This thesis is concerned with the study and design of three integrated filters for biomedical applications. The following designs are considered: A 2nd-order high-pass filter with low cut-off frequency (Design 1), a 2nd-order low-pass filter with high cut-off frequency (Design 2), and a 1st-order high-pass filter with low cut-off frequency (Design 3). Design 1 and 2 are intended for separating the physiological signal and a high-frequency test signal in the application of a chip safety monitoring system. Design 3 finds its application in a system for adaptive sampling of the electrocardiogram. The details of the applications are not part of this thesis.
Design 1 is composed of operational transconductance amplifier (OTA) and capacitances. The thesis adopts an 2nd-order fully-differential HP filter and uses conventional folded-cascode OTAs to realize the fully-differential HP filter. By proper designing the transistor sizes of the OTA, the HP filter can achieve specific specification in
our biomedical system. Its post-layout simulated cut-off frequency is 316 kHz and the total harmonic distortion is -40.14dB with a 1MHz 2 Vp-p input signal.
Design 2 is also composed of OTA and capacitances. To overcome the linearity problem of OTA, so-called symmetrical and asymmetrical differential pairs are utilized to design a more linear transconductor. Moreover, a conventional gate voltage-controlled negative resistor circuit with CMFB circuit is used to create the required high output
impedance of the OTA. The CMFB circuits are used to stabilize the output dc level in the OTA. The OTA is used to realize a fully-differential 2nd-order LP filter. By proper designing the transistor sizes of the OTA, the filter can achieve specific specification in our biomedical system. The filter¡¦s post-layout simulated cut-off frequency is 12.93 MHz and the total harmonic distortion is -47.14 dB with a 10 MHz 1 Vp-p input signal.
Design 3 uses an RC filter design with bulk-drain connected MOS transistors biased as an active high-value resistor. A cut-off frequency of 647 Hz is thus achieved on an active area of 0.012 mm2.
Test chips were fabricated in TSMC 0.35 £gm CMOS technology for Designs 1 and 3 and the measured results are reported, confirming the operation of the filters.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0809110-132126 |
| Date | 09 August 2010 |
| Creators | Nian, Shu-Han |
| Contributors | Jih-Ching Chiu, Chua-Chin Wang, Robert Rieger, Ya-Hsin Hsueh |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0809110-132126 |
| Rights | not_available, Copyright information available at source archive |
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