Intersil Americas Inc.

Polaroid Corporation

Imaging Devices, Inc.

James R Toker

Travis Guthrie

Brannon Craig Harris

Narendra Kayathi

Jerome Johnson Tiemann

Gerald J Michon

Munib A Wober

Chris Morrow Young

Sunder S Kidambi

Thomas L Vogelsong

William D Washkurak

R Daniel McGrath

Vincent S Clark

Lisa G Dron

Adolphus Kearney

Selim S Bencuya

A current measurement circuit may include unbuffered inputs, and the current may be sampled directly from the input pins. The input current created from each sample may be cancelled by injecting opposite charge on the subsequent sample. This direct sampling from the pins increases the common mode input range of the sense path without having to build high linearity rail-to-rail input buffers, hence lowering cost and power consumption of the current measurement path. It also allows for high-impedance input sampling. The measurement circuit may include multiple sampling stages, with a first sampling stage implemented as a switched-capacitor based circuit. A compensator circuit coupled in a feedback loop from the output of the first sampling stage to the input pins may be operated to provide the equivalent charge back to the input pins every cycle to cancel the input current required to charge the sampling capacitors of the first sampling stage.

Input current compensation during current measurement

An adjustable current-synthesizer may generate synthesized current representative of an actual current, according to a model of a circuit that produces the actual current. The current synthesizer may under-sample a current sense signal derived from the actual current to obtain a few samples of the actual current, which are then used to adjust the synthesized current, thereby ensuring accuracy of the synthesized current. Sample values of the actual current are compared with corresponding generated values of the synthesized current to obtain offset values. In order to maintain monotonicity in the synthesizer results, the offset values are used to make adjustments to the slope of the synthesized current. The slope of the synthesized current may also be adjusted according to the slope of the actual current. Sub-Nyquist sampling of the actual current may be performed on the down-slope, with up-slope adjustments made based on the offset adjustment and down-slope adjustment.

Current synthesizer correction

Voltage regulators in a current share arrangement may provide a total current to a common load, and may be simultaneously turned on to ramp up member currents. Each voltage regulator may provide a respective member current in the current share configuration. A target current value may be determined from a cycle-averaged current value of the member currents and a voltage error value of the voltage regulator, and each member current may be ramped to the target current value instead of the cycle-averaged current value when the voltage regulators are turned on, resulting in more stable and balanced current ramping. A predictive multi-phase digital controller may therefore operate according to a target current determined based on a measured or inferred inductor current and an error voltage. Pulse-width, pulse position and pulse frequency (adding or skipping pulses) may be calculated according to the operation of the predictive multi-phase digital controller.

Current ramping during multiphase current regulation

An imaging processor microcircuit incorporating an integral image buffer, preferably a synchronous random-access memory device. Access to the image buffer is controlled by an image buffer access prioritizer. When the prioritizer detects that a device desires image buffer access, it signals all lower-priority devices to suspend accesses until the higher-priority device has completed access. An image sensor interface transfers image sensor data to the image buffer. As each pixel data is read, it is modified by reference data read from the image buffer then stored in the image buffer. The read, modify, write process takes three of a possible five cycles, leaving two unused cycles for image buffer access by other devices. The image buffer is also temporary image storage for an optional LCD and an optional print engine. The LCD interface uses the unused cycles to read LCD image data.

Image processor with integral image buffer

An image sensing device comprising active pixels is disclosed, each pixel having a charge accumulation region for collecting charges generated by a photosensitive element such as a photodiode. Fixed pattern noise is minimized by utilizing a reference current to reset the pixels and to generate an output current signal.

Current-mediated active-pixel image sensing device with current reset

A charge injection imaging device comprises low bandwidth, low noise performance column amplifiers serially connected to respective charge coupled device storage lines. Image and/or noise defining electronic information signals are retrieved from the charge injection imaging device by way of the amplifiers and storage lines in a manner which provides image defining electronic information signals from which the noise defining electronic information signal portions have been automatically subtracted for each succeeding photosensitive element of the device. The subtracted noise portions include both KTC noise and fixed pattern noise which are normally inherently associated with the image defining electronic information signals retrieved from the charge injection imaging device.

Charge injection device with low noise readout

Growing community of inventors

Cambridge, MA, United States of America

James R Toker