頁籤選單縮合
題名 | High Input Impedance Circuits for Electrophysiological Signal |
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作者 | Jaw,Fu-Shan; Wang,Cheng-Yi; Lin,Chii-Wann; | 書刊名 | 醫學工程 |
卷期 | 6:6 1994.12[民83.12] |
頁次 | 頁865-868 |
分類號 | 410.01336 |
關鍵詞 | Instrumentation amplifier; Guard drive; Cascade source follower; Capacitance neutralization; |
語文 | 英文(English) |
英文摘要 | For reducing loading effect and motion artifice, high-input impedance is an essential requirement for biopotential amplifers. The input bias network of an amplifier will decrease the input impedance significantly. The effective capacitors from the recording electrode, the shielding cables, and the amplifier will decrease the input impedance of the amplifier at higher frequency. Therefore, in this paper, several techniques to compensate these effects have been reviewed. Firstly, the technique of low-gain direct couple with reduced negative feedback is used to eliminate the input bias network of amplifiers. Hence, very high input impedance can be achieved. Secondly, guard drive, cascade source follower, and capacitance neutralization are used to compensate the capacitors of the shielding cables, the amplifier, and the microelectrode, respectively. Thus, the input impedance of the amplifier will not be degraded at the frequency range of the signals. |
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