Hervé Mathias

An improved analog computation cell for Paris II, a programmable vision chip

An improved analog programmable computation cell is addressed. Based on an original methodology, the analog processor features high computational performance along with a reduced power consumption and die area. Simulations validate the concept. Comparisons with state of the art digital processors are given.

Low power image processing: analog versus digital comparison

In this paper, a programmable analog retina is presented and compared with state of the art MPU for embedded imaging applications. The comparison is based on the energy requirement to implement the same image processing task. Results showed that analog processing requires lower power consumption than digital processing. In addition, the execution time is shorter since the size of the retina is reasonably large.

High-Resolution Micro-Pirani Pressure Sensor With Transient Response Processing and Time-Constant Evaluation

A micro-Pirani pressure sensor, which consists of a pressure-dependent thermoresistance gauge, is traditionally exploited using a steady-state resistance measurement. Any signal variation occurs over an offset voltage due to the imperfection of the device, which affects the sensors sensitivity. This paper presents, for the first time, an experimental investigation of a micro-Pirani gauge based on its dynamic behavior when heated by a current step. Such processing magnifies the pressure dependence of the gauges signal by eliminating the constant offset influences on the measurement. Furthermore, a first-order low-pass filter step response identification of the experimental transient signal strongly reduces the noise influence on the measurement. Furthermore, such identification enables a direct calculation of the time constant. This paper investigates the pressure measurement based on the time-constant evaluation, which provides a range of measurement and a maximal sensitivity significantly shifted toward the atmospheric pressure compared to that of a traditionally processed Pirani gauge. The heating step, the recording of the transient response signal, and its digital postprocessing can be easily achieved by a small-sized controller. The proposed system provides a substantial performance enhancement of the micro-Pirani pressure sensor.

Exploration of analog pre-processing architectures for coarse low power motion detection

In a context of high performance low power integrated vision system design, a methodology based on the exploration of many architectural and algorithmic issues, relying on analog pre-processing of low-resolution images, is considered. In this paper we present the algorithm exploration performed for analog coarse motion detection and the corresponding SystemC model developed for coupling with a digital processing unit simulator.

A 120μW 240×110@25fps vision chip with ROI detection SIMD processing unit

A smart ultra-low power CMOS image sensor comprising an analog programmable processor array is reported. Compact and efficient motion detection algorithms are implemented to process sub-sampled images made of so-called macropixels. Only Regions of Interest (ROI) consisting of macropixels containing moving objects are read out. This drastically reduces power consumption: the 110×240 pixel image sensor fabricated in a 0.35μm technology features a power consumption of 120μW at 25fps.

A low drift, low noise detection IC applied to MEMS gyros

Today, the performance and size of micro-gyrometers are mainly limited by their associated electronics. Indeed detection electronics noise and drift induce respectively reduced resolution and stability whereas low drift associated electronics has not been studied. In order to increase the gyrometers performance, the development of a specific detection integrated circuit is presented and special care is taken on the low drift and low noise design.