Research Experience

  • Design of DC Offset Calibration Techniques in Homodyne/Heterodyne Receivers
    • Devised a coarse-tuning DC calibration method at the RF front-end using RF signal inverse compensation. This technique allows the baseband to be DC coupled so as to preserve all the information.
    • Devised DC coupled baseband fine-tuning architecture to relieve the amplifiers from saturation and reach the maximum dynamic range.
    • Designed wireless DC tuning hardware system based on wireless ZigBee communication.

    • (a) Block diagram of the receiver with RF and baseband DC calibration architectures

    • (b) DC calibration setup

    • (c) Before and after DC calibration

  • System Design of K-band 24 GHz Microwave Sensor for Micro-Vibration Sensing
    • Devised a miniature high-sensitivity K-band microwave transceiver for radar sensor system with homodyne quadrature I/Q architecture.
    • Devised the power management unit for the transceiver using various DC-DC and LDO chips.
    • Designed micro-strip Wilkinson power divider and 24 GHz patch antennas array.
    • Analyzed link budget and noise figure for experimental comparison with other radars.

    • (a) 24 GHz Microwave Sensor

    • (b) Simulated S11, 24 GHz antenna array

    • (c) Radiation pattern

    • (d) Link budget and noise figure analysis

  • System Design of S-band RF Transceiver for 2.4 GHz Radar sensor
    • Designed a software-defined RF transceiver for radar sensor system using commercial ICs on Rogers 4350B RF laminate. The radar transceiver includes CPW transmission line, LNA, gain block, filter, quadrature demodulator, etc.
    • Developed Ray Tracing model in MATLAB for simulation of radar measurement based on nonlinear phase modulation.

    • (a) 2.4GHz, seperate RF & BB

    • (b) 2.4 GHz, stacked

    • (c) with ZigBee wireless transmission

    • (d) Ray Tracing analysis

  • Design of Active RF Transponders in Radar System
    • Designed an active RF transponder that receives 2.4 GHz and transmits 3.3 GHz to boot signals and reject clutters reflected from surrounding objects.
    • Designed an ISM band RF transponder utilizing single-sideband modulation technique. The system works in a novel heterodyne architecture to isolate the tagged object from clutters.

    • (a) Block diagram

    • (b) Experimental setup in lab

  • Baseband Development for RF Transceiver System
    • Designed LabView platform to interface with ZigBee and for real-time signal processing.
    • Developed codes for MSP430 microcontroller I/Q data acquisition and signal encoding/decoding.
    • Developed Radar sensors meshing network based on ZigBee protocols using XBee modules.

    • (a) Designed LabVIEW program


  • Instruments familiarity
    • Developed an instruments-based Doppler radar system with digital-IF super-heterodyne architecture for vital sign detection.

    • (a) Block diagram of the digital-IF super-heterodyne system

    • (b) Instruments-based of the digital-IF super-heterodyne system

  • Wireless sensing for capacitive sensors

    • (a) Wireless capacitive sensor measurement based on Chirp signal