5280 results about "Reference current" patented technology

One or more sense amplifiers for sensing the conduction current of non-volatile memory is controlled by signals that are timed by a reference sense amplifier having similar characteristics and operating conditions. In one aspect, a sensing period is determined by when the reference sense amplifier sensing a reference current detects an expected state. In another aspect, an integration period for an amplified output is determined by when the reference sense amplifier outputs an expected state. When these determined timings are used to control the one or more sense amplifiers, environment and systemic variations are tracked.

The invention provides an organic light emitting diode active driving system with current feedback, thereby a driving current for organic light emitting diode is not affected by variation of characteristic parameters of thin film transistor under an active driving mode. The active driving system in accordance with the invention includes a transistor and a current comparator for driving an organic light emitting diode. The transistor has two current carrying electrodes respectively connected to a cathode of the organic light emitting diode and ground, and a gate controlled by a data signal. The current comparator has two input terminals respectively receive a reference current with predetermined value and a driving current flowing through the organic light emitting diode. The current comparator compares the reference current and the driving current, and then outputs a voltage to the gate of the transistor in response to the comparison result so as to make the value of the driving current equal to that of the reference current. Therefore, the active driving system for organic light emitting diode array or flat panel display in accordance with the invention can achieve a desirable light emission uniformity.

A pixel circuit able to stably and correctly supply a current having a desired value to a light emitting diode of each pixel without being influenced by variation of a threshold value of an active element inside the pixel or variation of mobility and able to display a high quality image as a result of this, wherein a TFT as a fourth switch is turned on together with a TFT as a second switch at the time of an auto-zero operation, a reference current line is connected to a drive transistor of the pixel through a first node, and the variation of the threshold value Vth is corrected, whereby variation of the on current due to the mobility at the time of a white display can be suppressed and the uniformity with respect to variation in the mobility can be greatly enhanced, and a display device and a driving method of the pixel circuit.

A display panel driving device and driving method for providing high quality images without irregular luminance even after long-time use. The value of the light-emission drive current flowing when causing each light-emission elements bearing each pixel to independently emit light in succession is measured, then the luminance is corrected for each input pixel data based on the above light-emission drive current values, associated with the pixels corresponding to the input pixel data. According to another aspect, the voltage value of the drive voltage is adjusted in such a manner that one value among each measured light-emission drive current value becomes equal to a predetermined reference current value. According to a further aspect, the current value is measured while an off-set current component corresponding to a leak current of the display panel is added to the current outputted from the drive voltage generator circuit and the resultant current is supplied to each of the pixel portions.

An integrated circuit regulates current flowing from a battery to a load without requiring an external current sense resistor. The IC includes a primary charge pump; a model charge pump; a current sense circuit, a first control circuit to force a voltage level at the output of the model charge pump to be equal to a voltage level at the output of the primary charge pump; and, a second control circuit to force a model current put out by the model charge pump to be equal to a reference current. Current passing through the primary charge pump is regulated at a level established by the capacitance value of an external flying capacitor irrespective of input voltage variation of the battery power source.

The data line voltage on the data line of the AMOLED sub-pixels is measured while the OLED is being driven by a reference current, in order to determine the age of the OLED in the sub-pixel. The pixel transistor serves as a current source for driving the OLED in the sub-pixel with the reference current. The data line voltage is substantially equal to the forward voltage VF(aged) of the aged OLED being driven at the reference current. The forward voltage VF (un-aged) of a reference (un-aged) OLED sub-pixel also measured at the reference current, and is subtracted from the measured OLED diode forward voltage VF (aged) to obtain their difference ΔVF=VF(aged)−VF(un-aged). ΔVF is an indicator of the age of the OLED in the sub-pixel, and is used as an index to a look-up-table that stores the corresponding aging offset data for generating the incremental pixel current needed to maintain constant luminance in the aged OLED pixel.

AC module, integrating a solar battery and an inverter, can easily be connected with other plural AC modules in parallel by way of cascade connections. However, when the number of AC modules connected is improvidently increased, the current flowing through the current path or connector of the AC module exceeds a rated current. In view of this, the current detector detects a current in the collective-power current path of the AC module, and when the detected current value exceeds a value set in the reference current setting circuit, the current detector stops the inverter.

There are many inventions described and illustrated herein. In a first aspect, the present invention is a technique and circuitry for reading data that is stored in memory cells. In one embodiment of this aspect, the present invention is a technique and circuitry for generating a reference current that is used, in conjunction with a sense amplifier, to read data that is stored in memory cells of a DRAM device. The technique and circuitry for generating a reference current may be implemented using an analog configuration, a digital configuration, and / or combinations of analog and digital configurations.

A four level passive element cell has memory states corresponding to decreasing resistance levels, which are preferably mapped respectively to data states 11, 01, 00, and 10. The LSB and MSB are preferably mapped as part of different pages. To discriminate between memory cell states, the selected bit line current is sensed for at least two different combinations of reference current level and read bias voltage. A mid-level reference is used to read the LSB. When reading the MSB, a first reference between the 10 and 00 data states, and a second reference between 01 and 11 data states may be used, and the mid-level reference need not be used. In certain embodiments, the bit line current may be simultaneously compared against the first and second references, without requiring a delay to stabilize the bit line current to a different value, and the MSB generated accordingly.

A driving circuit in an organic electroluminescent device includes a gate driver unit for sequentially outputting a control signal to select gate lines in a luminescent array unit and a current driver unit for supplying picture data to a data lines in the luminescent array unit corresponding to the gate lines selected by the gate driver unit and selectively driving organic electroluminescent devices of the selected line. The driving circuit includes a minimum gray level judgment unit for determining whether the picture data is of a predetermined minimum gray level; and a switching unit for receiving a control signal according to the determination made by the minimum gray level judgment unit and for selectively supplying a reference voltage or a reference current to the selectively driven organic electroluminescent devices.

To provide a drive method capable of maintaining gradation display performance regardless of screen display brightness. Reference numeral 491R denotes a regulator used to control reference current for red (R). By adjusting a reference current for R linearly, it is possible to linearly vary a current flowing through a transistor 472a which constitutes a current mirror with a transistor 471R. This changes a current flowing through a transistor 472b which has received a current-based delivery from the transistor 472a in a transistor group 521a. This in turn causes changes to a transistor 473a in a transistor group 521b which constitutes a current mirror with the transistor 472b, resulting in changes to a transistor 473b which has received a current-based delivery from the transistor 473a. Thus, since drive current of the unit transistor 484 changes, programming current can be changed linearly. Reference numeral 491G denotes a regulator used to control reference current for green (G) and reference numeral 491B denotes a regulator used to control reference current for blue (B). By adjusting 491R, 491G, and 491B, it is possible to adjust white balance easily and change screen brightness easily. Besides, gradation display performance is maintained at any screen brightness.

A reference current source for a magnetic memory device is preferably configured with magnetic tunnel junction cells and includes more than four reference magnetic memory cells to improve reliability of the magnetic memory device and to reduce sensitivity at a device level to individual cell failures. The reference current source includes a large number of magnetic memory cells coupled in an array, and a current source provides a reference current dependent on the array resistance. In another embodiment a large number of magnetic memory cells are coupled to current sources that are summed and scaled to produce a reference current source. A current comparator senses the unknown state of a magnetic memory cell. In a further embodiment, an array of magnetic memory cells is configured to provide a non-volatile, adjustable resistance. In a further embodiment, the array of magnetic memory cells is configured with a tap to provide a non-volatile, adjustable potentiometer.

Edge rates for output driver transistors are increased for slower conditions such as caused by supply-voltage, temperature, and process variations. The edge rates are increased by increasing charging and discharging currents to the gates of the driver transistors. Process-sensing transistors have gates tied to power or ground. Current through the process-sensing transistors changes with supply-voltage, temperature, and process variations. The currents through process-sensing transistors are used to generate process-compensated voltages that bias current sources and sinks to adjust process-dependent currents. Process-independent or fixed current sources and sinks use process-independent reference voltages ultimately generated from reference currents that are not sensitive to process variations. The process-dependent-currents are subtracted from the fixed currents to produce the charging and discharging currents.

There are many inventions disclosed herein. In one aspect, the present inventions are directed to methods and circuitry to control, adjust, determine and / or modify the absolute and / or relative positioning or location (i.e., absolute or relative amount) of reference current which is employed by sensing circuitry to sense the data state of a memory cell during a read operation of one or more memory cells. The control, adjustment, determination and / or modification of the reference current levels may be implemented using many different, distinct and / or diverse techniques and circuitry, including both analog and digital techniques and circuitry.

A gain compensator compensates for the gain variation of a varactor-tuned voltage tuned oscillator (VCO) in a phase lock loop (PLL). The VCO includes a parallel LC circuit having multiple fixed capacitors that can be switched-in or switched-out of the LC circuit according to a capacitor control signal to perform band-select tuning of the VCO. The gain compensator compensates for the variable VCO gain by generating a charge pump reference current that is based on the same capacitor control signal that controls the fixed capacitors in the LC circuit. The gain compensator generates the charge pump reference current by replicating a reference scale current using unit current sources. The number of times the reference scale current is replicated is based on the fixed capacitance that is switched-in to the LC circuit and therefore the frequency band of the PLL. The reference scale current is generated based on a PLL control that specifics certain PLL characteristics such as reference frequency, loop bandwidth, and loop damping. Therefore, the reference pump current can be efficiently optimized for changing PLL operating conditions, in addition to compensating for variable VCO gain.

Systems and methods are provided herein for improving the selectivity and productivity of sensors via digital signal processing techniques. According to one illustrative embodiment, in an electrochemical method for monitoring of a select analyte in a mixed sample with an interfering analyte, an improvement is provided that includes applying a large amplitude potential stimulus waveform to the sample to generate a nonlinear current signal; and resolving a signal contribution from the select analyte in the generated signal by a vector projection method with an analyte vector comprising a plurality of real and imaginary parts of one or more Fourier coefficients at one or more frequencies of a reference current signal for the select analyte.

A PWM controller has a line voltage input that allows using a start-up resistor for both start-up and power-limit compensations so that it can save the power consumption, ease the PCB layout, and shrink the power supply size. In the integrated circuit, a current switch used for both start-up and line voltage sensing is composed of a diode and a switch transistor. A current multiplier is used to improve the precise by canceling the impact of the integrated resistor's absolute value, which is composed of a transistor loop, a constant current and a reference current. Thus, by properly selecting the value of the start-up resistor, an identical output power limit for low line and high line voltage input can be achieved.

A method and apparatus provide a state observer control system 600 for a motor 106 that uses an extended Kalman filter 330 to predict initial rotor position and afterwards accurately predict rotor position and / or speed under variable types of loading conditions. A control system model 300 is generated that allows variable setting of an initial rotor position to generate estimated rotor position and speed as outputs. The control system model 300 includes an EKF (extended Kalman filter) estimator 330, speed controller 322, a current controller 324, and a variable load component 310. During operation, EKF estimator 330 estimates rotor speed 327 and position 333 based on reference voltages 402, 404 and currents 1325 generated by speed and current controllers 322, 324 and input from frame transformers 326, 328. Additionally, the reference currents and voltages 402, 404, 1325 are frame-transformed to be used as feedback signals 418, 346 in the system 600 and as drive signals to control power to be applied to a motor load 602.

A computer program product, apparatus, and system, are disclosed for user authentication based on authentication credentials and location information. A computer program product performs operations for such authentication. These operations of the computer program product include referencing past user location information in response to an authentication validation request and referencing current user location information. These operations also include determining a maximum allowable distance between an authentication attempt location associated with the authentication attempt location identifier and a past location associated with the past user interaction location identifier, and managing the authentication attempt, in response to determining that the physical authentication attempt location is outside the maximum allowable distance. The computer program product, apparatus, and system thereby reduce the possibility of identity theft by adding an element of location awareness to the authentication process.

A disk drive is disclosed comprising a voice coil motor (VCM) driven in a PWM mode using model reference current feedback. The PWM circuitry and VCM form a plant transfer function which varies with changes to the plant characteristics, such as the resistance of the voice coil fluctuating with temperature drift. A plant model having a model transfer function generates an estimated state of the VCM in response to a detected current flowing through the voice coil. A correction block, responsive to the detected current, adjusts PWM timing signals so that the plant transfer function substantially matches the model transfer function.

A multi-motor drive in which the resonance existing between one or more output filter capacitors of a current source inverter and an a.c. induction motor is reduced. The inverter features a switching pattern generator which controls the power switches of the inverter based on a reference current. A control loop, connected to the switching pattern generator, measures the load current or voltage and generates a nominal reference current based on an error therein; determines a damping current based on the voltage at the terminal; and determines the reference current supplied to the switching pattern generator by subtracting the damping current from the nominal reference current. The invention essentially simulates the use of a physical damping resistor connected in parallel with each output filter capacitor, but without the corresponding energy loss. This form of active damping control is also applied to a resonance mode existing between the input filter capacitors of a PWM-based rectifier and the system inductance of a power source.

Methods and an apparatuses for generating a word-line voltage are disclosed. A word-line voltage generator includes a first current source, an adjustable current source, adjustable current sink, and a voltage converter, all operably coupled to a current sum node. The first current source generates a first current having a temperature coefficient substantially equal to a temperature coefficient of at least one bit cell. The adjustable current source generates a second current that is substantially independent of a temperature change. The adjustable current sink sinks a third current that is substantially independent of a temperature change. The voltage converter is configured for generating a word-line signal having a word-line voltage proportional to a reference current, wherein the reference current comprises the first current, plus the second current, and minus the third current.

A driver circuit includes a buck converter associated with each LED chain for supplying a load current thereto. The buck converter receives an input voltage and is configured to provide a supply voltage to the associated LED chain such that the resulting load current of the LED chain matches at least approximately a predefined reference current value. The driver circuit further includes a switching converter that receives a driver supply voltage from a power supply and provides, as an output voltage, the input voltage for the buck converters. The switching converter is configured to provide an input voltage to the buck converters such that the maximum of the ratios between the input voltage and the supply voltages provided to the LED chains matches a predefined tolerance reference ratio.