch power stage together with the over-current signal Vx to realize over-current protection, and when Vx is a low level and the output level logic of the switch power level is identical to that of the Vol signal. The present invention is adapted to the integrated circuits such as the integrated switch power supply and the control circuit thereof.

The invention discloses a single-input hysteresis comparator circuit, comprising threshold voltage generating loop to generate threshold voltage and positive feedback branch to generate hysteresis voltage, where the positive feedback branch is composed of current source I3 and switch SW connected in series; the threshold voltage generating loop comprises PMOS tubes P1 and P2, NMOS tubes N3 and N4, and current sources I1 and I2; grid of the PMOS tube P1 is used as input end, drain of the PMOS tube P1 is earthed and source of the PMOS tube P1 is connected with source of the NMOS tube N3 and connected to the switch SW and the other end of the switch SW is connected with input end of the current source I3; grid and drain of the NMOS tube N3 are interconnected to grid of the NMOS tube N4 and output end of the current source I1; drain of the NMOS tube N4 is connected with output end of the current source I2, and source of the NMOS tube N4 is connected with that of the PMOS tube P2; grid and drain of the PMOS tube P2 are earthed; input ends of the current sources I1, I2 and I3 are all connected with power supply VDD. And it is designed to detect whether some voltage in a chip is overlow, and it has only one input end to input a voltage to be detected.

The present disclosure illustrates a feedforward controlled envelope modulator and a feedforward control circuit thereof. The feedforward controlled envelope modulator comprises a linear amplifier circuit, a switching amplifier, and a feedforward control circuit. The linear amplifier circuit amplifies an input voltage signal, so as to output an output voltage signal to a load node. The switching amplifier receives a comparison signal, and outputs a switching current to the load node according to the comparison signal. The feedforward control circuit comprises a duplicate linear amplifier circuit and a hysteresis comparator. The duplicate linear amplifier circuit amplifies the input voltage signal, so as to output a reference voltage signal, wherein an amplifying gain of the duplicate linear amplifier circuit is identical to an amplifying gain of the linear amplifier circuit. The hysteresis comparator compares the output voltage signal and the reference voltage signal, so as to output the comparison signal.

The invention relates to a temperature compensation method of a Hall switch based on a CMOS (complementary metal oxide semiconductor) technology and a circuit thereof. The method comprises the following steps: carrying out voltage stabilization and voltage offset on a power supply; and converting Hall voltage signals into single-terminal voltages and eliminating offset voltages as well as comparing processed voltage signals with a set threshold voltage in hysteresis, wherein temperature coefficients of the set threshold voltage are same as temperature coefficients of Hall mobility of a Hall chip. By using the method, temperature coefficients of a threshold voltage of a hysteresis comparator are same as temperature coefficients of electron mobility of a material which is used by the Hall chip, so that the temperature coefficients of the Hall mobility can be offset, thus the Hall switch can work in the temperature range of -40 to 150 DEG C. Compared with the prior art, based on the CMOS technology, fewer components are used in the method, thus the Hall switch can work normally in the wider temperature range.

The invention discloses a rotor-position sensor doubly salient motor system and a control method thereof, belonging to the field of doubly salient motor systems and the control method thereof. The system consists of a doubly salient motor, an excitation winding, a main power circuit and a control circuit, wherein, the main power circuit comprises a power supply and an IPM; and the control circuit comprises an isolation circuit, a failure detection circuit, a three-phase current sampling circuit, an excitation current sampling circuit, a PWM control circuit, an over-current and over-voltage protection circuit, an ADC module, a position detecting circuit, a rotation speed calculation circuit, a logic control circuit, a capture unit, a speed loop, a current loop, a hysteresis comparator and a PI regulator. The control method indirectly controls the current of the doubly salient motor by adopting a dual-loop control type of internal loop for current and external loop for rotation speed and comparing the given rotation speed for reference with the fed practical rotation speed. The method has simple system, firmer structure, reliable operation and high efficiency.

The invention relates to a pulse controller with six PWM (pulse width modulation), which belongs to the technical field of power electronics and automatic control. The PWM pulse controller is composed of a voltage comparator, an inertia link or an integrating link, a hysteresis comparator and the like. The PWM controller, a control object, feedback transformation and the like form a PWM pulse control system, the controlled variable of the control object outputs feedback variable through a feedback transformation link and outputs a pulse signal with control giving through the comparator, a triangle waveform signal is generated through the inertia link or the integrating link, and a PWM pulse control signal is generated through the hysteresis comparator and is acted on the control object to adjust the output variable. When conditions are changed or output pulse acts continuously to enable the feedback variable to deviate from a given target, the PWM controller outputs a pulse control signal, which enables the output of the control object to trace the given target. The PWM controller has simple and reliable structure, low cost, rapid system response, high efficiency and wide application value.

An input voltage is applied to an inverting input terminal of a comparator having no hysteresis. A first constant voltage is divided by resistors to create a reference voltage. The reference voltage is applied to a non-inverting input terminal of the comparator through a resistor. Only while an output voltage of the comparator is a low level, a predetermined constant current is supplied to a supply point of the reference voltage and a constant current of the same magnitude is absorbed from the non-inverting input terminal of the comparator.

The invention relates to a Hall switch circuit with temperature compensation, comprising a voltage stabilizer, a Hall induction sheet, a Hall voltage difference amplifier, a hysteresis comparator and an output unit, wherein the Hall induction sheet is connected between the output and an earth wire of the voltage stabilizer; two input ends of the Hall voltage difference amplifier are respectively connected with the Hall induction sheet; the hysteresis comparator is connected with the output end of the Hall voltage difference amplifier; and the output unit is connected with the input end of the hysteresis comparator. The Hall switch circuit is characterized in that the Hall voltage difference amplifier comprises a difference input pair, a current source and a load resistor, wherein the difference input pair consists of two transistors; the current source offsets the difference input pair and is directly proportional to absolute temperature; and the load resistor is respectively in series connected with the transistors of the difference input pair and is made from materials the same as that of the Hall induction sheet. The Hall switch circuit can eliminate the influence of microhenry temperature coefficient without special requirement for a process and is well controlled.

The invention discloses a high-performance rectifier diode replaced circuit which comprises a capacitor, a low-voltage clock generator, a charge pump circuit, a band-gap reference circuit, a hysteresis comparator, a driving amplifier and a power metal oxide semiconductor (MOS) pipe and is characterized in that the low-voltage clock generator detects voltages at two ends of a diode pipe and generates clock signals to drive the charge pump circuit; the charge pump circuit detects the voltages at two ends of the diode pipe and stores the charges in the capacitor after the charges are amplified; the voltage stored on the capacitor and the standard voltage output by the band-gap reference circuit are respectively output to the hysteresis comparator for comparison; and when the voltage stored in the capacitor is larger than the standard voltage output by the band-gap reference circuit, the hysteresis comparator outputs starting signals which are amplified by the driving amplifier and then output to the power MOS pipe to drive the power MOS pipe to be conducted. The high-performance rectifier diode replaced circuit can achieve equivalent diode working characteristics through a pulse working mode and can totally replace original selective beacon radar (SBR) devices in performance and dimension.

The invention discloses a direct torque control method for a brushless direct current motor. By speed and torque double closed loop control, a rotating speed loop is used as an outer loop, and a torque loop is used as an inner loop; motor speed is calculated according to an output signal of a Hall sensor of the brushless direct current motor, and the motor speed is compared with reference speed to obtain speed error; an output value obtained after fuzzy self-adaptation adjustment is used as a torque expectation value; torque error is obtained by subtracting actual torque from expectation torque, wherein the actual torque is calculated by multiplying back-EMF (Electromotive Force) and phase current; the torque error is inputted into a hysteresis comparator; the hysteresis comparator outputs a position signal of a rotor; and an appropriate voltage vector is selected from a formulated switch list to control an inverter bridge connected with a DC power supply so as to make the brushless direct current motor output stable torque. By the method, the defect that current hysteresis control has a poor effect of inhibiting electromagnetic torque is avoided, and the problem that a traditional PID control method has low precision and poor anti-jamming capability in control of BLDCM is overcome.