A Temperature and Supply-Voltage Insensitive CMOS Current Reference

Seung-Hoon LEE  Yong JEE  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E82-C   No.8   pp.1562-1566
Publication Date: 1999/08/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
current reference,  CMOS,  low cost,  low voltage,  calibration,  

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Summary: 
In this work, a CMOS on-chip current reference circuit for memory, operational amplifiers, comparators, and data converters is proposed. The reference current is nearly insensitive to temperature and supply-voltage variations. In the proposed circuit, the current component with a positive temperature coefficient cancels that with a negative temperature coefficient each other. While conventional current reference circuits are based on bipolar transistors in BiCMOS, bipolar, or CMOS processes, the proposed circuit can be integrated on a single chip with other digital and analog circuits using a standard CMOS process and extra masks are not required. Measured results are demonstrated for two different prototypes. The first is fabricated employing a 1.0 µm p-well double-poly double-metal CMOS process and operates at 5 V nominally. The second, based on a 0.6 µm n-well process, is optimized for 3 V to 5 V operation. The latter prototype achieves the temperature coefficient of 98 ppm/ over a temperature range from -25 to 75 and the output variation of 1.5% with the supply-voltage changes from 2.5 V to 5.5 V. A simple calibration technique for reducing output current variations improves circuit yield.