An Ultra Low Power Bandpass Filter for Pacemaker

• Main Authors: Ｗei-chun Kao, 高維均
• Other Authors: Shuenn-yuh Lee
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/55936969824516400416

碩士 === 國立中正大學 === 電機工程所 === 97 === In this thesis, an ultra low power Gm-C bandpass filter for pacemaker was implemented. In order to approach the maximally flat in passband , the Butterworth topology was chosen in the filter system. Because the intracardiac frequency ranges from 10Hz to 70Hz, the upper and lower cutoff frequencies must conform to this range. In practical fulfillment, using KCL and KVL nodal analysis can improve the traditional elemental replacement, so that the number of elements used could be lowered down and the total power consumption could be reduced, too. Because the pacemaker is embedded inside the body, the power consumption is the first concern. Therefore, the operational transconductance amplifiers (OTAs) inside the filter are supplied by 1 V voltage and operated in the weak inversion to lower the power consumption. While implementing the OTA, the current cancellation was chosen to lessen the equivalent transconductance so that it could conform to the coefficient of the low-frequency analog filter. Besides, source degeneration was applied to increase its linearity. In this thesis, TSMC 0.35μm Mixed Signal 2P4M CMOS Process was used for the chip and its area was 0.104 mm2. According to the measured results under the 1 V supply voltage, the total power consumption is 12nW, THD is 1%, IMD3 is -42dB and SNDR is 26dB. Moreover, the wave could be detected by inputting pseudo heart signals.