Nagel, J. H. “Biopotential Amplifiers.” The （内格尔,j . hu201D生物电势放大器。）.pdf

Nagel, J. H. “Biopotential Amplifiers.” The Biomedical Engineering Handbook: Second Edition. Ed. Joseph D. Bronzino Boca Raton: CRC Press LLC, 2000 70 Biopotential Amplifiers 70.1 Basic Amplifier Requirements Interferences 70.2 Special Circuits Instrumentation Amplifier • Isolation Amplifier and Patient Safety • Surge Protection • Input Guarding • Dynamic Joachim H. Nagel Range and Recovery • Passive Isolation Amplifiers • Digital University of Stuttgart Electronics Biosignals are recorded as potentials, voltages, and electrical field strengths generated by nerves and muscles. The measurements involve voltages at very low levels, typically ranging between 1 µV and 100 mV, with high source impedances and superimposed high level interference signals and noise. The signals need to be amplified to make them compatible with devices such as displays, recorders, or A/D converters for computerized equipment. Amplifiers adequate to measure these signals have to satisfy very specific requirements. They have to provide amplification selective to the physiological signal, reject superimposed noise and interference signals, and guarantee protection from damages through voltage and current surges for both patient and electronic equipment. Amplifiers featuring these specifications are known as biopotential amplifiers. Basic requirements and features, as well as some specialized systems, will be presented. 70.1