<p>This thesis investigates the possibility of realizing bandgap reference crcuits for processes having sub-1V supply voltage. With the scaling of gate oxide thickness supply voltage is getting reduced. But the threshold voltage of transistors is not getting scaled at the same rate as that of the supply voltage. This makes it difficult to incorporate conventional designs of bandgap reference circuits to processeshaving near to 1V supply voltage. In the first part of the thesis a comprehensive study on existing low voltage bandgap reference circuits is done. Using these ideas a low-power, low-voltage bandgap reference circuit is designed in the second part of the thesis work. </p><p>The proposed bandgap reference circuit is capable of generating a reference voltage of 0.730V. The circuit is implemented in 0.18µm standard CMOS technology and operates with 0.9V supply voltage, consuming 5µA current. The circuit achieves 7 ppm/K of temperature coefficient with supply voltage range from 0.9 to 1.5V and temperature range from 0 to 60C.</p>

This thesis investigates the possibility of realizing bandgap reference crcuits for processes having sub-1V supply voltage. With the scaling of gate oxide thickness supply voltage is getting reduced. But the threshold voltage of transistors is not getting scaled at the same rate as that of the supply voltage. This makes it difficult to incorporate conventional designs of bandgap reference circuits to processeshaving near to 1V supply voltage. In the first part of the thesis a comprehensive study on existing low voltage bandgap reference circuits is done. Using these ideas a low-power, low-voltage bandgap reference circuit is designed in the second part of the thesis work. The proposed bandgap reference circuit is capable of generating a reference voltage of 0.730V. The circuit is implemented in 0.18µm standard CMOS technology and operates with 0.9V supply voltage, consuming 5µA current. The circuit achieves 7 ppm/K of temperature coefficient with supply voltage range from 0.9 to 1.5V and temperature range from 0 to 60C.

Les capteurs d’images CMOS sont de plus en plus utilisés dans le domaine industriel : la surveillance, la défense, le médical, etc. Dans ces domaines, les capteurs d?images CMOS sont exposés potentiellement à de grandes variations de température. Les capteurs d?images CMOS, comme tous les circuits analogiques, sont très sensibles aux variations de température, ce qui limite leurs applications. Jusquà présent, aucune solution intégrée pour contrer ce problème n’a été proposée. Afin de remédier à ce défaut, nous étudions, dans cette thèse, les effets de la température sur les deux types d?imageurs les plus connus. Plusieurs structures de compensation sont proposées. Elles reprennent globalement les trois méthodes existantes et jamais appliquées aux capteurs d’images. La première méthode utilise une entrée au niveau du pixel qui sera modulée en fonction de l’évolution de la température. La deuxième méthode utilise la technique ZTC (Zero Temperature Coefficient). La troisième méthode est inspirée de la méthode de la tension de référence bandgap. Dans tous les cas, nous réduisons de manière très intéressante l’effet de la température et nous obtenons une bonne stabilité en température de -30 à 125°C. Toutes les solutions proposées préservent le fonctionnement initial de l’imageur. Elles n’impactent également pas ou peu la surface du pixel / CMOS image sensors find widespread use in various industrial applications including military, surveillance, medical, etc. In these applications, CMOS image sensors are often exposed to large temperature variations. As analog circuits, these CMOS image sensors are very sensitive to temperature variations, which limit their applications. Until now, no integrated solution for this problem has been proposed. To solve this problem, we study, in this thesis, the temperature effects on the two most known types of CMOS image sensors. Several compensation structures are proposed. They generally return to the three existing methods and never applied to image sensors. The first method uses an entrance at the pixel level to be adjusted according to changes in temperature. The second method uses the ZTC (Zero Temperature Coefficient) technique. The third method is based on the method of the bandgap voltage reference. In all cases, we reduce a very interesting way the temperature effect and we get a good temperature stability of the sensor from -30 to 125°C. All the solutions preserve the initial operation of the imager. They also affect a little or not the surface of the pixel.