Design and long-term operation of high-temperature, bulk-CMOS integrated circuits for instrumentation and control

Researchers at Case Western Reserve University (CWRU) and BluBerry, LLC have worked to extend the useful operating temperature range of low-cost, bulk CMOS instrumentation and actuation ICs to greater than 200°C. In this manuscript, we review the motivation, challenges, and circuit techniques employed to operate bulk CMOS circuits at extended temperatures. Initial research at CWRU yielded monolithic clock oscillators, instrumentation amplifiers, and sigma-delta analog-to-digital converters capable of stable, high-performance operation beyond 200°C. To demonstrate the industrial potential for this technology, a set of three integrated circuits (ICs) was developed to support distributed engine controls for aerospace applications. The ICs were fabricated in a conventional, 0.5-μm bulk CMOS process and, in combination with a high-temperature microcontroller, include all the circuits required to form a “smart node” capable of providing local, closed-loop control of an aircraft actuator. Operation of the circuits has been demonstrated from -55 to 200°C on representative flight hardware. Long-term testing has shown that the custom ICs can withstand continuous operation at elevated temperatures for more than 4,500 hours with negligible performance shift.