Time Constant Resistor

What is a time constant resistor and what does this resistor affect?

Many charge amplifiers allow different types of measurements. Basically, there are two measurement types: dynamic or quasi-static measurements. The decisive component for this is the time constant resistor. This time constant resistor together with the range capacitor  defines the characteristic of the time constant. The time constant in turn defines the behavior of the charge amplifier in the lower frequency range.

The graphic displays shows the time constant resistor integrated into the circuit diagram of a charge amplifier.
Circuit diagram of a charge amplifier with built-in time constant resistor Rt.

In simple terms, the time constant resistance determines whether a low-frequency measurement signal can be acquired – which corresponds to a quasi-static measurement – or whether only higher-frequency signal components can be measured. The latter corresponds to the 'dynamic' measurement type.