Precision temperature measurement using CMOS substrate pnp transistors

Author

Pertijs, Michiel A P ; Meijer, Gerard C M ; Huijsing, Johan H.

Author_Institution

Electron. Instrum. Lab., Delft Univ. of Technol., Netherlands

Volume

4

Issue

3

fYear

2004

fDate

6/1/2004 12:00:00 AM

Firstpage

294

Lastpage

300

Abstract

This paper analyzes the nonidealities of temperature sensors based on substrate pnp transistors and shows how their influence can be minimized. It focuses on temperature measurement using the difference between the base-emitter voltages of a transistor operated at two current densities. This difference is proportional to absolute temperature (PTAT). The effects of series resistance, current-gain variation, high-level injection, and the Early effect on the accuracy of this PTAT voltage are discussed. The results of measurements made on substrate pnp transistors in a standard 0.5-μm CMOS process are presented to illustrate the effects of these nonidealities. It is shown that the modeling of the PTAT voltage can be improved by taking the temperature dependency of the effective emission coefficient into account using the reverse Early effect. With this refinement, the temperature can be extracted from the measurement data with an absolute accuracy of ±0.1°C in the range of -50 to 130°C.

Keywords

CMOS integrated circuits; bipolar transistors; temperature measurement; temperature sensors; -50 to 130 C; 0.5 microns; CMOS process; Early effect; PTAT voltage; base-emitter voltages; current densities; current-gain variation; effective emission coefficient; high-level injection; proportional to absolute temperature; series resistance; substrate pnp transistors; temperature dependency; temperature measurement; temperature sensors; transistor; CMOS process; Current density; Electrical resistance measurement; Measurement standards; Semiconductor device modeling; Temperature dependence; Temperature distribution; Temperature measurement; Temperature sensors; Voltage; CMOS substrate pnp transistors; PTAT; effective emission coefficient; proportional to absolute temperature; reverse Early effect; temperature measurement; voltage;

fLanguage

English

Journal_Title

Sensors Journal, IEEE

Publisher

ieee

ISSN

1530-437X

Type

jour

DOI

10.1109/JSEN.2004.826742

Filename

1294908