A Self-Calibrated Ultra Low-Power Band-Pass Filter for ECG Acquisition Systems

• Main Authors: Kuang-hui Wang, 王光輝
• Other Authors: Tsung-Heng Tsai
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/06200665114101446328

碩士 === 國立中正大學 === 電機工程所 === 98 === This paper presents an ultra low-power self-calibrated band-pass filter suitable for processing electrocardiogram (ECG) signals. The pass-band frequency is between 3Hz to 125Hz. The realization of this filter is continuous-time operational transconductance amplifier-C (OTA-C) architecture. Considering maximally flatness in the pass band, Butterworth topology was chosen. However, for an OTA-C filter implementation, such low frequencies often imply large time constants. While implementing the OTA, operated in weak inversion, current cancellation and current division were applied to decrease the equivalent transconductance; at the same time, possibly reduce the value of the capacitors, and minimize the area to consume. Besides, source degeneration was applied to increase its linearity. A mathematic analysis for the noise of the proposed OTA was also presented. The self-calibration is carried out by utilizing a PLL to alleviate P.V.T. variation. This filter was fabricated in a TSMC 90nm CMOS Mixed Signal RF Low Power Low-K Cu 1P9M 1.2&2.5V Standard Process. The active area is 0.14mm2. Measurement results show that the fourth-order band-pass filter operates at 1-V power supply and consumes 120 nW of power, with a dynamic range greater than 42.5dB. The total pass-band input-referred- noise is 70.3 μVrms.