Abstract: One aspect of the present invention includes a reference current generator circuit. The circuit includes a bias circuit configured to generate a reference current along a first current path and a second current along a second current path. The reference current and the second current can be proportional. The circuit also includes a first pair of transistors connected in series and configured to conduct the reference current in the first current path. The circuit further includes a second pair of transistors connected in series and configured to conduct the second current in the second current path. The second pair of transistors can be coupled to the first pair of transistors to provide a collective resistance value of the second pair of transistors that is proportional to temperature.

Abstract: A power supply circuit includes an output driver transistor, a buffer circuit, and an error amplification circuit. The buffer circuit includes a first transistor connected to an output terminal and a second transistor functioning as a load for the first transistor. The error amplification circuit includes a differential pair including a first pair of transistors, a current mirror circuit including a second pair of transistors, a constant current source supplying a current and driving the differential pair and the current mirror circuit, a third transistor connected between one of the differential pair and the current mirror circuit. The first and second transistor have the same polarity as the transistors constituting the current mirror circuit, and control terminals of the first and third transistors are connected at a first junction node that is connected to a second junction node between the one of the differential pair and the third transistor.

Abstract: A beta enhancement circuit includes a current source connected in series with a transistor between two voltage supply lines. In an embodiment, the voltage supply lines are configured for connection to a power source and ground potential. A resistor device is connected between a control terminal of the transistor device and one of voltage supply lines. A value for the resistor device is selected based on one or more process dependent parameters of the transistor.

Abstract: Provided are a reference current generation circuit and a reference voltage generation circuit, which have improved response speed when power supply is activated or fluctuates. In order to reduce a load capacitance of an operational amplifier, a transistor for providing a current to a transistor pair having a common gate-source voltage is provided, and the operational amplifier controls an ON-state resistance of the transistor.

Abstract: A constant voltage circuit includes an output control transistor to control an output current from an output terminal to keep an output voltage constant at a set voltage; and an excess-current protection circuit to control the output control transistor. The excess-current protection circuit includes a current increase restriction element to restrict increase in the output current to decrease the output voltage; a first current limitation circuit to limit a gate voltage of the output control transistor to decrease the output current, when the output voltage is decreased to a first limited voltage; a second current limitation circuit to limit a gate voltage of the output control transistor to decrease the output current, when the output voltage is decreased to a second limited voltage smaller than the first limited voltage; and a selector to select whether the first current limitation circuit is operated or stopped.

Abstract: A reference voltage generation circuit includes a current source configured to generate a current by compensating for an internal temperature change, and output the generated current to an output node where a reference voltage is generated, and a resistor unit coupled to the output node and having a resistance value controlled in response to a control signal generated in a test mode.

Abstract: A reference voltage generation circuit configured to generate a reference voltage level that is compensated for based on an internal temperature change, where the reference voltage level is adjusted based on a resistance value controlled in response to a control signal.

Abstract: A device includes a positive power supply voltage node; and a first operational amplifier including a first input, a second input, and an output coupled to the second input. The device further includes a first resistor coupled between the second input of the first operational amplifier and the positive power supply voltage node; a second resistor coupled between the output of the first operational amplifier and an electrical ground, and is configured to receive a same current flowing through the first resistor; a second operational amplifier including a first input coupled to the second resistor, and an output coupled to an output node; and a third resistor coupled between the electrical ground and a second input of the second operational amplifier.

Abstract: The present invention is contrived to adopt a differential pair type amplifier circuit comprising a differential pair constituted by a first transistor receiving an input of a first signal and by a second transistor receiving an input of a third signal generated by outputting a second signal of which the voltage level is a power supply voltage. Elements requiring a matching are two transistors constituting the differential pair for the amplifier circuit. Because of this, the elements requiring a matching can be placed close to each other regardless of a layout between the amplifier circuits.

Abstract: In accordance with an embodiment of the present invention, a bandgap voltage reference circuit includes a group of X current sources, a plurality of circuit branches, and a plurality of switches. Each of the X current sources (where X?3) produces a corresponding current that is substantially equal to the currents produced by the other current sources within the group. The plurality of circuit branches of the bandgap voltage reference circuit are collectively used to produce a bandgap voltage output (VGO). Each of the plurality of circuit branches receives at least one of the currents not received by the other circuit branches. The plurality of switches (e.g., controlled by a controller) selectively change over time which of the currents produced by the current sources are received by which of the plurality of circuit branches of the bandgap voltage reference circuit.

Abstract: A temperature compensated bandgap reference circuit includes a bandgap voltage generator having a temperature dependent signal output and a correction circuit coupled to the output of the bandgap voltage generator and generating a second order quadratic signal which is complementary to the signal output.

Abstract: A BGR circuit includes a first bipolar transistor and a second bipolar transistor that are connected between a power supply terminal and a ground terminal, each base of the first bipolar transistor and the second bipolar transistor being connected to an output terminal. A first resistor is connected between the ground terminal and the first bipolar transistor. A second resistor and a third resistor are connected in series between the first resistor and the second bipolar transistor. A temperature correction circuit is connected between the ground terminal and a node between the second resistor and the third resistor, and includes a first transistor having a base connected to an end of the first bipolar transistor of the first resistor. The temperature correction circuit further includes a fourth resistor connected in series to the first transistor.

Abstract: Provided is a voltage regulator having a structure in which an output terminal of a first differential amplifier circuit is connected to a second differential amplifier circuit to control an output transistor by the second differential amplifier circuit. When low current consumption is required, the first differential amplifier circuit is suspended. When high-speed response is required, the first differential amplifier circuit is activated. The low-current consumption operation and the high-speed operation are switched with a minimum circuit area.

Abstract: A reference current source circuit includes a reference voltage generating module, a voltage buffer, an equivalent resistance, a filter capacitor, a current mirror module and a reference current outputting terminal. The voltage buffer includes an operational amplifier and a first FET. The current mirror module includes a second FET and a third FET. The equivalent resistor includes an oscillator, a fourth FET, a fifth FET and a capacitor connected to the fourth FET and the fifth FET. The oscillator is for generating a clock signal whose frequency is related to a charging and discharging capacitor in the oscillator to control charging and discharging of the capacitor in the equivalent resistance. The reference current outputting terminal is for outputting a reference current only related to a capacitance ratio of the capacitor to the charging and discharging capacitor. A reference current source system is further disclosed.

Abstract: A bandgap voltage generating circuit for generating a bandgap voltage has an operational amplifier that has two inputs and an output. A current mirror circuit has at least two parallel current paths. Each of the current paths is controlled by the output from the operational amplifier. One of the current paths is coupled to one of the two inputs to the operational amplifier. A resistor divide circuit is connected to the other current path. The resistor divide circuit provides the bandgap voltage of the circuit.

Abstract: A system for generating a high PSRR bandgap and current reference that includes a bandgap reference circuit for generating a first input and generating a bandgap reference voltage output. A current reference circuit for receiving a second input and generating a reference current. An internal resistor coupled to the first input from bandgap reference circuit and second input of the current reference circuit, wherein the current generated proportional to first input and the second input are generated as a function of the internal resistor. The system also includes a detection/monitoring circuit for bandgap reference output.

Abstract: A curvature-compensated band-gap voltage reference circuit includes an operational amplifier and a high-frequency gain stage coupled to an output of the operational amplifier. The circuit also includes an electronic device and a matching circuit.

Abstract: The invention provides a bandgap reference voltage generator. In one embodiment, the bandgap reference voltage generator includes a first current generator, a second current generator, and an output voltage generator. The first current generator generates a first current with a positive temperature coefficient. The second current generator generates a second current with a negative temperature coefficient. The output voltage generator generates a third current with a level equal to that of the first current, generates a fourth current with a level equal to that of the second current, adds the third current to the fourth current to obtain a combined current with a zero temperature coefficient, and generates a reference voltage according to the combined current.

Abstract: A reference power supply circuit includes an adjustable resistance network and a bandgap reference power supply circuit, in which the adjustable resistance network includes a first resistor end and a second resistor end, the resistance between the first resistor end and the second resistor end varies with a process deviation; the bandgap reference power supply circuit connects the first resistor end with the second resistor end, for generating a positive proportional to absolute temperature current flowing through the first resistor end and the second resistor end and for outputting a reference voltage related to the positive proportional to absolute temperature current. The reference power supply circuit has the advantageous of high precision and good temperature drift characteristic.

Abstract: A high current drive bandgap based voltage regulator for providing a reference voltage at a an output voltage at a designed output voltage value. The high current drive bandgap based voltage regulator includes a high current drive output transistor, a feedback network, an output terminal and an operational amplifier. The feedback network is coupled between the output of the transistor and the input of the transistor. The operational amplifier is in the feedback network and has at least two operational amplifier input terminals and an operational amplifier output terminal. The operational amplifier output terminal is coupled to the transistor input terminal, and the operational input terminals are coupled to the transistor output terminal. The output terminal of the high current drive bandgap based voltage regulator is coupled to the output of the high current drive transistor.

Abstract: There are provided a reference signal generator and a PWM control circuit for LCD backlight. The reference signal generator and the PWM control circuit for LCD backlight may be configured to respectively include: a current control unit that controls generation of a variable current sequentially changing; a current generating unit that generates a variable current changing sequentially; and a reference signal generating unit that controls charging until a charged voltage charged by the variable current generated by the current generating unit reaches a first reference voltage level, starts discharging when the charged voltage reaches the first reference voltage level, controls discharging until the charged voltage reaches a second reference voltage level, and generates a triangular wave reference signal that has a frequency buffering interval in which a frequency sequentially changes when the initial driving completion signal or the protection signal is input.

Abstract: Low noise bandgap voltage references using a cascaded sum of bipolar transistor cross coupled loops. These loops are designed to provide the total PTAT voltage necessary for one and two bandgap voltage references. The PTAT voltage noise is the square root of the sum of the squares of the noise voltage of each transistor in the loops. The total noise of the reference can be much lower than approaches using two or 4 bipolar devices to get a PTAT voltage and then gaining this PTAT voltage to the required total PTAT voltage. The cross coupled loops also reject noise in the current that bias them. Alternate embodiments are disclosed.

Abstract: A reference voltage generation circuit for outputting a reference voltage from an input voltage includes a specific voltage output unit for outputting a specific voltage from the input voltage; a first circuit section for outputting the reference voltage with a positive temperature property from the specific voltage output from the specific voltage output unit; and a second circuit section for setting a level of the reference voltage output from the first circuit section. The specific voltage output unit is formed of a regulator circuit having a first terminal connected to a power source. The first circuit section is formed of a bi-polar transistor element connected to a second terminal of the regulator circuit. The second circuit section is formed of a resistor connected to the second terminal of the regulator circuit, a collector terminal of the bi-polar transistor element, and an emitter terminal of the bi-polar transistor element.

Abstract: A temperature corrected voltage bandgap circuit is provided. The circuit includes first and second diode connected transistors. A first switched current source is coupled to the one transistor to inject or remove a first current into or from the emitter of that transistor. The first current is selected to correct for curvature in the output voltage of the bandgap circuit at one of hotter or colder temperatures.

Abstract: A bias circuit generates a bias voltage. The bias circuit includes a first, a second, and a third detection circuit and a summing circuit. The first detection circuit generates a first characterization voltage that represents a variation of a power supply voltage from a nominal voltage. The first characterization voltage increases as the power supply voltage decreases and the first characterization voltage decreases as the power supply voltage increases. The second detection circuit generates a second characterization voltage that represents a threshold voltage of one or more p-type transistors. The third detection circuit generates a third characterization voltage that represents a threshold voltage of one or more n-type transistors. The summing circuit generates the bias voltage that is the power supply voltage reduced by a weighted sum of the first, second, and third characterization voltages.

Abstract: A circuit for providing a reference voltage includes a bandgap reference circuit, a first unity gain buffer coupled to the bandgap reference circuit, a first switch for coupling a second reference voltage node to a third reference voltage node, a first capacitor coupled to the third reference voltage node, a second switch for coupling the third reference voltage node to a fourth reference voltage node, and a second capacitor coupled to the fourth reference voltage node, wherein during operation a fourth reference voltage at the fourth reference voltage node decays when the second capacitor discharges. A control circuit provides control signals for intermittently operating the bandgap reference circuit and for controlling the switches to recharge the second capacitor after the fourth reference voltage decays a predetermined amount.

Abstract: Offset calibration technique to improve performance of band gap voltage reference. An example of a bandgap reference source includes an output resistor, a first and second transistors and a differential amplifier. A positive-input calibration phase switch is in communication with a positive amplifier input, a emitter of the first and second transistor and a negative-input calibration phase switch in communication with the negative amplifier input, the emitter of the first and second transistor. A positive-output calibration phase switch is in communication with the positive amplifier output, the first and second terminal of the output resistor and a negative-output calibration phase switch is in communication with the negative amplifier output, the first and second terminal of the output resistor. An adjustable resistance is in communication with the emitter of the first transistor, the emitter of the second transistor, and the second terminal of the output resistor.

Abstract: A semiconductor device includes high-side and low-side switching elements totem-pole-connected between high-voltage-side and low-voltage-side potentials; a high-side drive circuit, having high-voltage and low-voltage terminals which are connected to a floating power supply, which supplies either a voltage at the high-voltage terminal or a voltage at the low-voltage terminal for driving the high-side switching element; and a low-side drive circuit driving the low-side switching element and a reference voltage circuit generating a reference voltage between the voltages at high-voltage and low-voltage terminals of the high-side drive circuit. The reference voltage circuit supplies the reference voltage to a connection point between the high-side and low-side switching elements. The semiconductor device includes a charging switching element having a control terminal, a first terminal connected to the low-voltage terminal of the high-side drive circuit, and a grounded second terminal.

Abstract: According to one embodiment, a reference signal generating circuit includes a first nonlinear element that generates a first reference voltage, a second nonlinear element that generates a second reference voltage, a current controlling circuit that controls a current flowing to the first nonlinear element and a current flowing to the second nonlinear element based on an output voltage of the current controlling circuit itself, and N temperature characteristic adjusting elements (N is an integer of 2 or larger) that individually adjust the temperature characteristics of the output voltage of the current controlling circuit.

Abstract: Embodiments of the present invention may provide an integrated circuit that may comprise a first transistor to receive an input voltage signal at its gate and generate an output voltage signal at its drain. Further, the integrated circuit may comprise a second transistor to form an active load of the first transistor, the second transistor may have its drain and gate coupled to the drain of the first transistor. In addition, the integrated circuit may comprise a third transistor to form a current mirror with the second transistor, a fourth transistor to form an active load of the third transistor, and a fifth transistor to form a current mirror with the fourth transistor. The fifth transistor may be connected to the drain of the second transistor. The integrated circuit may form an amplifier and Gm stage of a reference buffer.

Abstract: A semiconductor circuit includes a control signal generation circuit configured to generate control signals in response to a voltage characteristic determination signal and a reference voltage generation circuit configured to output a main reference voltage, having one of a first characteristic of being proportional to temperature, a second characteristic of being constant irrespective of temperature, and a third characteristic of being inversely proportional to temperature, in response to the control signals.

Abstract: A circuit includes a first PMOS transistor and a second PMOS transistor, wherein a gate of the second PMOS transistor is coupled to a gate and a drain of the first PMOS transistor; a first NMOS transistor having a drain coupled to a drain of the first PMOS transistor; and a second NMOS transistor, wherein a drain of the second NMOS transistor is coupled to a gate of the first NMOS transistor, a gate of the second NMOS transistor, and a drain of the second PMOS transistor. A first switch is coupled between the drain of the first PMOS transistor and the drain of the second PMOS transistor. A second switch is coupled between a source of the first NMOS transistor and an electrical ground. A third switch is coupled between a source of the second NMOS transistor and the electrical ground.

Abstract: The method adjusts a reference voltage of an electronic circuit based on a band-gap voltage supplied by a first band-gap stage. The band-gap stage includes a current source connected to a first branch, which includes a first configurable resistor in series with a first diode, and to a second branch, which includes a second configurable resistor connected to a complementary resistor in series with a second diode. The current source is a PMOS transistor controlled by an output voltage of a first operational amplifier of a current control loop. The appropriate binary word for configuring the configurable resistors is determined based on four band-gap voltage values measured at two different temperatures and two resistive values of the resistors configured by the same first binary word and by the same second binary word which is different from the first binary word.

Abstract: A clock generation circuit is provided, having a bandgap reference circuit, a frequency controlled resistor, a comparison circuit and a voltage controlled oscillator. The bandgap reference circuit generates a first voltage. The frequency controlled resistor is coupled to a first node to provide a second voltage. The comparison circuit generates a first current according to a difference between the first voltage and the second voltage. The voltage controlled oscillator outputs first, second and third output clocks according to a third voltage on a second node, wherein the third voltage is generated according to the first current, and the second and third output clocks are fed back to the frequency controlled resistor such that the frequency controlled resistor converts the first current into the second voltage according to the second and third output clocks.

Abstract: A semiconductor device, circuit, and AC and DC load switch for maintaining a small input-output differential voltage and providing a defined response. The load switch can include a pass element coupled to an input terminal and an output terminal. The pass element can include a control terminal, with the control terminal controlling a response of the pass element. The load switch can include a first loop coupled to the control terminal configured to control a voltage drop between the input terminal and the output terminal while maintaining high impedance with the pass element. The load switch can include a second loop coupled to the control terminal configured to provide a defined filter response from the input terminal. The defined response can be a low pass response, high pass response, or a band pass response. The passband and/or stopband of the response can be programmed.

Abstract: Circuits for generating a PTAT voltage as a base-emitter voltage difference between a pair of bipolar transistors. The circuits may form unit cells in a cascading voltage reference circuit that increases the PTAT voltage with each subsequent stage. The bipolar transistors are controlled using a biasing arrangement that includes an MOS transistor connected to a current mirror that provides the base current for the bipolar transistors. A voltage reference is formed by combining a PTAT voltage and a CTAT voltage at the last stage. The voltage reference may be obtained from the voltage at an emitter of one of the bipolar transistors in the last stage.

Abstract: The invention provides a voltage regulator including a voltage divider and a power supply. The voltage divider circuit includes a first, second, third PMOS transistors, a first NMOS transistor, a pull down circuit, and a switching capacitor circuit. The pull down circuit includes a plurality of switches controlled by a pull down control signal. The switching capacitor circuit controlled by a first control pulse includes a capacitor and provides the capacitor connected to the dividing voltage for a short period while the power supply starts up to provide the input voltage. The power supply includes a comparator and a power voltage switch. The comparator compares the dividing voltage and a reference voltage and outputs a comparison result correspondingly. The power voltage switch is controlled by the comparison result to provide the input voltage from a power voltage.

Abstract: Aspects of the disclosure provide an integrated circuit. The integrated circuit includes a first operational circuit module receiving a first supply voltage from a first voltage regulator that is external to the integrated circuit, and a first adaptive voltage scaling module to adjust the first supply voltage based on performance characteristics of the first operational circuit module. In an embodiment of the disclosure, the first adaptive voltage scaling module includes a first performance monitoring module. The performance monitoring module is disposed on the integrated circuit, and is configured to generate at least a first indicator corresponding to at least one performance characteristic of the first operational circuit module. Further, the first adaptive scaling module includes a first voltage requirement determination and voltage feedback generator module that is disposed on the integrated circuit, and is coupled to the first performance monitoring module.

Abstract: A booster circuit including an output terminal; a reference voltage generating section that generates a boosting reference voltage; a charge pump section that boosts the reference voltage and outputs the boosted reference voltage from the output terminal; and an output-terminal voltage holding section that holds the output terminal at a voltage of a high level at a standby time. The charge pump section includes an input node, at least one boosting node, at least one reference node, at least one boosting capacitor, and a plurality of switching transistors that are provided between the input node and the at least one boosting node, between a boosting node at a last stage and the output terminal, between the input node and the reference node, and between a reference potential and a reference node, and are switched on or off by a switch signal.

Abstract: An integrated circuit device has a primary voltage regulator and an ultra-low power secondary voltage regulator. The ultra-low power secondary voltage regulator supplies voltage to certain circuits used for providing data retention and dynamic operation, e.g., a real time clock and calendar (RTCC) when the integrated circuit device is in a low power sleep mode. The primary voltage regulator provides power to these same certain circuits when the integrated circuit is in an operational mode.

Abstract: A current reference circuit includes a proportional-to-absolute temperature (PTAT) current generator, a band-gap reference circuit and a current replication circuit. The PTAT generator generates a PTAT current. The band-gap reference circuit generates a reference voltage based on the PTAT current and generates a second current by cancelling a first current from the PTAT current. The first current has a zero temperature coefficient and the second current has a positive temperature coefficient. The current replication circuit replicates the first current based on the PTAT current and the second current.

Abstract: A band-gap reference voltage generator for generating a stable band-gap reference voltage including a chopped band-gap circuit, a first sample and hold circuit coupled to the chopped band-gap circuit, a second sample and hold circuit coupled to the chopped band-gap circuit, and an output circuit coupled to the first and second sample and hold circuits for generating the stable band-gap reference voltage.

Abstract: Techniques to perform bandgap circuit trimming that maximize the operating range and minimize the trimming time at which the bandgap will be accurate. A bandgap circuit output voltage may be trimmed by heating the circuit, supplying increasing input power to the bandgap circuit, and adjusting operational parameters of the bandgap circuit to generate a constant bandgap circuit output voltage. When the bandgap circuit output voltage may remain constant, a constant input power may be applied to the bandgap circuit and its output voltage may be adjusted to a predetermined voltage level.

Abstract: An object of the present invention is to generate a reference voltage that is stable in relation to manufacturing process variations, by matching the operating regions of the MOSFETs contributing to generation of the reference voltage.

Abstract: A start circuit including a load unit, a first switch, a second switch and a reset control circuit is provided. The load unit receives a power voltage. The first switch is electrically connected between a first end of the load unit and a ground, and receives a node voltage from a reference circuit. The second switch has a first end electrically connected to the reference circuit, a second end electrically connected to the ground, and a control end electrically connected to the second end of the load unit. The second switch determines whether to provide a start voltage to the reference circuit according to a conducting state thereof. The reset control circuit provides a discharge path between a control end of the first switch and the ground, and conducts the discharge path according to the power voltage during a period when the power voltage is smaller than a threshold voltage.

Abstract: A stepwise voltage ramp generator includes a tank capacitor, a terminal of which is coupled to a reference potential to be charged with a voltage ramp. A transistor couples the tank capacitor to a supply line. A diode-connected transistor, biased with a bias current is coupled to the transistor to form a current mirror. A by-pass switch is electrically coupled in parallel to the diode-connected transistor, and is controlled by a PWM timing signal, the duty-cycle of which determines a mean slope of the generated voltage ramp.

Abstract: A variable voltage generation circuit includes an amplifier, a P-type metal-oxide-semiconductor transistor, at least one variable resistor, and a lower resistor. Each variable resistor includes M resistors and M switches. An ith switch of the M switches has a first terminal coupled to a first terminal of the variable resistor, and a second terminal. An ith resistor has a first terminal coupled to the second terminal of the ith switch, and a second terminal coupled to a first terminal of an (i+1)th resistor, where 2?M, 1?i?M, and i and M are natural numbers. Therefore, the variable voltage generation circuit outputs at least one variable voltage according to a reference voltage, the at least one variable resistor, and the lower resistor.

Abstract: A circuit for providing a reference voltage includes a bandgap reference circuit, a first unity gain buffer coupled to the bandgap reference circuit, a first switch for coupling a second reference voltage node to a third reference voltage node, a first capacitor coupled to the third reference voltage node, a second switch for coupling the third reference voltage node to a fourth reference voltage node, and a second capacitor coupled to the fourth reference voltage node, wherein during operation a fourth reference voltage at the fourth reference voltage node decays when the second capacitor discharges. A control circuit provides control signals for intermittently operating the bandgap reference circuit and for controlling the switches to recharge the second capacitor after the fourth reference voltage decays a predetermined amount.

Abstract: A temperature independent reference circuit includes first and second bipolar transistors with commonly coupled bases. First and second resistors are coupled in series between the emitter of the second bipolar transistor and ground. The first and second resistors have first and second resistance values, R1 and R2, and third and second temperature coefficients, TC3 and TC2, respectively. The resistance values being such that a temperature coefficient of a difference between the base-emitter voltages of the first and second bipolar transistors, TC1, is substantially equal to TC2×(R2/(R1+R2))+TC3×(R1/R1+R2)), resulting in a reference current flowing through each of the first and second bipolar transistors that is substantially constant over temperature. A third resistor coupled between a node and the collector of the second bipolar transistor has a value such that a reference voltage generated at the node is substantially constant over temperature.

Abstract: A soft start circuit is disclosed. The soft start circuit includes a reference voltage generator configured to generate a reference voltage, a switch connected between an output node of the reference voltage generator and an output node of the soft start circuit and configured to selectively provide an output signal in response to a switch control signal, a capacitor connected between the switch and a ground, and a current source configured to generate a current having a different level in each of a plurality of intervals to charge the capacitor.