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+++ title = "Charge Amplifiers" author = ["Dehaeze Thomas"] draft = false category = "equipment" +++
- Tags
- [Electronics]({{< relref "electronics.md" >}})
Description
A charge amplifier outputs a voltage proportional to the charge generated by a sensor connected to its inputs.
This can be typically used to interface with piezoelectric sensors.
Basic Circuit
Two basic circuits of charge amplifiers are shown in Figure 1 (taken from (Fleming 2010)) and Figure 2 (taken from (Schmidt, Schitter, and Rankers 2014))
{{< figure src="/ox-hugo/charge_amplifier_circuit.png" caption="<span class="figure-number">Figure 1: Electrical model of a piezoelectric force sensor is shown in gray. The op-amp charge amplifier is shown on the right. The output voltage \(V_s\) equal to \(-q/C_s\)" >}}
{{< figure src="/ox-hugo/charge_amplifier_circuit_bis.png" caption="<span class="figure-number">Figure 2: A piezoelectric accelerometer with a charge amplifier as signal conditioning element" >}}
The input impedance of the charge amplifier is very small (unlike when using a voltage amplifier).
The gain of the charge amplified (Figure 1) is equal to: \[ \frac{V_s}{q} = \frac{-1}{C_s} \]
Manufacturers
| Manufacturers | Country |
|---|---|
| PCB | USA |
| HBM | Germany |
| Kistler | Swiss |
| MMF | Germany |
| DJB | UK |
| MTI Instruments | USA |
| Sinocera | China |
| Physimetron | Germany |