519 results about "Feedback capacitor" patented technology

A method of producing a diode drive current in an oximeter includes sensing at least a part of a current passing through the diode and converting the sensed current to a sensed voltage, inputting the sensed voltage to a feedback amplifier for stabilizing the current passing through the diode, and eliminating an offset voltage across inputs of the feedback amplifier. A pulse oximeter includes a diode for emitting light flashes, a feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier stabilizing a current passing through the diode, a nulling amplifier having inputs, a nulling capacitor, and an output, the nulling amplifier charging and discharging the feedback capacitor until the inputs of the feedback amplifier are at a same voltage. The operation may include synchronizing an elimination of input offset voltages of the feedback and nulling amplifiers with on or off state of diode current.

Line load compensation and reflection reduction in a signal transmitting circuit is provided using feedback capacitors. The feedback capacitor serially coupled with a resistance generates an RC rise/fall time that is independent of the line load. Additionally, by selecting a capacitor that yields a rise/fall time of approximately ⅓ of the maximum bit transmission time, signal reflection on the signal line can be reduced. Accordingly, by incorporating the feedback capacitor with a differential drive circuit, such as the IB 485 driver, variations in line load can be compensated for while also reducing signal reflection due to un-terminated or improperly terminated signal lines, thus allowing a free topology implementation.

A decoupled switched current temperature circuit with compounded DELTA Vbe includes an amplifier having an inverting input with corresponding non-inverting output and a non-inverting input with a corresponding inverting output; a PN junction connected to the non-inverting input through a first input capacitor and a voltage reference circuit is connected to the inverting input through a second input capacitor; a current supply includes a low current source and a high current source; a switching device applies the high current source to the PN junction and applies the low current source to the PN junction for providing the DELTA Vbe of the PN junction to the first capacitor; a first feedback capacitor is interconnected between the inverting output and the non-inverting input and a second feedback capacitor is interconnected between the non-inverting output and inverting input of the amplifier to define the gain on each of the inputs to produce a differential voltage across the outputs representative of the temperature of the PN junction; first and second reset switching devices discharge the first and second feedback capacitors, respectively, and a multi-phase switched device alternately interchanges the connection of the first and second input capacitors with the amplifier inputs for compounding the single DELTA Vbe .

A pixel capable for compensating for the degradation of an organic light emitting diode. The pixel includes an organic light emitting diode; a pixel circuit including a driving transistor for controlling an electric current capacity flowing from a first power source to a second power source via the organic light emitting diode; and a compensation unit for controlling a voltage of a gate electrode of the driving transistor to correspond to a degradation of the organic light emitting diode. The compensation unit includes first and second feedback capacitors coupled in series between an anode electrode of the organic light emitting diode and the gate electrode of the driving transistor and a switching transistor coupled between a common node of the first and second feedback capacitors and a reset power source and for turning on when a control signal is supplied to a control line coupled to the switching electrode.

The present invention relates to a capacitive fingerprint sensing device comprising a semiconductor substrate; and an array of sensing elements formed on the semiconductor substrate. Each of the sensing elements comprises a protective dielectric top layer; a sensing structure arranged underneath the top layer; and a charge amplifier connected to the sensing structure. The charge amplifier comprises a negative input connected to the sensing structure; a positive input; an output providing a sensing signal; a feedback capacitor; and a sense transistor having a gate constituting the negative input. The sense transistor is formed in an insulated well in the semiconductor substrate. The fingerprint sensing device further comprises excitation signal providing circuitry connected to the positive input of the charge amplifier and the well for changing electric potentials of the sensing structure and the well, to thereby reduce the influence of parasitic capacitances in the sensing element.

A low-dropout regulator comprises a high-gain error amplifier having a differential input stage and a single-ended output, a high-swing high-positive-gain second stage with input connecting to the output of the error amplifier and a single-ended output, a p-type MOS transistor with gate terminal connecting to the output of the second stage, source terminal connecting to the supply voltage, and drain terminal to the output of the low-dropout regulator. A first-order high-pass feedback network connects the output of the low-dropout regulator and the positive input of the error amplifier, and a damping-factor-control means comprising a negative gain stage with a feedback capacitor connects the input and output of this gain stage. A capacitor is connected between the output of the error amplifier and the output of the low-dropout regulator, while a voltage reference connects to the negative input of the error amplifier. The regulator does not require an off-chip capacitor for stability and has improved load transient response and power supply rejection ratio.

Circuit and method for providing over-current and overloading protection with a single additional pin. A converter controller circuit is provided that includes a voltage controlled oscillator and outputs upper and lower gating signals for driving the upper and lower driving transistors in a voltage converter, for example, in an inductor-inductor capacitor half-bridge circuit topology. A current sense input pin of the circuit receives a voltage corresponding to the current flowing in the half-bridge circuit. A feedback input pin has an external capacitor coupled to it and receives a voltage from an output voltage sensor at the output terminals. Over-current protection is provided by sensing the voltage at the current sense input pin with no external components needed. Overload protection is provided by utilizing the external feedback capacitor and the feedback input pin during overload conditions. Methods for providing over-current and overload protection are disclosed.

A pixel capable of compensating for the deterioration of an organic light emitting diode (OLED). The pixel includes an OLED coupled between first and second power sources, a pixel circuit including a driving transistor coupled between the first power source and the OLED and having a gate electrode coupled to a first node so that driving current corresponding to a voltage applied to the first node is supplied to the OLED, and a compensation circuit for controlling the voltage of the first node in accordance with deterioration of the OLED to compensate for the deterioration of the OLED. The compensation circuit includes first and second transistors coupled between the OLED and a third power source, first and second feedback capacitors coupled between the first node and a second node that is between the first transistor and the second transistor, and a third transistor coupled to the third power source.

An image sensor includes a pixel array having vertical signal lines, each interconnected to one of columns of the pixel array, and a column processor including a unit readout circuit provided for each of sets of a predetermined number of columns. The unit readout circuit includes input switches, each connected to a corresponding one of the vertical signal lines and being sequentially turned on and off, an input capacitor having one end commonly connected to the input switches, a reference switch for selectively providing a reference voltage to the input capacitor, an operational amplifier connected to the other end of the input capacitor, a reset switch for selectively providing a short-circuit between input and output ends of the operational amplifier, and a feedback circuit provided for each of the columns and including a feedback switch and a feedback capacitor connected in series between the two ends of the operational amplifier.

A first stage circuit for a high-speed, high-resolution pipeline analog-to-digital converter (ADC) implements operational amplifier (opamp) sharing and capacitor sharing to combine the sample-and-hold (SAH) and the MDAC (multiplying digital to analog converter) functions in the first residue stage of the pipeline ADC. In one embodiment, the first stage circuit includes a sampling capacitor, an amplifier, a feedback capacitor array and a comparator. The sampling capacitor and the feedback capacitor array are configured by switches to operate in a sampling/MDAC mode, a discharge mode and a hold mode. In this manner, the sample-and-hold operation and the MDAC operation are merged into the first stage circuit of the pipeline ADC to achieve low power and high speed of operation.

A sensor arrangement (10) comprises an amplifier (11) having a signal input (12) to receive an input signal (SIN) and a signal output (13) to provide an amplified sensor signal (SOUT) that is an inverted signal with respect to the input signal (SIN). Furthermore, the sensor arrangement (10) comprises a feedback path connecting the signal output (13) to the signal input (12), wherein the feedback path comprises a series connection of a capacitive sensor (14) and a feedback capacitor (15). A voltage source arrangement (19) of the sensor arrangement (10) is connected to a feedback node (18) between the capacitive sensor (14) and the feedback capacitor (15).

The application of a non-zero voltage offset to rotating capacitors 1111 and 1112 permit the use of a single positive voltage supply. However, the precharging of the rotating capacitors 1111 and 1112 is power inefficient. A power efficient and low-noise precharging operation is realized through the sharing of the charge on a feedback capacitor 1075 and 1080 that is significantly larger than the rotating capacitors 1111. Once a precharging operation is complete, the charge on the feedback capacitor 1075 and 1080 is refreshed from its residual charge level (rather than zero charge level) to a desired charge level.

A capacitance type physical quantity detector includes a sensor unit of which the capacitance varies depending upon a change in the physical quantity and a C-V converter unit which converts a change in the capacitance of said sensor unit into a voltage. The C-V converter unit includes an operational amplifier, a feedback capacitor, switching means connected in parallel with said feedback capacitor, a reference voltage-generating circuit for applying a reference voltage to the operational amplifier, and a drive voltage-generating circuit for applying a drive voltage to said sensor unit. At least any one of the feedback capacitance of said feedback capacitor, the reference voltage formed by said reference voltage-generating circuit or the drive voltage formed by said drive voltage-generating circuit varies depending upon the temperature to correct temperature characteristics of the sensor unit.

The invention discloses a low dropout regulator which comprises a voltage input end and a voltage output end which is connected with a first grade operational amplifier, a second grade common-source amplifier and a third grade output circuit, wherein, the output end of the first grade operational amplifier is connected with the input end of the second grade amplifier; the output end of the second amplifier is connected with the input end of the third grade output circuit; the output end of the third grade output circuit is connected with the output end of modulating voltage, wherein, the regulator also comprises a feedback network which is connected between the output end of the modulating voltage and the inverting input end of the first grade operational amplifier; the non-inverting input end of the first grade operational amplifier receives reference voltage. The invention is characterized in that the regulator also comprises a feedback capacitor which is connected between the output end of the second common-source amplifier and the grid of a load current mirror at one side of the non-inverting input end of the first grade operational amplifier. Compared with the traditional voltage regulator, the regulator improves the suppression capability of the power supply noise of the voltage regulator at higher frequency band.

From a pixel array where imaging pixels are arranged, pixel signals of respective columns on a selected row are read in parallel in a horizontal blanking period of a horizontal period. The pixel signals of the respective columns are output to horizontal signal lines in an effective period of the horizontal period via charge integrating amps provided respectively for the columns, i.e., provided respectively for vertical signal lines, and are thereby transferred horizontally. In the charge integrating amps, it is possible to enter a standby state while holding the pixel signals by a holding voltage. Furthermore, in the charge integrating amps, a reference potential for precharging feedback capacitors for amps at the time of a reading operation is automatically controlled based on a black level. Furthermore, pixel signals from the respective charge integrating amps are horizontally transferred in parallel using a plurality of horizontal signal lines.

A pixel at an ith pixel row (i is a natural number) includes an organic light emitting diode (OLED); a driving transistor for supplying a current to the OLED and a storage capacitor between a gate electrode of the driving transistor and an (i−1)th emission control line; and a compensating unit for controlling a voltage of the gate electrode of the driving transistor to compensate for deterioration of the OLED. The compensating unit includes: a first compensating unit transistor and a second compensating unit transistor between the OLED and a first power source; first and second feedback capacitors between a second node between the first and second compensating unit transistors and a first node between the gate electrode of the driving transistor and the storage capacitor; and a third compensating unit transistor coupled between a third node between the first and second feedback capacitors and a reference voltage source.

The invention provides an optical-receiver preamplifier for receiving analog or digital optical signals. The preamplifier comprises a high-gain amplifier A1, an input circuit, a negative-feedback impedor Zf, a low-gain amplifier A2 adjustable in gain and a feedback capacitor Cff, wherein the input circuit takes a photoelectric converter as a main component; the negative-feedback impedor Zf is connected with the reverse input end and the output end of the A1; the feedback capacitor Cff connects the output end of the A2 with the reverse input end of the A1; and the output end of the A1 can be directly connected with the input end of the A2 or can be connected with the input end of the A2 through a buffer. Output signals of the preamplifier are taken out from the output end of the A1 or the output end of the buffer, and can be directly subjected to subsequent signal processing or be further amplified and then subjected to subsequent signal processing.