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