Csem Centre Suisse D'electronique Et De Microtechnique Sa

Asulab S.a.

Csem Centre Suisse D'electronique Et De Microtechnique Sa-Recherche Et Dévelopment

Csem Centre Suisse D'electronique Et De Microtechnique Sa Recherche Et Developpement

Stefan Lauxtermann

Joachim Grupp

Martin Waeny

Steve Tanner

Georg Paul Israel

Martin Wäny

The present invention concerns a method for operating a CMOS image sensor including a matrix of pixels arranged in a plurality of lines and columns. Each of the pixels include a photosensor element that accumulates charge carriers in proportion to the illumination. A storage device is able to be coupled to the photosensor element at a determined instant in order to generate a sampled signal, which is representative of the charge carriers accumulated by the photosensor. The storage device is intended to assure storage for the purpose of reading the sampling signal. According to the present invention, when the sampled signal which is stored across the storage means is read, the photosensor element is held at a voltage such that any charge carrier generated by the latter is drained and thus does not disturb the sampled signal stored on the storage device. The problem of diffusion of charge carriers typically encountered with such sensors when they are operated in accordance with conventional techniques is thus answered. This method allows use of such a sensor for applications where the exposure time of an image is a determining factor because it is very short.

Method for operating a CMOS image sensor

An active cell for a photosensitive sensor that includes photosensitive diode in which the transistors of the cell are implemented using CMOS technology. The cell operates with an exposure phase in which the quantity of light impinging on the cell is detected followed by a scanning phase during which the luminance information caused by the impinging light is extracted from the cell. The cell is arranged in such a way to virtually completely isolate the charge accumulation node from the remainder of the cell after the exposure phase to eliminate stray accumulation of charge carriers.

Active cell with analog storage for a CMOS technology photosensitive sensor

An integrated active pixel photosensor includes a matrix array of pixels. Each pixel includes a photosensitive component, an amplifier component and a reset to initial state component. The matrix array further includes, for controlling the pixels, an addressing device, a power supply device, a reset to initial state device and a device for reading luminance information picked up by the pixels to extract the information from the matrix array. The addressing, power supply, reset and reading devices are implemented by the same plurality of matrix array column and row lines. The photosensor further includes logic control devices external to the matrix array and connected to the column and row lines to enable selective control in each pixel of the power supply, addressing, return to initial state and read functions.

Matrix photosensor in which each pixel includes only two transistors

The optoelectronic sensor comprises at least two pixels ( ), each pixel ( ) comprising a photodiode ( ), and means for electrically connecting at least two pixels, the connecting means comprising FETs ( ) for switching the connection on or off. The pixels ( ) are designed in such a way that if, e.g., four pixels ( ) are connected the photocharges generated in the connected pixels ( ) are combined in one of the connected pixels ( ), whereby the spatial resolution of the sensor is reduced. A skimming FET ( ) arranged between the photodiode ( ) and a charge detection circuit ( ) offers a floating source and floating drain in each pixel ( ). Thus the sensor can be manufactured in CMOS technology and is suited for photocharge binning. The invention makes it possible to vary the spatial resolution, the light sensitivity and/or the readout velocity by purely electronic means. This has the advantage of an increased light sensitivity, and, moreover, of being offset free. The power consumption of the sensor is reduced at a constant frame frequency if the spatial resolution is reduced.

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Berikon, Switzerland

Stefan Lauxtermann