Circuit for processing signals supplied by a zirconium-type oxygen sensor
AssigneeMarelli Autronica S.p.A.
InventorsCesario Cianci, Franco Salerno
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Abstract
The circuit includes a differential voltage/current converter (V/I) for connection to the sensor (S), a differential transresistance amplifier (TDA) whose inputs are connected to the outputs of the converter (V/I), and a double-ended/single-ended converter (D/S) connected to the outputs of the amplifier (TDA). The circuit is conveniently formed as an integrated circuit by CMOS P-well technology.
Claims7
A circuit for processing signals supplied by a zirconium-dioxide oxygen sensor or lambda probe, particularly for use as an interface circuit between such a sensor and an electronic control unit in an emission control system of an internal combustion engine, the circuit including a voltage/current converter with two input terminals for connection to terminals of the oxygen sensor and an amplifier circuit connected to the output of the converter, wherein
- the voltage/current converter is differential and has two output terminals which, in operation, output two equal and opposite currents whose intensity is proportional to the voltage between the inputs of the converter, and
- the amplifier circuit is a differential trans-resistance amplifier with a high gain, having two inputs connected to the two output terminals of the converter and two output terminals between which there is a differential voltage proportional to the intensity of the currents output by the converter in operation;
- wherein a double-ended/single-ended conversion circuit is connected to the two output terminals of the amplifier, and
- wherein the differential voltage-current converter has a differential input stage formed by N-channel CMOS P-well transistors each having its source connected to its P-well, the sources of the transistors acting as inputs for the converter.
Dependencies are inferred from the claim text.