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Polysilicon-Based Temperature Sensor

IP.com Disclosure Number: IPCOM000039579D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Cressler, JD: AUTHOR

Abstract

A technique is described whereby two different polysilicon-based resistors, that are compatible with standard bipolar manufacturing processes, provide characteristics to form a unique polysilicon-based temperature sensor. The resistors are two types of n0+ polysilicon resistors, fabricated in the same type of process as are transistors, to produce resistors having separate and distinct temperature vs. resistance characteristics. Fig. 1 shows the temperature vs. resistance curves for a diffused poly resistor labeled R1 and for a poly-on-oxide resistor labeled R2. R1 shows an increasing resistivity with temperature, while R2 shows a decreasing resistivity with increasing temperature. (Image Omitted) When the resistors are used in an electrical circuit, such as the differential circuit shown in Fig.

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Polysilicon-Based Temperature Sensor

A technique is described whereby two different polysilicon-based resistors, that are compatible with standard bipolar manufacturing processes, provide characteristics to form a unique polysilicon-based temperature sensor. The resistors are two types of n0+ polysilicon resistors, fabricated in the same type of process as are transistors, to produce resistors having separate and distinct temperature vs. resistance characteristics. Fig. 1 shows the temperature vs. resistance curves for a diffused poly resistor labeled R1 and for a poly-on-oxide resistor labeled R2. R1 shows an increasing resistivity with temperature, while R2 shows a decreasing resistivity with increasing temperature.

(Image Omitted)

When the resistors are used in an electrical circuit, such as the differential circuit shown in Fig. 2, a differential voltage is derived from the outputs V01 and V02 and when properly calibrated, forms a reliable temperature sensor with the temperature vs. voltage characteristic shown in Fig. 3. The output voltages may be buffered and amplified as required. It should be noted that although the characteristics of polysilicon are usually process sensitive, the resistance vs temperature behavior will always follow the general trend as indicated. Therefore, a simple recalibration will enable the sensor to be used in different bipolar processes. Although sheet resistances of the two resistors are usually different, the absolute value of...