A Charge Balancing 1450 um2 PNP-Based Thermal Sensor for Dense Thermal Monitoring

Thermal sensors are used in CPU's to detect hot spots and determine voltage levels. Since thermal gradients can be instruction dependent, there can be as many as 40 sensors/chip, which requires them to be compact. The industry standard for thermal sensors is the bandgap based PNP BJT sensor, be...

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Bibliographic Details
Published in:IEEE transactions on circuits and systems. II, Express briefs Express briefs, 2020-12, Vol.67 (12), p.2963-2967
Main Authors: Bass, Ori, Shor, Joseph
Format: Article
Language:English
Subjects:
Bandgap reference
Calibration
Capacitors
CMOS
Industry standards
Monitoring
Sensors
sigma-delta thermal sensor
Temperature measurement
Temperature sensors
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Summary:Thermal sensors are used in CPU's to detect hot spots and determine voltage levels. Since thermal gradients can be instruction dependent, there can be as many as 40 sensors/chip, which requires them to be compact. The industry standard for thermal sensors is the bandgap based PNP BJT sensor, because of its predictable and well-known physics. In this brief, a 1450 um2 charge-sharing BJT-based thermal sensor, with a 50 um2 sensing element, in 65nm is described. After a 1-point trim, the sensor exhibits a peak-to-peak accuracy of -2/+4°C over a 150°C range. After a 2-point trim, this becomes -2.5/+1.5°C over the same range. It also achieves a resolution of 0.22°C in an 821μs conversion time. These specifications, as well as the small area, make the sensor attractive for dense CPU thermal monitoring.
ISSN:1549-7747
1558-3791
DOI:10.1109/TCSII.2020.2999494