Impact of self-heating and thermal coupling on analog circuits inSOI CMOS

摘要

This paper examines the influence of the static and dynamicnelectrothermal behavior of silicon-on-insulator (SOI) CMOS transistorsnon a range of primitive analog circuit cells. In addition to the morenwell-known self-heating close-range thermal coupling effects are alsonexamined. Particular emphasis is given to the impact of these effects onndrain current mismatch due to localized temperature differences. Dynamicnelectrothermal behavior in the time and frequency domains is alsonconsidered, measurements and analyses are presented for a simplenamplifier stage, current mirrors, a current output D/A converter, andnring oscillators fabricated in a 0.7-Μm SOI CMOS process. It is shownnthat circuits which rely strongly on matching, such as the currentnmirrors or D/A converter, are significantly affected by self-heating andnthermal coupling. Anomalies due to self-heating are also clearly visiblenin the small-signal characteristics of the amplifier stage. Self-heatingneffects are less significant for fast switching circuits. The paperndemonstrates how circuit-level simulations can be used to predictnundesirable nonisothermal operating conditions during the design stage