A New Capacitance Multiplier Structure with High Multiplication Factor for Ultra-Low-Frequency Filter in Biomedical Applications*

摘要

A novel capacitance multiplier is proposed to implement an ultra-low-frequency filter for physiological signal processing in biomedical applications. With the proposed multiplier, a simple first-order low-pass filter achieves a -3-dB frequency of 33.4 mu Hz with a 1-pF capacitance and a 20 k Omega resistance. This corresponds to a multiplication factor of as large as 2.4 x 10(11). By changing the controlling terminal, the -3-dB frequency can be tuned in a wide range of 33.4 mu Hz-6.3 kHz.