A time-domain CMOS oscillator-based thermostat with digital set-point programming.

Area of Science:

• Integrated Circuit Design
• Embedded Systems
• Thermal Management

Background:

• Modern VLSI systems require effective on-chip thermal management to ensure reliability and performance.
• Existing thermal management solutions often involve bulky components like Digital-to-Analog Converters (DACs) or external resistors, increasing chip size and power consumption.
• Scaling down fabrication processes necessitates integrated solutions that are both power-efficient and compact.

Purpose of the Study:

• To present a time-domain CMOS oscillator-based thermostat for on-chip thermal management.
• To achieve digital set-point programming without a DAC or external resistor.
• To enhance cost-effectiveness and accuracy in thermal management solutions.

Main Methods:

• Utilized a time-domain delay-line-based thermostat architecture with multiplexers (MUXs) for reduced power and size.
• Proposed a novel thermostat design employing two oscillators for time-domain curvature compensation, replacing longer linear delay lines.
• Implemented a time comparator with custom hysteresis for temperature alarm and control signal generation.

Main Results:

• Achieved a compact chip size of 0.12 mm² in a 0.35-mm TSMC CMOS process.
• Demonstrated operation across a temperature range of 0 to 90 °C.
• Attained a high resolution (< 0.05 °C) and improved inaccuracy (± 0.6 °C after calibration).
• Recorded a low power consumption of 30 µW at a 10 samples/s rate.

Conclusions:

• The proposed oscillator-based thermostat offers a power-efficient and compact solution for on-chip thermal management in VLSI.
• The time-domain approach, utilizing oscillators for curvature compensation, simplifies design and enhances performance.
• This technology is suitable for cost-sensitive and space-constrained applications requiring precise thermal control.