1288 results about "Sample and hold" patented technology

Local oscillator circuitry for an antenna array is disclosed. The circuitry includes an array of rotary traveling wave oscillators which are arranged in a pattern over an area and coupled so as to make them coherent. This provides for a set of phase synchronous local oscillators distributed over a large area. The array also includes a plurality of phase shifters each of which is connected to one of the rotary oscillators to provide a phase shifted local oscillator for the array. The phase shifter optionally includes a cycle counter that is configured to count cycles of the rotary oscillator to which it is connected and control circuitry that is then operative to provide a shifted rotary oscillator output based on the count from the cycle counter. A system and method for operating a true-time delay phased array antenna system. The system includes a plurality of antenna element circuits for driving or receiving an rf signal from the elements of the array. Each element circuit has a transmit and a receive path and a local multiphase oscillator, such as a rotary traveling wave oscillator. Each path has an analog delay line for providing a true-time delay for the antenna element. Preferably, the analog delay line is a charge coupled device whose control nodes are connected to phases of the local multiphase oscillator to implement a delay that is an integer number local multiphase oscillator periods. A fractional delay is also included in the path by using a sample and hold circuit connected to a particular phase of the oscillator. By delaying each antenna element by a true time delay, broadband operation of the array is possible.

An adaptive switch mode LED driver provides an intelligent approach to driving multiple strings of LEDs. The LED driver determines an optimal current level for each LED channel from a limited set of allowed currents. The LDO driver then determines a PWM duty cycle for driving the LEDs in each LED channel to provide precise brightness control over the LED channels. Beneficially, the LED driver minimizes the power dissipation in the LDO circuits driving each LED string, while also ensuring that the currents in each LED string are maintained within a limited range. A sample and hold LDO allows PWM control over extreme duty cycles with very fast dynamic response. Furthermore, fault protection circuitry ensures fault-free startup and operation of the LED driver.

An active pixel sensor (APS) image sensor comprises an array of pixel circuits corresponding to rows and columns of pixels, a plurality of amplifiers that buffer signals output by the array of pixel circuits, and a plurality of sample and hold circuits that read the buffered signals. A routing mechanism is positioned between the array of pixel circuits and the plurality of amplifiers. A controller selects a set of the pixel circuits for sampling and is configured to control the routing mechanism to couple each pixel circuit in the set to a different one of the amplifiers during a normal mode of operation and to couple each pixel circuit of a subset of pixel circuits in a first set of pixel circuits to a different amplifier of a first subset of the amplifiers, to couple each pixel circuit of a subset of pixel circuits in a second set of pixel circuits to a different amplifier of a second subset of the amplifiers, and to connect the amplifiers of the first and second subsets of amplifiers in pairs to a common one of the sample and hold circuits during a sub-sampling mode of operation.

A pulse-width-modulation control circuit of a switching-mode power converter with a primary-side feedback control is disclosed. The switching-mode power converter includes a transformer, a power switch, a current sensing resistor and the pulse-width-modulation control circuit. The transformer includes a primary-side winding, a secondary-side winding and an auxiliary winding. The pulse-width-modulation control circuit includes a sample and hold circuit, a transconductor circuit, an error amplifier and a pulse-width-modulation generator.

A method and apparatus for sensing and measuring stress waves. The method comprises the steps of: a.) sensing motion, where the motion comprises a stress wave component and a vibration component; b.) separating the stress wave component from the vibration component with a high pass filter to create a signal proportional to the stress wave; c.) amplifying the signal to create an amplified signal; d.) processing the amplified signal with a sample and hold peak detector over a predetermined interval of time to determine peaks of the amplified signal over said predetermined period of time; e.) creating an output signal proportional to the determined peaks of the amplified signal; and, f.) repeating steps d.) and e.). The invention also includes an apparatus for implementing the method of the invention.

A CMOS imager includes an array of active pixel sensors, wherein each pixel is associated with a respective column in the array. The imager also includes multiple circuits for reading out values of pixels from the active sensor array. Each readout circuit can be associated with a respective pair of columns in the array and can include first and second sample-and-hold circuits. The first and second sample-and-hold circuits are associated, respectively, with first and second columns of pixels in the array. Each readout circuit also includes an operational amplifier-based charge sensing circuit that selectively provides an amplified differential output signal based on signals sampled either by the first sample-and-hold circuit or the second sample-and-hold circuit. The readout circuit also has an analog-to-digital converter for converting the differential output to a corresponding digital signal using a successive approximation technique. Use of the readout circuit can increase the parallel structure of the overall chip, thereby reducing the bandwidth which each readout circuit must be capable of handling.

An over-power compensation circuit for use in a switched mode power supply having a current sense circuit for sensing a current flowing through a power transistor of the switched mode power supply. The over-power compensation circuit includes a peak detector, a sample-and-hold circuit, a current offset generator, and an offset resistor. The peak detector has an input for receiving an input voltage derived from the input line, and an output. The sample-and-hold circuit has an input connected to the output of the peak detector, and an output. The current offset generator has an input connected to the output of the sample-and-hold circuit, and an output for providing an offset current. The offset resistor has a first terminal connected to the output of the current offset generator, and a second terminal adapted to be connected to a current conducting electrode of the power transistor.

A primary side controlled power converter having a voltage sensing means coupled to a transformer of the power converter and configured to provide a voltage feedback waveform representative of an output of the transformer is provided. A primary switching circuit operates to control energy storage of a primary side of the transformer. The primary switching circuit is operable during an on time and inoperable during an off time. The on and off time is switched at a system frequency. A feedback amplifier generates an error signal indicative of a difference between the voltage feedback waveform and a reference voltage. A sample and hold circuit samples the error signal at a periodic frequency during the off time. An error signal amplifier is configured to provide the sampled value to the primary switching circuit wherein the primary switching circuit controls the transformer and thereby regulates an output of the power converter.

Vector signaling code communications systems rely on group transmission of code symbols using multiple signaling channels that may have differing propagation characteristics, resulting in differing received signal levels, waveforms, and symbol arrival times, and thus that should be actively monitored and adjusted to minimize differential signal characteristics. Information obtained during symbol decode may be analyzed to identify channel operational characteristics during normal operation and perform non-disruptive channel adjustments, including per-channel adjustment of sample-and-hold timing to realign code symbol groups. Initialization or start-up adjustment may also be performed using intentionally-transmitted training patterns.

The problem of charge leakage in the AC compensation filter for the error amplifier of a pulse width modulation (PWM)-based DC—DC converter is effectively obviated by controllably sampling and storing the voltage across the AC compensation filter, in response to a transition of the operation of a DC power supply from run or active mode to quiescent or sleep mode. The sampled voltage is retained as a compensation voltage throughout the quiescent mode, so that it will be immediately available to the PWM circuitry at the termination of the quiescent interval. This serves to ensure a relatively smooth (low noise) power supply switch-over during a subsequent transition from quiescent to active mode.

The present invention is directed to devices and methods for carrying out and/or monitoring biological reactions in response to electrical stimuli. A programmable multiplexed active biologic array includes an array of electrodes coupled to sample-and-hold circuits. The programmable multiplexed active biologic array includes a digital interface that allows external control of the array using an external processor. The circuit may monitor, digitally control, and deliver electrical stimuli to the electrodes individually or in selected groups.

An excitation coil (19) surrounding the periphery of the position detecting area is connected to an oscillating circuit (21), which oscillates at a frequency f₀, through a drive circuit (20). A CPU (18) supplies control signals to a selecting circuit (12), a sample-and-hold circuit (16), an A/D conversion circuit (17), and the drive circuit (20). Based on the control signal output from the CPU (18), the drive circuit (20) controls the power of the signal output from the excitation coil (19) to ON or OFF. Further, the strength of the excitation signal supplied from the excitation coil (19) is controlled based on information obtained by analyzing a signal received from a position indicator (40), such as the position indicated by the position indicator on the position detecting area and/or a strength of the signal received from the position indicator.

The present invention provides a multi-input A/D converter circuit capable of shorting a conversion time without increasing its layout area and current consumption. When a most significant bit of a binary counter is “L”, individual input signals are sampled by a sample and hold unit, and digital signals held in respective data holders are sequentially selected by a selector. When the most significant bit is brought to “H”, the respective input signals are held as analog signals and compared with each of reference voltages produced corresponding to a digital signal by a DAC. When decision signals outputted from comparators are changed from “L” to “H”, the digital signal at that time is held in the individual data holders as digital signals.

A pipelined analog-to-digital converter (ADC) (30) with improved precision is disclosed. The pipelined ADC (30) includes a sequence of stages (20), each of which includes a sample-and-hold circuit (22), an analog-to-digital converter (23), and the functions of a digital-to-analog converter (DAC) (25), an adder (24), and a gain stage (27) at which a residue signal (RES) is generated for application to the next stage (20) in the sequence. A multiplying DAC (28) performs the functions of the DAC (25), adder (24), and gain stage (27) in the stage (20), and is based on an operational amplifier (29). Sample capacitors (C10, C20) and reference capacitors (C12₂, C22₂) receive the analog input from the sample-and-hold circuit (22) in a sample phase; parallel capacitors (C12₁, C22₁) are provided to maintain constant circuit gain. Extended reference voltages (V_REFPX, V_REFNX) at levels that exceed the output range (V₀+, V₀−) of the operational amplifier (29) are applied to the reference capacitors, in response to the digital output of the analog-to-digital converter (23) in its stage (20). The reference capacitors (C12, C22) are scaled according to the extent to which the extended reference voltages (V_REFPX, V_REFNX) exceed the op amp output levels (V₀+, V₀−). The effects of noise on the reference voltages (V_REFPX, V_REFNX) on the residue signal (RES) are thus greatly reduced.

A switched mode power supply (SMPS) includes a transformer with a primary winding, a secondary winding, an auxiliary winding, and a power switch coupled to the primary winding. During one switching cycle, the auxiliary winding provides a feedback signal which includes a first voltage pulse that is induced after the power switch is turned on and a second voltage pulse that is induced after the power switch is turned off. A control circuit includes a circuit for generating a sampling signal for sampling the second voltage pulse in a switching cycle at a time that is determined based on the first voltage pulse in the same switching cycle. A sample-and-hold circuit is configured for sampling and storing the second voltage pulse in response to the sampling signal. A switching signal generating circuit is configured to generate a switching signal for controlling the power switch based on an output of the sample-and-hold circuit.

An information recording apparatus is provided, which can control over the power of light beams emitted from a light source and various types of servo control with higher accuracy. A laser beam is emitted from a semiconductor laser to write information onto an optical disc. A detection signal indicative of the power of the laser beam output from a light-receiving device is sampled and held with a sample and hold circuit via an I-V converter at a timing delayed by the time corresponding to the delay time of the I-V converter. A tracking error generation circuit and a focus error generation circuit generate a tracking error signal and a focus error signal, respectively, on the basis of a detection signal having information about tracking error and focus error and output from a light-receiving device. Sample and hold circuits sample and hold the tracking error signal and the focus error signal at a timing delayed by the time corresponding to the delay time of each of the generation circuits, respectively. Power control, tracking servo, and focus servo are performed using each of the signals held by the sample and hold circuits, respectively.