General Signal Corporation

Other

Leeds & Northrup Company

John D Fogel

Ronald D Baxter

James G Connery

Spencer V Silverthorne

Will McAdam

Methods, apparatus and chip fabrication techniques are described which provide electrostatic discharge (ESD) protection to ion-sensitive field effect transistor (ISFET) based devices used to selectively measure ions in a liquid. According to one aspect of the invention, an ESD protection circuit, made up of conventional protective elements, is integrated onto the same silicon chip on which the ISFET is formed, along with an interface that is in contact with the liquid being measured and which does not open up paths for D.C. leakage currents between the ISFET and the liquid. According to a preferred embodiment of the invention, a capacitor structure is used as the interface between the protection circuit and the liquid sample. Further aspects of the invention are directed to methods per se for providing ESD protection for ISFET sensors utilizing the interface means (e.g, capacitor structure) referred to hereinabove, and processes for fabricating the novel interface on a silicon wafer.

ESD Protection of ISFET sensors

ESD protection of ISFET sensors

Apparatus for compensating for the IR drop in a polarographic type electrochemical cell which utilizes an injected current for in situ calibration includes means operable for a brief period of the current injection to change the cell bias so as to maintain the total cell current for that period at the value existing prior to current injection as well as means for maintaining throughout the remainder of the injection period the cell bias which exists at the end of the brief period.

Method and means for compensating for IR voltage drop in electrochemical

A signal compensating network for use with a sensing element having different rates of response for increasing or decreasing sensed quantities includes a differentiating amplifier having different time constants for increasing and decreasing input signals. The output from the differentiating amplifier is combined with a signal representing the magnitude of the input signal to produce an output.

Compensator for slowly responding sensors

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Schwenksville, PA, United States of America

John D Fogel