SBCCI 2013 - PTAT CMOS Current Sources Mismatch over Temperature

PTAT CMOS Current Sources Mismatch over Temperature

Andre Luiz Aita and Cesar Ramos Rodrigues

The 26th Symposium on Integrated Circuits and System Design (SBCCI 2013)
Curitiba - Brazil, September 2nd to 6th, 2013

Abstract

Proportional to Absolute Temperature (PTAT) CMOS current sources are widely used in temperature sensors, bandgap references, and other temperature-compensating circuits. Most of these applications strongly rely on the accuracy of a current ratio m established with a set of 1+m PTAT current sources. However, a PTAT CMOS current source has a temperature-dependent bias point, which in turn, has a well-known effect on the mismatch of CMOS current sources. This paper analyzes the mismatching properties of PTAT current sources due to variation of the current-sources bias point (gm/IDS) with temperature, from -55oC to 125oC. After the analysis, the paper shows measurements of a precision temperature sensor without mismatch compensation to corroborate the analysis developed.

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