| has gloss | eng: A charge amplifier is an amplifier whose equivalent input impedance is a capacitive reactance that is very high at low frequencies. Thus contrary to what its name may suggest, a charge amplifier does not amplify the electric charge present at its input. Its function is actually to obtain a voltage proportional to that charge and yield a low output impedance. Hence it is a charge-to-voltage converter. Common applications include piezoelectric sensors and photodiodes, in which the charge output from the transducer is converted into a voltage. Charge amplifiers are often found in instrumentation, and in the readout circuitry of CCD imagers and flat-panel X-ray detector arrays. In read-out circuits the objective is usually to measure the very small charge stored within an in-pixel capacitor, despite the capacitance of the circuit-track to the readout circuit being a couple of orders of magnitude greater than the in-pixel capacitor. |
