Pierre-François Ruedi

A 0.18

This paper presents a novel sensor front-end circuit that addresses the issues of 1/f noise and distortion in a unique way by using canceling techniques. The proposed front-end is a fully differential transimpedance amplifier (TIA) targeted for current mode electrochemical biosensing applications. In this paper, we discuss the architecture of this canceling based front-end and the optimization methods followed for achieving low noise, low distortion performance at minimum current consumption are presented. To validate the employed canceling based front-end, it has been realized in a 0.18 μm CMOS process and the characterization results are presented. The front-end has also been tested as part of a complete wireless sensing system and the cyclic voltammetry (CV) test results from electrochemical sensors are provided. Overall current consumption in the front-end is 50 μA while operating on a 1.8 V supply.

\mu {\rm m}

A 128 x 128 pixels, 120 dB vision sensor extracting at the pixel level the contrast magnitude and direction of local image features is used to implement a lane tracking system. The contrast representation (relative change of illumination) delivered by the sensor is independent of the illumination level. Together with the high dynamic range of the sensor, it ensures a very stable image feature representation even with high spatial and temporal inhomogeneities of the illumination. Dispatching off chip image feature is done according to the contrast magnitude, prioritizing features with high contrast magnitude. This allows to reduce drastically the amount of data transmitted out of the chip, hence the processing power required for subsequent processing stages. To compensate for the low fill factor (9%) of the sensor, micro-lenses have been deposited which increase the sensitivity by a factor of 5, corresponding to an equivalent of 2000 ASA. An algorithm exploiting the contrast representation output by the vision sensor has been developed to estimate the position of a vehicle relative to the road markings. The algorithm first detects the road markings based on the contrast direction map. Then, it performs quadratic fits on selected kernel of 3 by 3 pixels to achieve sub-pixel accuracy on the estimation of the lane marking positions. The resulting precision on the estimation of the vehicle lateral position is 1 cm. The algorithm performs efficiently under a wide variety of environmental conditions, including night and rainy conditions.

Biosensor Front-End Based on

This paper presents a front-end circuit for electrochemical biosensors used in applications like DNA sensing. Novelty in this work lies in the front-end architecture which uses noise canceling (NC) combined with chopper stabilization (CS) for rejecting 1/f noise and to our knowledge, a front-end using the principle of noise canceling for 1/f noise rejection has not been reported. Motivation for using this front-end are: 1) The circuit exhibits low noise performance with its sensitivity not being limited by 1/f noise thanks to noise canceling and chopping. 2) The canceling property in this topology is used effectively to achieve improved linearity and higher dynamic range (DR) in addition to 1/f noise rejection. The fully differential front-end circuit is designed in 0.18 μm CMOS process and consumes 46 μA while operating on 1.8 V supply voltage. Based on the simulation results, a DR improvement of greater than 10 dB is achieved by the use of canceling technique.

1/f

A low cost autonomous vision system for real-time applications in natural environments has been realized. It encompasses a 160 by 128 pixel 120 dB dynamic range vision sensor performing contrast magnitude and direction computation at the pixel level (Ruedi, 2003), a BF 533 BlackFin processor, memory and a low data rate RF link usable to communicate the high level information extracted from the scene to a network of such devices. Used to implement a road marking detection algorithm, it proved to perform reliably at 25 frames per second in highly changing conditions ranging from night to sun in the field of view