Such a circuit arrangement is described for example in Finvers et al.: “A High Temperature Precision Amplifier”, IEEE Journal of Solid-State Circuits, Vol. 30, No. 2, February 1995, pages 120-128. Operational amplifiers in amplifier circuits are usually connected up in such a way that a voltage between the inputs of the operational amplifier is ideally zero. If the operational amplifier is beset with an offset, then an offset voltage not equal to zero is established between the inputs of said operational amplifier, which leads to a corruption of the measurement result. In such circuits, the offset compensation arrangement serves to detect such an offset voltage present between the inputs of the operational amplifier and to generate an offset compensation signal. Said compensation signal is fed to an offset compensation input of the operational amplifier in order to regulate the offset voltage between the inputs of the operational amplifier to zero.
This offset compensation by detecting the input voltage of the operational amplifier and generating the compensation signal depending on the input voltage may lead to problems when a frequently changing input signal is fed to the operational amplifier. This is because, in the event of a level change of the input signal, the input voltage difference of the operational amplifier is initially not zero until the operational amplifier has again attained a settled state. This input voltage difference not equal to zero is registered as an offset by the offset compensation arrangement and incorrectly leads to a change or adaptation of the compensation signal.
Offset compensation arrangements usually have an integrating behavior, which has the effect that the offset compensation signal increases with the number of level changes of the input signal or with the number of settling operations of the operational amplifier. The consequence of this is that the operational amplifier is “overcompensated”, so that precisely during the settled state of the operational amplifier there is an offset present which increases as the number of level changes of the input signal increases or as the number of settling operations of the operational amplifier increases.
It would therefore be advantageous to provide a circuit arrangement having an amplifier arrangement—which has an operational amplifier—and having an offset compensation arrangement which does not have these disadvantages.