Pyxalis

E2v Semiconductors

Grégoire Chenebaux

Thierry Ligozat

Laurent Saint Martin

Ramp analog-digital converters used in matrix image sensors to provide a digital value representative of a level of illumination of a pixel are provided. Two voltage samples are applied to a comparator, a counter is used to count pulses at a frequency F from a starting instant of the ramp until a toggling of the comparator. Two other voltage samples, one of which is added to a linear voltage ramp having an identical starting instant and slope to the first ramp, are applied to a second comparator, a half counting frequency F/2 is applied to the counter from the toggling of one of the comparators, and the content of the counter at the moment of toggling of the other comparator is stored. Two measurements of samples of the same signal or of two different signals are averaged without undergoing a digital conversion for each signal and a digital addition.

Ramp analog-digital converter able to provide an average of two signals directly

An active pixel image sensor comprising a matrix of pixels organized in rows and columns and a read circuit comprising a distinct read pathway for each column of pixels, comprises: a photodiode, a storage node, a transfer transistor, a storage node reset transistor, a row select transistor and a transistor mounted as voltage follower; each read pathway comprises a subtraction block connected to receive, first, voltage at the terminals of the storage node of a pixel of the corresponding column and, second, a reference voltage of value substantially equal to the reset voltage of the pixels of the matrix seen at the input of the read pathway; the sensor comprises a controller for driving the transistors of pixels and the read circuit to perform an image acquisition in global shutter mode with subtraction of the reset noise and non-destructive reading of the pixels. A method for acquiring images is provided.

Active pixel image sensor operating in global shutter mode, subtraction of the reset noise and non-destructive read

Integrated circuits of large size produced by photorepetition of several mutually identical partial patterns are provided, more precisely to the compensation of propagation delays of signals (notably of clock signals) from one partial circuit to the following whereas the signals concerned must reach the various partial circuits simultaneously for proper operation of the whole. The compensation circuit provided in each partial circuit comprises a main transmission line for a master clock signal and a compensation line with multiple outputs, as well as a multiplexer for selecting one of the outputs, the output selected being different in the various partial circuits. The multiplexer provides a local clock signal in each partial circuit and these clock signals are synchronous despite the propagation delays.

Photorepeated integrated circuit with compensation of the propagation delays of signals, notably of clock signals

The invention relates to image sensors using a chip with cut corners. The sensor comprises a chip with cut corners comprising a matrix () of horizontal lines and vertical columns of photosensitive members, the matrix having a generally rectangular shape of horizontal width W and having four bevels, the sensor comprising as many current or voltage read blocks as there are matrix columns, in order to read the image signals detected by the photosensitive members, characterized in that the current or voltage read blocks are placed in a row () along a horizontal edge of the matrix of width W' and are all housed within a vertical strip, the width Wof which is substantially less than the maximum width W of the matrix. There are two superposed rows of current read blocks with blocks distributed at the same pitch as the pixel columns, or there is a single row with read blocks distributed with a pitch less than that of the pixel columns. The invention can be applied to CMOS technology intraoral radiological sensors.

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Grenoble, France

Grégoire Chenebaux