Tt Electronics Plc

Alain Potteck

James Price Cusey

Tri-Tue Truong

A temperature-dependent current generator includes a first transistor connected between first and second nodes and providing a first voltage potential at the second node that decreases first order linearly when ambient temperature increases. The generator further includes an operational amplifier having first and second input terminals and an output terminal. The first input terminal is coupled to a second voltage potential that is first order independent of the ambient temperature. The second input terminal is coupled to a third node. The generator further includes a second transistor with gate, source, and drain terminals. The gate terminal is coupled to the output terminal of the operational amplifier. One of the source and drain terminals is coupled to the third node. The generator further includes a resistor coupled between the second and the third nodes. A resistance value of the resistor is first order independent of the ambient temperature.

Temperature compensation in optical sensing system

A temperature compensation circuit for a light source (e.g., light emitting diode (LED)) whose radiant energy output decreases when ambient temperature increases includes a first circuit element for generating a first current that increases proportional to an increase in the ambient temperature, and a second circuit element for generating a second current that is first order independent of the ambient temperature. The circuit further includes a weighted current adder for generating a third current by combining the first and second currents with first and second weights applied to the first and second currents respectively. The circuit further includes a third circuit element responsive to the third current for supplying a fourth current to the light source to maintain a radiant energy output of the light source constant independent of the ambient temperature.

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Montreal, Canada

Alain Potteck