| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a charge amplifier and a charge amplifier device capable of reducing easily measuring drift, and a bias current compensation method capable of compensating easily an influence of a bias current Ib. <P>SOLUTION: The charge amplifier 101 converts input charge from a piezoelectric sensor Sn into an output voltage determined by dividing it by a capacitance C1e of a capacitor C1. When a bias current Ib flows, the sum of a bias charge determined by time-integrating the bias current Ib and the input charge is converted as the output voltage. Since the output voltage is influenced by the bias current Ib, the measuring drift is generated. A compensation current Ia flows wholly as the bias current Ib into an inverting input terminal (-) through a capacitor C2 into which an application voltage Va is applied. The charge amplifier 101 converts only the input charge into the output voltage. Hereby, the measuring drift is reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT |
