Abstract

The CMOS image sensing device includes, on one integrated circuit, a sensor array and compensation circuitry for adjusting signals output from the sensor array to compensate for output signal variations, such as variations caused by voltage, temperature, process or manufacturing variations. The integrated circuit also includes logic circuitry for performing image processing operations on signals output from the sensor array including, for example, pattern recognition operations or filtering operations. In one embodiment, the integrated circuit includes a flash programmable memory array for storing compensation values corresponding to individual pixel elements of the sensor array. In use, the sensor array is illuminated by a flat light source, variations among the magnitude of analog output signals from the elements are detected and corresponding compensation values are calculated. The compensation values are flash programmed into the memory array. Thereafter, analog signals output from the sensor array are adjusted in accordance with the compensation values. In another arrangement, a separate flash programmable memory array is not provided. Rather, individual drive transistors of the pixel elements of the sensor array portion are directly flash programmed to achieve compensation. Passive and active photo detection pixel elements having flash programmable drive transistors are described.

Other References

• Microelectronics, Second Edition; Jacob Millman, Arvin Grabel; 1988; pp. 200-20