Chip-scale Microsystems for Radio Frequency Signal Processing

 

RF Photonics Devices and Microsystems

 

Wireless Microsystems for Implantable and Wearable Electronics

 

Multi-modality Resonant Sensors

 

Micromachining, heterogeneous integration methods, and layer transfer techniques

Chip-scale Programmable RF Filtering and Synthesis

In this thrust, our group develops chip-scale programmable RF filtering and synthesis platforms in response to the increasing demand for frequency-agile, and function-dynamic RF front ends, a “holy grail” problem currently in the field. Our approach features a multitude of chip-scale micro-electro-mechanical systems operating in RF, and microwave frequency ranges. These devices include piezoelectric MEMS resonators and tunable reactive elements. Specifically, a new class of piezoelectric MEMS resonators, dubbed as Lithium Niobate laterally vibrating resonators (LN LVRs), is being optimized and applied to RF applications. LN LVRs harness the high electromechanical coupling of the LN material and have lithographical defined center frequencies. They also have the highest FoM in comparison to state of the art. These devices are being used by our group as the fundamental circuit-level building blocks for reconfigurable frequency synthesis and filter platforms, in the hope of translating their superior device-level performance into unprecedented capabilities of in-field adaptation to RF ambiance on the system-level. In addition to introducing programmability to filtering, we also aim to overcome several remaining roadblocks in the path of commercializing LN LVRs for the marketplace. Specifically, mitigation of spurious modes, Q enhancement, and increase of power handling and linearity are being investigated.

Passive Front-end Microsystems for Wakeup Radios

In this area, my group develops passive microsystems for low-power RF transceivers that remain dormant and can be waked-up by an extremely faint signal. Such wake-up radios are a technological strategy to reduce the power consumption of battery-powered things (IoT) with wireless connectivity and long latency between functioning periods. One of the major hurdles for such technology platforms is to trigger upon the low power signal that has an amplitude significantly below the threshold voltages of state of the art semiconductor or alternative MEMS devices. Another challenge is to incorporate high frequency selectivity to avoid false wake-up caused by interference signals in the RF spectrum. To address these challenges, our research promises a solution that utilize piezoelectric passive voltage amplification with enhanced efficiency and frequency selectivity, prior to the signal processing by RF back-ends.

Non-reciprocal RF Devices and Components

On this topic, we work on new microsystems that have non-reciprocal response for RF-front ends. The non-reciprocity is achieved by leveraging new materials, novel devices designs, and the understanding of parametric and nonlinearity effects. The goal of the research is to demonstrate devices with a small form factor, high power handling, near zero power consumption, and large fractional bandwidth simultaneously. More details to come on the development, please check out publication page for more recent progress on this topic.

RF Photonics Devices and Microsystems

In this area, my group develops passive microsystems for low-power RF transceivers that remain dormant and can be waked-up by an extremely faint signal. In this direction, an RF photonic front-end module based on acousto-optic and electro-optic devices is envisioned to yield compact, high performance, and ultra-wide bandwidth system. The rationale behind hybridizing RF-acoustics with photonics is to harness the best of both acoustic and photonic domains for signal processing at RF. Specifically, the lower loss propagation of lightwave and high sensitivity detection of photons are to be leveraged for RF functionalities that cannot be attained using conventional RF devices alone. For this topic, we are interested in collaboration on monolithically integrated light sources on non III-V substrates, or other intimate heterogeneous integration schemes that offer high performance and small form factor. For more recent process, please see our publication page.

Wireless Microsystems for Implantable and Wearable Electronics

Our research also starts to develop RF front ends for biomedical implants, hardware assurance, and wearable electronics with wireless connectivity. The motivation behind this thrust is to integrate advancements of RF technology into medicine, security, and wearables, consequently allowing powering and communication with devices and component that are otherwise inaccessible and prohibitively difficult to engage. These systems share the similarity of involving a miniature platform that is power constrained and size specific. The communication and powering in our designs typically share a near field link and transceivers on both ends typically operate in the vicinity of each other. We are looking for collaborators to extend our designs to broader range of applications in medicine and wearables.

Multi-modality Resonant Sensors

For our effort targeting various sensing applications, we apply our expertise in engineering chipscale resonant systems to a wide range of sensing modalities, including infrared, electric, and magnetic fields. The resonant sensors developed in our group often leverage the resonance phenomenon in electromagnetic (from RF to optical), mechanical, or simultaneously both domains to enhance the responsivity, reduce the size, squeeze the noise, and ensure room temperature operation. The implementation of our designs ranges from single devices for point detection to small arrays for focal planes.

Micromachining, heterogeneous integration methods, and layer transfer techniques

We have a constant interest in developing novel micro-machining techniques for enabling devices with new structures, novel configurations, and emerging materials. These techniques are considered as a path way to higher performance in a bottom-up approach. Similariy for this purpose, we also work on heterogeneous integration methods to enable “microsystems + X” modules that combine the technical benefits of microsystems and platform X (e.g. III-V, IPDs, or CMOS). The intimate integration of both or more is critical in achieving unprecedented system-level performance at radio and microwave frequencies.

Research Sponsors

 

 

 

Research Collaborators

The interdisciplinary nature of our research benefits greatly from the many collaborations we have with the top scholars and engineers in the relevant fields. The list below includes the principle investigators with whom we have worked closely on recent projects.

Prof. Daniel Shoemaker in Department of Material Science and Engineering at University of Illinois.
We collaborate on the development of RF devices using novel materials.

Prof. Dan Wasserman in Department of Electrical and Computer Engineering at University of Texas at Austin.
We collaborate on the development of Mid IR detectors based on MEMS resonators and metamaterials.

Prof. Xiuling Li in Department of Electrical and Computer Engineering at University of Illinois.
We collaborate on the development of integrated passive elements for RF and mmW applications.

Prof. Brian Cunningham in Department of Electrical and Computer Engineering at University of Illinois.
We collaborate on the development of RF-MEMS-enabled tunable photonic crystals.

Prof. Gianluca Piazza in Department of Electrical and Computer Engineering at Carnegie Mellon University.
We collaborate on the development of vicinity-based wireless communication and charging for chiplets.

Prof. Steven Bowers in Department of Electrical and Computer Engineering at University of Virginia.
We collaborate on the development of near zero power wakeup radios.

Prof. Scott Barker in Department of Electrical and Computer Engineering at University of Virginia.
We collaborate on the development of near zero power wakeup radios.

Prof. Benton Calhoun in Department of Electrical and Computer Engineering at University of Virginia.
We collaborate on the development of near zero power wakeup radios.

Prof. Charles Yu in Illinois Eye and Ear Infirmary at University of Illinois at Chicago.
We collaborate on the development of implantable RF devices.