IMAGAV-1

Team: E. Roca, S. Espejo, R. Domínguez-Castro and A. Rodríguez-Vázquez.

Date: 1999

This prototype is a programmable IMAGer with AVeraging (IMAGAV-I) chip which is intended for averaging of different groups or sets of pixels formed by nXn kernels, nXm kernels or independent pixels of the array. The imager includes a 64x64 array which uses passive pixels with electronic shutter that can be randomly accessed by selecting row and column (Fig 2).

The read-out structure includes a sole charge integration amplifier with programmable gain, which is designed to work at a read-out frequency of up to 5MHz (Fig 3). This read-out stage contributes to reduce the fixed-pattern noise observed in other imagers where the pixels are read-out using an amplifier per column.

The chip can performe both averaging and binning of the signal charges depending on the selected feedback capacitor of the charge integration amplifier. The read-out process of the group of pixels can be done simultaneously and, up to a certain number of pixels, at the same read-out rate. For larger groups, this frequency must be reduced.

The selection of pixels is done by a two 6 bits words (one for addressing the columns and one for addressing the rows) and each word with a 6 bits mask which permits multiple selection. Besides of this type of selection, it exists another type, called accumulation mode, which permits the serial selection of the different pixels (accumulation of pixels) which are afterwards read-out simultaneously.

No experimental results are presently available since the prototype is now being tested.

Images List:

• Figure 1: Die microphotograph

• Figure 2: Pixel schematic: a) symbolic representation, b) electrical representation.

• Figure 3: Symbolic representation of the read-out circuitry.