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US 4,305,288 AGranted
Temperature sensing circuit
AssigneeGeneral Electric Company
InventorHarry J. Morris, Jr.
Life of this patent
Estimating the term…
Abstract
An improved temperature sensing circuit is disclosed comprising a power supply which forward biases a diode sensing element to control the gain of an operational amplifier. A temperature change causes the resistance of the diode to change, which changes its current flow. Since the anode of the diode is connected to the operational amplifier, the result is that the operational amplifier has a very linear output voltage proportional to temperature.
Claims7
A temperature sensing circuit comprising:
- (a) a power supply producing a stable output voltage;
- (b) a temperature sensing element comprised of a diode, said diode having a first end and a second end, said first end being connected to said output voltage of said power supply to forward bias said diode in the linear region of its characteristic curve at one specific point near cutoff to establish a given characteristic resistance for a given temperature, which characteristic resistance varies inversely with changes in temperature;
- and
- (c) a current to voltage transducer having at least one input terminal and an output terminal, one of said input terminals being connected to said second end of said temperature sensing element, whereby a voltage appearing at said output terminal is proportional to the temperature which is to be determined by said circuit and sensed by said diode.
1 more element
A temperature difference sensing circuit comprising:
- (a) a power supply producing a stable output voltage;
- (b) a first temperature sensing element having a first end and a second end, said first end being connected to said output voltage of said power supply;
- (c) a second temperature sensing element having a first end and a second end, said first end being connected to said output voltage of said power supply;
- (d) a current to voltage transducer having a first input terminal, a second input terminal and an output terminal, said first input terminal being connected to said second end of said first temperature sensing element, said second input terminal being connected to said second end of said second temperature sensing element, and said output terminal having a voltage proportional to the difference in temperature between said first and said second sensing elements;
- and
- (e) a first resistor having a first end and a second end, said first end being connected to said second end of said second temperature sensing element and said second end being connected to a ground potential.
3 more elements
Dependencies are inferred from the claim text.