Liwei Lin (Advisor)

Research Advised by Professor Liwei Lin

Lin Group:  List of Projects | List of Researchers

Low Noise, Low Power Cavity Optomechanical Oscillators

Alejandro Griñe
Ming C. Wu
Liwei Lin
Constance Chang-Hasnain
2014

Cavity Optomechanical oscillators (OMOs) rely on photon radiation pressure to induce harmonic mechanical motion of a micron-scale light resonator. Unlike most oscillators, optomechanical oscillators require only CW input light without the need for electronic feedback and so hold promise for their novelty. In an optical cavity of sufficient quality factor, the transduction from photons to phonons can be quite efficient as we characterized optomechanical cavities which only required 17 microwatt input optical power to induce mechanical oscillation. The question then remains whether OMOs can...

FMCW Lidar: Scaling to the Chip-Level and Improving Phase-Noise-Limited Performance

Phillip Sandborn
Ming C. Wu
Bernhard Boser
Kristofer S.J. Pister
Liwei Lin
2017

Lidar (light detection and ranging) technology has the potential to revolutionize the way automated systems interact with their environments and their users. Most lidar systems in the industry today rely on pulsed (or, "time-of-flight") lidar, which has reached limits in terms of depth resolution. Coherent lidar schemes, such as frequency-modulated continuous-wave (FMCW) lidar, offer significant advantage in achieving high depth resolution, but are often too complex, too expensive, and/or too bulky to be implemented in the consumer industry. FMCW, and its close cousin, swept-source optical...

High-Q MEMS Capacitive-Gap Resonators for RF Channel Selection

Lingqi Wu
Clark T.-C. Nguyen
Tsu-Jae King Liu
Liwei Lin
2015

On chip capacitive-gap transduced micromechanical resonators constructed via MEMS technology have achieved very high Q’s at both VHF and UHF range, making them very attractive as on-chip frequency selecting elements for filters in wireless communication applications. Still, there are applications, such as software-defined cognitive radio, that demand even higher Q’s at RF to enable low-loss selection of single channels (rather than bands of them) to reduce the power consumption of succeeding electronic stages down to levels more appropriate for battery-powered handhelds. This...

Capacitive-Gap MEMS Resonator-Based Oscillator Systems for Low-Power Signal Processing

Thura Lin Naing
Clark T.-C. Nguyen
Ali Javey
Liwei Lin
2015

Wireless technology, which already plays a major part in our daily lives, is expected to further expand to networks of billions of autonomous sensors in coming years: the so-called Internet of Things. In one vision, sensors employing low-cost, low-power wireless motes collect and transmit data through a mesh network while operating only on scavenged or battery power. RF MEMS provides one approach to the stringent power and performance required by sensor networks.

This dissertation presents improvement to these MEMS technologies and introduces new approaches for wireless...

Interface Electronics for Ultrasonic Transducers

Hao-Yen Tang
Bernhard E. Boser
David A. Horsley
Liwei Lin
2016

Ultrasound has long been used for medical imaging. Recent advances of miniaturized MEMS ultrasonic transducers new applications such as gesture recognition, personal fitness devices, and fingerprint sensors. These devices are considerably smaller than conventional transducers. To benefit from their lower excitation power requirements and address the reduced sensitivity requires the design of novel interface electronic circuits.

The first part of this thesis describes new circuits capable of generating all the high voltage drive signals for MEMS transducers on-chip from a single low...

Roseanne Warren

Alumni
Mechanical Engineering
Professor Liwei Lin (Advisor)
Ph.D. 2015

High-Q AlN Contour Mode Resonators with Unattached, Voltage-Actuated Electrodes

Robert Schneider
Clark T.-C. Nguyen
Kristofer S.J. Pister
Liwei Lin
2015

High-Q narrowband filters at ultra-high frequencies hold promise for reducing noise and suppressing interferers in wireless transceivers, yet research efforts confront a daunting challenge. So far, no existing resonator technology can provide the simultaneous high-Q, high electromechanical coupling (k2 ), frequency tunability, low motional resistance (Rx), stop band rejection, self-switch ability, frequency accuracy, and power handling desired to select individual channels or small portions of a band over a wide RF range. Indeed, each technology...

Kisik Koh

Alumni
Mechanical Engineering
Professor Liwei Lin (Advisor)
Ph.D. 2015

Shiqian Shao

Alumni
Mechanical Engineering
Professor Liwei Lin (Advisor)
Ph.D. 2016

Sina Akhbari

Alumni
Mechanical Engineering
Professor Liwei Lin (Advisor)
Ph.D. 2016