Mixed-analog /digital Capacitive readout circuit for mechanical and Optical sensors

הרקע לפרויקט:

There are many types of sensors which change the value of a capacitor upon sensing a physical parameter, like pressure, fluid level, mechanical stress and other. This change in capacitance must be detected by a readout circuit, which can be either an analog circuit (analog to digital converter) or a digital circuit in some cases (like a frequency based converter).

מטרת הפרויקט:

In this project an analog/digital capacitance-to-digital readout circuit will be designed for mechanical sensors. These sensors are useful to measure a physical/mechanical parameter, such as pressure/vibration/acceleration/ ultrasound or optical excitation. The sensing capacitor is sensitive to the physical parameter and its capacitance changes linearly during the sensing. The interface circuit is based on two ring oscillators, which drive programmable capacitors. One of the capacitors is the sensing capacitor, while the second capacitor is a known reference capacitor. Each ring oscillator will generate a frequency, which is proportional to the capacitor which it drives. Several algorithms will be used to cancel the offset between the two ring oscillators. The result will be a digital word which is linearly proportional to the sensed parameter. It will be attempted to develop a novel circuit which is competitive with state-of-the-art sensors reported in the literature.

תכולת הפרויקט:

Students involved will survey the prior-art sensors and understand their performance level. After this, a ring oscillator sensor will be designed and simulated using virtuoso tools. The sensor will be compared to the state-of-the-art. An outstanding project may even be able to tape-out the sensor to achieve measured results. This project may lead to a journal publication and can be extended to a Master’s thesis.

קורסי קדם:

• 768330301 אלקטרוניקה לינארית - חובה
• 768332501 מעבדה למעגלים אנלוגיים – חובה
• 8330801 מעגלים אלקטרוניים ספרתיים – חובה
• 83315 מעבדה מעגלים אלקטרוניים ספרתיים – חובה
• 768361101 מעגלים משולבים אנלוגיים – מומלץ

דרישות נוספות:

a lot of motivation!!

מקורות:

1. “Capacitance-to-Digital Converter for Operation Under Uncertain Harvested Voltage down to 0.3V with No Trimming, Reference and Voltage Regulation” by Orazio AIELLO, Paolo CROVETTI and Massimo ALIOTO. International Solid State Circuits Conference 2020, pp. 74.