Charge amplifiers

What is a charge amplifier?

In the field of measurement technology, a charge amplifier is essentially a charge converter that converts very low charge signals, as are generated, e.g., by piezoelectric sensors, to proportional voltage signals (volt).

    Are you still missing the right amplifier or data acquisition device for the upcoming measurement with your piezoelectric sensors? In this short video, Martin Stierli, Kistler specialist for DAQ & Signal Conditioning, explains how to choose the right device for you application.

    How does a charge amplifier function with piezoelectric sensors?

    The charge produced by a piezoelectric sensor is a quantity that is difficult to access. It is proportional to the load or to the applied pressure. Only after the invention of the first charge amplifier for piezoelectric signals by Walter P. Kistler in 1950 did the piezoelectric effect become commercially viable in measurement technology: a charge amplifier converts the negative charge output by the piezoelectric sensor in proportion to the applied pressure to a positive, proportional voltage. Modern charge amplifiers can also make this signal directly available in digital form.

    What needs to be taken into consideration when selecting the correct charge amplifier?

    There is a wide selection of charge amplifiers. The most important criteria when selecting the right charge amplifier are:

    • Number of measuring channels 
    • Measuring range: small or large charge signals
    • Measurement type: measurement with zero point reference (quasi-static) or purely dynamic (high-pass behavior)
    • Frequency range of the signals to be measured
    • Data use: analog or digital