A. Simoni

A single-chip optical sensor with analog memory for motion detection

A 64/spl times/64-pixel image sensor with full-frame analog memory and on-chip motion processor is presented. The processor consists of a charge amplifier and an analog subtractor. It uses the switched-capacitor technique and calculates the difference between the values of the signal on each pixel in successive frames. The rate can achieve up to 60 frames/s with limited area and power overhead. The analog memory required for the storage of the previous frame is implemented using implanted capacitors placed within the sensor array. Fabricated in a 1.2-/spl mu/m standard CMOS process with an added metal 3 light-shielding layer, the circuit is fully functional and requires a total core area of 13 mm/sup 2/. >

Analog-to-digital conversion architectures for intelligent optical sensor arrays

This paper presents a comparative analysis of different analog-to-digital conversion architectures optimized for operation in close coupling with optical sensor arrays in the presence of stringent design constraints such as signal and noise levels, conversion rates and physical size of the array. Architectures based on a single converter per array and on multiple converters per array are considered. Measurement results on dedicated converters integrated in experimental chips together with optical arrays have proved the validity of the architectures presented, with different trade-off points in term of power consumption, conversion rate and spatial uniformity.

A photosensor array for spectrophotometry

A monolithic intelligent CMOS photosensor array specifically aimed at spectrophotometry is presented in which a linear photodiode array is integrated together with a charge amplifier, an analogue-to-digital converter, a digital programmable polynomial solver for pixel-level calibration, a set of control registers and a processor interface. This architecture reduces noise effects by using large pixels and by closely coupling the analogue-to-digital converter to the photosensors. This also simplifies the user interface as all analogue circuits are on chip. A digital polynomial solver performs pixel-by-pixel calibration to compensate for source, transmission medium and sensor nonlinearities. Low power consumption and 5 V operation render the sensor suitable for portable applications. The sensor was fabricated in a standard 1.2 μm analogue CMOS technology with added light shield.

A 2D photosensor array with integrated charge amplifier

Abstract A two-dimensional photosensor array with integrated CMOS charge amplifier intended for use as a library cell in the implementation of intelligent optical sensors is presented. A single charge amplifier is used to convert the photogenerated charge to a voltage in an array of size n 2 . This circumvents the problems of other approaches, in which n sense amplifiers are pitch-matched with the sensor array and must therefore be made physically very narrow, a severe constraint on their performance and often a cause of response non-uniformity. Adequate d.c. gain and gain—bandwidth product of the charge amplifier ensure sufficient speed and accuracy for the 8-bit resolution needed in vision systems. Test results on an array fabricated in a 1.2 μm triple-metal CMOS technology confirm the feasibility of the approach for a 128 × 128-pixel photodiode array and its applicability to higher-resolution arrays.

CMOS front-end for optical rotary encoders

This paper presents a front-end circuit for optical rotary encoders. The light pulses modulated by the encoder disc are transduced into current signals, which are pre-processed and converted into digital waveforms related to the angular position information. The proposed front-end circuit is compensated against temperature drifts. Digitally programmable calibration is provided to account for spreads in light pulse power. Measurement results on integrated prototypes are shown.

Analog-to-digital converters for optical sensor arrays

The use of CMOS technology allows the monolithic integration of photosensor arrays together with analog-to-digital (A/D) conversion circuits. The structure of the array can be exploited to increase the connectivity between the sensor and the converter, which are in close coupling. Both single-converter per array and multiple-converter per array approaches are therefore possible. This paper presents a comparative study of different A/D conversion architectures incorporated in intelligent optical systems. The presented schemes have been validated by experimental evaluations.