Research

The intellectual focus of our research group is on:

  • Analog, mixed-signal, and RF integrated circuits;
  • Miniature spin resonance systems;
  • Micro- and nanoscale solid-state platforms as an electrical, electrochemical, and optical analytical tool for biotechnology and medicine;
  • Low-cost medical imaging systems.

Our ongoing research projects include:

1. Analog and Mixed-Signal IC Design

We are developing high-performance analog/mixed-signal circuits and architectures. Our research efforts focus primarily on designing low-power, high-speed, and high-resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). We investigate a wide range of ADC and DAC architectures, including pipelined, delta-sigma, and SAR. Our expertise lies in digital background calibration techniques and mismatch shaping techniques.

Recently, we have been very interested in time-domain (TD) analog signal processing (ASP) techniques using voltage-controlled oscillators. Such a TD-ASP framework suits well with nanometer-scale CMOS technology. Unlike conventional voltage-domain ASP approaches that suffer from reduced power supply voltages and smaller transistor intrinsic gains, TD-ASP takes advantage of the increased transistor speed and timing resolution brought by CMOS scaling.

2. Miniature Nuclear Magnetic Resonance Systems

We develop novel miniature nuclear magnetic resonance (NMR) systems by combining the physics of NMR with CMOS radio-frequency ICs. One example is a 0.1-kg ‘palm’ NMR system (shown in figure) that is 1200 times smaller, 1200 times lighter, yet 150 times more spin-mass sensitive than a state-of-the-art 120-kg commercial benchtop NMR system. This small NMR system can be used for disease detection and medical diagnostics. It was demonstrated capable of detecting human cancer cells and cancer marker proteins. This research has been featured in a number of articles, such as:

Palm Book Palm NMR

We are currently exploring several new directions, including:

  1. Miniature NMR systems for fluid and porous rock analysis for petroleum applications;
  2. Low-cost high-precision fully-integrated NMR magnetometers;
  3. Small magnetic resonance imaging (MRI) systems;
  4. Low-noise general-purpose NMR probes;
  5. NMR systems with dynamic nuclear polarization.

3. Silicon-Bio Interface

We are highly interested in using CMOS ICs to analyze biological systems in direct interface with them. We envision that such interfaces between solid-state circuits and biological systems can be very useful in biology and biotechnology. We are currently investigating:

  • Silicon-bio interface that can detect protein & DNA molecules via electrical or magnetic coupling;
  • Silicon-neuron interface that can simultaneously record and excite neuronal activities of a large ensemble of neurons with high spatiotemporal resolution.