The Biosensor for Detecting Magnetic Beads and the Ultra Wideband VGA with Dual DC Offset Cancellation

• Main Authors: Cheng-Jiun Hsieh, 謝丞俊
• Other Authors: 呂學士
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/40660494401692920232

碩士 === 國立臺灣大學 === 電子工程學研究所 === 99 === This thesis proposes two major subjects: The biosensor for detecting magnetic beads and the ultra wideband VGA with dual DC offset cancellation. The biosensor for detecting magnetic beads is used for detect antigen in fluid. It can detect many antigen like HIV, DNA, and H1N1 virus just if we have the same type magnetic beads. This system is using the characters of magnetic beads to replace the tradition way detection in clinic (ELISA). The advantages of this biomedical system are easy-to-use, low-cost, and mobility. The system contains: two Hall sensor arrays, Chopper DDA and LPF. Besides, this system adds the coil to generate polarization field to reach the goal of lab-on-chip. Variable gain amplifier (VGA) plays an essential role in receivers by controlling the input signal’s magnitude and normalizing the average amplitude of the signal to a proper level. This system contains: four stages VGA, two DC offset cancellation loop, and output matching and buffer for measurement propose. One DC offset cancellation loop is used to DC offset cancel. The other loop is used to extend bandwidth without inductor picking. In that way, VGA in ultra wideband system reach the goals of wide bandwidth, low power consumption, small-area, and larger gain tuning range.