digital-brain/content/zettels/charge_amplifiers.md

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+++ title = "Charge Amplifiers" author = ["Thomas Dehaeze"] draft = false +++

Tags
[Electronics]({{< relref "electronics" >}})

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="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="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
L-Card Rusia

Bibliography

Fleming, A.J. 2010. “Nanopositioning System with Force Feedback for High-Performance Tracking and Vibration Control.” IEEE/ASME Transactions on Mechatronics 15 (3):43347. https://doi.org/10.1109/tmech.2009.2028422.

Schmidt, R Munnig, Georg Schitter, and Adrian Rankers. 2014. The Design of High Performance Mechatronics - 2nd Revised Edition. Ios Press.