Title page for ETD etd-1110103-174217


Type of Document Master's Thesis
Author Kopparthi, Sunitha
Author's Email Address skoppa1@lsu.edu
URN etd-1110103-174217
Title Remote Power Delivery and Signal Amplification for MEMS Applications
Degree Master of Science in Electrical Engineering (M.S.E.E.)
Department Electrical & Computer Engineering
Advisory Committee
Advisor Name Title
Pratul K Ajmera Committee Chair
Ashok Srivastava Committee Member
Martin Feldman Committee Member
Keywords
  • signal amplification
  • MEMS applications
  • remote power delivery
Date of Defense 2003-10-21
Availability unrestricted
Abstract
Device such as remotely located sensors and bio-implanted devices such as gastric pacer require power for operation. The most commonly used energy source for such devices is a battery cell included in the receiver capsule. Wires can also be used with an external power source but in some applications have serious limitations. This work examines a wireless power transmitter and receiver system to provide power to a remotely located microsystem. Inductive power coupling is the method of choice.

For gastric pacer application, external transmitter coil can be worn around the waist as a belt and the receiver coil can be a part of a remotely located bio-implanted system. The coupling between transmitter and receiver coils when the diameters are markedly different is analyzed. A conventional rectifier circuit converts ac voltage to required dc voltage. This dc voltage supplies power to the charging chip, which is used to recharge lithium batteries in the implanted system. For an input supply voltage of 0.35 Vrms, the induced voltage in the receiver coil across the load resistor was 0.37 Vrms, when the receiver coil was placed at the center of the transmitter coil. When the receiver coil was placed close to the rim of the transmitter, the induced voltage across the load resistor for the same input supply voltage was 0.67 Vrms. Corresponding transmitted power to the load resistor of the receiver coil were 4 and 13.2 mW, respectively. Means are suggested to improve the power transfer to the receiver coil.

The second objective of this thesis is to design an op-amp for on-chip amplification of sensor signals. On-chip detection and amplification are crucial for obtaining high sensitivity and improved signal to noise ratio. Designed op-amp is simulated using PSPICE with Level-3 MOS model parameters. The simulation results show a gain of 40.7 dB and a 3-dB bandwidth of 580 kHz. Experimental measurements made on the fabricated chip observed a gain of 3 and a 3-dB bandwidth of 1 MHz, which was attributed to differences in the values of simulated model parameters and the values appropriate for the fabrication process used by the foundry.

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