Circuit comprising an input means comprising a multiplexer being configured to selectively forward a current from a current source out of a plurality of current sources; a cross-multiplexer; a differential capacitive transimpedance amplifier having a first capacitance and a first switching element connected in parallel to the negative input port and a first output port of the differential capacitive transimpedance amplifier and a second capacitance and second switching element connected in parallel to the positive input port and a second output port of the differential capacitive transimpedance amplifier; a first output port of the cross-multiplexer being connected to the negative port of the differential capacitive transimpedance amplifier and the second output port of the cross-multiplexer being connected to the positive port of the differential capacitive transimpedance amplifier; the cross-multiplexer being configured either to establish a first current path between its first input port and its first output port and a second current path between its second input port and its second output port in direct mode or to establish a first current path between its first input port and its second output port and a second current path between its second input port and its first output port in reverse mode; the cross-multiplexer being further configured to operate in direct mode and the first and second switching elements are off so as to integrate a first current flowing into the first and second capacitance; and if a second current is to be added to the first current, the input means is configured to receive the second current, the cross-multiplexer is configured to operate in direct mode, and the first and second switching elements are off so as to integrate the second current flowing into the first and second capacitance; and if a second current is to be subtracted from the first current, the input means is configured to receive the second current, the cross-multiplexer is configured to operate in reverse mode, and the first and second switching elements are off so as to integrate with reverse polarity the second current flowing into the first and second capacitance; the circuit further comprising a first current mirror with mirror ratio m; a second current mirror; a third current mirror; the input means being connected to the input port of the first current mirror; the output port of the first current mirror being connected to the input ports of the second and third current mirror; the output port of the second current mirror being connected to the first input port of the cross-multiplexer; the output port of the third current mirror being connected to a second input port of the cross-multiplexer; and the first current mirror being tunable with respect to the factor m and a tunable integration time t i for each individual current to achieve a desired gain G with an integration capacitance C int according to G = t i ⋅ m C int; the first capacitance and the second capacitance being tunable devices or digitally programmable capacitance sub-circuits. a first capacitance and a first switching element connected in parallel to the negative input port and a first output port of the differential capacitive transimpedance amplifier and a second capacitance and second switching element connected in parallel to the positive input port and a second output port of the differential capacitive transimpedance amplifier; a first output port of the cross-multiplexer being connected to the negative port of the differential capacitive transimpedance amplifier and the second output port of the cross-multiplexer being connected to the positive port of the differential capacitive transimpedance amplifier; the cross-multiplexer being configured either to establish a first current path between its first input port and its first output port and a second current path between its second input port and its second output port in direct mode or to establish a first current path between its first input port and its second output port and a second current path between its second input port and its first output port in reverse mode; if a second current is to be added to the first current, the input means is configured to receive the second current, the cross-multiplexer is configured to operate in direct mode, and the first and second switching elements are off so as to integrate the second current flowing into the first and second capacitance; and if a second current is to be subtracted from the first current, the input means is configured to receive the second current, the cross-multiplexer is configured to operate in reverse mode, and the first and second switching elements are off so as to integrate with reverse polarity the second current flowing into the first and second capacitance; the output port of the first current mirror being connected to the input ports of the second and third current mirror; the output port of the second current mirror being connected to the first input port of the cross-multiplexer; the output port of the third current mirror being connected to a second input port of the cross-multiplexer; and