A Temperature-to-Frequency Converter-Based On-Chip Temperature Sensor with an Inaccuracy of +0.65 °C/-0.49 °C

Area of Science:

• Integrated Circuits
• Sensor Technology
• Semiconductor Devices

Background:

• Accurate temperature sensing is crucial for various electronic systems.
• Existing sensors often face challenges with accuracy, resolution, and stability.
• CMOS technology offers a scalable platform for developing advanced sensors.

Purpose of the Study:

• To propose and validate a novel temperature sensor based on temperature-frequency conversion.
• To achieve high accuracy and resolution in temperature measurement using 180 nm CMOS technology.
• To minimize the impact of process variations and power supply fluctuations.

Main Methods:

• Design of a temperature sensor incorporating proportional-to-absolute temperature (PTAT) current generation.
• Implementation of two relaxation oscillators (OSC-PTAT and OSC-CON) for temperature-frequency conversion.
• Utilizing bipolar junction transistors (BJTs) as the core temperature sensing element.
• Employing voltage average feedback (VAF) to enhance oscillator frequency stability.

Main Results:

• The sensor operates within a 0-100 °C range with a post-calibration inaccuracy of +0.65 °C/-0.49 °C.
• Achieved a high resolution of 0.003 °C.
• Demonstrated a resolution Figure of Merit (FOM) of 6.7 pJ/K².
• The fabricated sensor occupies an area of 0.059 mm² and consumes 32.9 μW.

Conclusions:

• The proposed CMOS temperature sensor effectively utilizes temperature-frequency conversion for accurate measurements.
• The dual oscillator design and BJT sensing module contribute to high accuracy and resolution.
• The sensor's performance indicates its suitability for applications requiring precise temperature monitoring.