Abstract:
AN ADAPTABLE ANALOG READ-OUT INTERFACE CIRCUIT FOR ION-SENSITIVE FIELD EFFECT TRANSISTOR (ISFET) HAS BEEN INVENTED THAT USES A CMOS TEMPERATURE SENSOR (THRESHOLD VOLTAGE EXTRACTION) TO IMPROVE THE THERMAL STABILITY OF THE ISFET. THE IMPROVEMENT IS ACHIEVED BY SUMMATION OF THE POSITIVE TEMPERATURE COEFFICIENT OF THE ISFET AND THE NEGATIVE COEFFICIENT OF THE CMOS TEMPERATURE SENSOR.
Abstract:
The present invention relates to an analog read out interface circuit for hydrogen ion sensors, an more particularly for ion-sensitive field transistor pH sensor. An analog read-out interface circuit for ion sensor, comprising a constant voltage constant current circuit; a tunable temperature sensor based on CMOS parasitic bipolar transistor; a summation circuit; characterised in that the analog read-out interface circuit is operable with an option to adjust temperature coefficient (Tc) of the tunable temperature sensor and output voltage level.
Abstract:
An adaptable analog read-out interface circuit for ion-sensitive field effect transistor (ISFET) that uses a tungsten temperature sensor to improve the thermal stability of the ISFET. The improvement is achieved by summation of the positive temperature coefficient of the ISFET and the negative coefficient of the resistor temperature dependence.
Abstract:
An adaptable analog read-out interface circuit for ion-sensitive field effect transistor (ISFET) has been invented that uses a CMOS temperature sensor (threshold voltage extraction) to improve the thermal stability of the ISFET. The improvement is achieved by summation of the positive temperature coefficient of the ISFET and the negative coefficient of the CMOS temperature sensor.