A 128×128 CMOS image sensor with analog memory for synchronous image capture

Abstract

A 128 128 CMOS imager that permits synchronous capture is presented. The sensor combines the best of CMOS imagers (low-power, random readout, nondestructive readout, single supply voltage…) and synchronous capture [available in high-end charge coupled device (CCD) imagers]. The key point in obtaining such characteristics is the separation of the photosensor and the storage element. Although some sensors with these characteristics have been reported, in this sensor, the storage capability has been brought a step further, having storage times in the order of tens of seconds, and being able to use the array itself as a random access memory (RAM). This could avoid the use of external RAM, making the system simpler, more compact, and of low-power consumption.Index Terms-Active pixel sensor, analog memory, CMOS image sensors, machine vision.

A high speed programmable focal-plane SIMD vision chip

“…In order to increase the algorithmic possibilities of the architecture, one potential solution is the separation of the acquisition of the light inside the photodiode and the readout of the stored value at pixel-level [35]. One of the main advantages of such structures is that the capture sequence can be made in the first memory in parallel with a readout sequence and/or processing sequence of the previous image stored in the second memory, as shown in Fig.…”

A 10 000 fps CMOS Sensor With Massively Parallel Image Processing

“…In order to increase the algorithmic possibilities of the architecture, the key point is the separation of the acquisition of the light inside the photodiode and the readout of the stored value at pixel-level [36]. Thus, the storage element should keep the output voltage of the previous frames whereas the sensors integrate photocurrent for a new frame.…”

Autonomous mobile mini-robot with embedded CMOS vision system

“…The image is obtained by a proprietary CMOS image sensor [6]. The pixels have been designed with active pixel topology with a capacitor as the analog memory device ( fig.…”

“…After capture the image remains stored in the capacitors until the next acquisition procedure. The stored image in form of analog voltage can be randomly accessed by the external circuitry during several minutes as many times as necessary, without significant image degradation [6]. Table 2 summarises the vision system timing.…”

“…One possible solution is to integrate the analog to digital converters and associated frame grabber circuitry and another possible solution is to include the memory as pari of the pixel design. In the proposed vision system, a proprietary 128x128 pixels CMOS image sensor [6] with active pixel topology and circuitry for random pixel read-out is used. This sensor can be accessed without any additional external circuitry by a standard microcontroller [7].…”