Sensor Interface Circuit Design towards CMOS Scaling
Sensor interface circuit design is critical in building a low-power, low-cost smart sensors device. While digital circuits directly benefit from scaled CMOS technology because of smaller transistor and lower supply voltage, analog and mixed signal circuit design faces more challenges due to reduced signal amplitude, loss of intrinsic gain, and more expensive passive components. One effective way to exploit scaled CMOS in front-end circuit design is switched-capacitor circuits. However, continuous time anti-aliasing filter (CTAAF) is needed before sampling operation in the mixed-signal chain. By adopting windowed integration sampling (WIS), the CTAAF in the mixed-signal conditioning front-end can be eliminated without severe noise aliasing effects. The closed-loop structure further improves the linearity and enables the transfer function to be set by precision capacitor ratios. On the other hand, sigma-delta modulator (SDM) can efficiently convert the higher ! time resolution of scaled CMOS into dynamic range. Directly interfacing sensor with SDM reduces the analog blocks in front-end design, making it more scalable with CMOS technology. To further improve the power efficiency for wireless sensor applications, compressive sensing (CS) can be embedded into SDM to reduce the data rate of the front-end and thus save the digitizing power and wireless transmitting power. The signal recovery can be achieved at the back-end with the ever-growing computation power thanks to CMOS scaling. Block diagonal matrix is designed to improve the area efficiency by reusing the modulators. By exploiting the similar sparse signatures across the channels in multi-channel recording applications, modified recovery algorithm improves the recovered signal-to-error ratio (SER) that can otherwise be compromised by increased coherence between sensing matrix and sparse representation matrix.
Major Advisor: David J. Allstot
Committee: Matthew Johnston
Committee: Gabor C. Temes
Committee: Raviv Raich
GCR: Megumi Kawasaki
Friday, October 30 at 10:00am to 12:00pmVirtual Event