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A charge amplifier is a current integrator that produces a voltage output proportional to the integrated value of the input current. The amplifier offsets the input charge using a feedback reference capacitor, and produces an output voltage inversely proportional to the value of the reference capacitor but proportional to the total input charge flowing during the specified time period; hence the circuit acts as a charge-to-voltage converter. The gain of the circuit depends on the value of the feedback capacitor. ==Applications== Common applications include amplification of signals from such as piezoelectric sensors and photodiodes, in which the charge output from the transducer is converted into a voltage. Charge amplifiers are also used extensively in instruments measuring ionizing radiation, such as the proportional counter or the scintillation counter, where the energy of each pulse of detected radiation due to a ionising event must be measured. Integrating the charge pulses from the detector gives a translation of input pulse energy to a peak voltage output, which can then be measured for each pulse. Normally this then goes to discrimination circuits or a multi channel analyser. Charge amplifiers are also used in the readout circuitry of CCD imagers and flat-panel X-ray detector arrays. The objective is to measure the very small charge stored within an in-pixel capacitor. Advantages of charge amplifiers include: * Enables quasi-static measurements in certain situations, such as constant pressures on a piezo lasting several minutes * Piezo element transducer can be used in much hotter environments than those with internal electronics〔 * Gain is dependent only on the feedback capacitor, unlike voltage amplifiers, which are affected greatly by the input capacitance of the amplifier and the parallel capacitance of the cable〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Charge amplifier」の詳細全文を読む スポンサード リンク
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