Sub-Nyquist Signal Acquisition Systems

CMOS Receiver for Compressive Sensing

As signals in the physical world are ultimately analog in nature, analog-to-digital converters (ADCs) are a key enabling technology for this trend. However, ADC speed and resolution have not kept pace with the stunning improvements in computing power, thus creating a bottleneck which limits the performance and application space of advanced signal processing techniques in physical systems.

Circuits for Biological and Medical Systems

Retinal Prosthesis

Most progressive vision loss occurs when the first layer of the retina (the photoreceptors) is damaged. Retinal prostheses aim to restore vision by bypassing the damaged photoreceptors and directly stimulating the remaining healthy neurons. Our approach uses highly scaled technologies to reduce area and power, and to support hundreds of channels for fully intraocular implants.

Origami Biomedical Implants

Origami implant design is a 3D integration technique which addresses the size and cost constraints in biomedical implants. Large systems can be split into multiple chips and connected using 3D integration techniques to be folded compactly for implantation and unfolded inside the body. Electronics can be partitioned into functional blocks for mass-production and customs implants can be assembled from these relatively cheap modules.

All-Digital Clock and Data Recovery

As data rates increase, process, voltage and temperature variations cause sufficient phase mismatch between signal paths to require per-pin phase alignment – even in source-synchronous systems. This project involves the development of a novel all-digital clock and data recovery technique for per-pin phase adjustment in high-density, high-performance serial interconnect.

Low-Power Optical Interconnects

The negligible frequency dependent loss of optical channels provides the potential for optical links to fully leverage increased data rates provided through CMOS technology scaling without excessive equalization complexity. A compact low-power optical receiver has been designed to explore the potential of optical signaling for future chip-to-chip and on-chip communication.

Ultra-Low-Power Equalization and Crosstalk Cancellation

The increasing demand for high bandwidth interconnection between integrated circuits requires large numbers of I/Os per chip as well as high data rates per I/O. Key limitations in meeting these requirements include channel characteristics and I/O power consumption. Using receiver and transmitter equalization can greatly improve the link performance.

PTAT Temperature Sensor for Micro-Ring Resonator Stabilization

As the resonance wavelength of micro-ring modulators is susceptible to temperature fluctuations, they require thermal tuning. The power consumed by wavelength stabilization circuitry is often higher than the transmitter itself. In this project a monolithic PTAT temperature sensor is proposed for low-power thermal stabilization of micro-ring resonator modulators through direct measurement of temperature.

Differential Ring Modulator

In design of Micro-ring modulators it is desirable to have high-Q rings since for a given extinction ratio a higher Q results in better energy efficiency. However, there is a trade-off between the Q of the ring resonator modulator and its optical bandwidth. In this project we propose a new structure is proposed that breaks the optical bandwidth/quality factor trade-off known to limit the speed of high-Q micro-ring modulators. This structure, called the “differential ring modulator”, maintains a constant energy in the ring to avoid pattern-dependent power droop.