A touch-sensitive apparatus for determining positions of touches, comprising: a touch surface circuit including a touch surface and a plurality of drive electrodes and receive electrodes, each of the plurality of electrodes being configured and arranged to be associated with a coupling capacitance that changes in response to a capacitance-altering touch at the touch surface, the drive electrodes being driven by a drive signal; a sense circuit coupled to the receive electrodes, and configured to generate response signals for the plurality of electrodes; each of the response signals has an amplitude responsive to the coupling capacitance at the touch surface and including a differentiated signal representation of the drive signal transmitted through the electrodes and giving rise to the response signal, the response signal having transient portions characterizing positive-going transitions of the drive signal towards an upper signal level of the drive signal and negative-going transitions of the drive signal towards a lower signal level of the drive signal; and an amplification circuit (284 & 290) configured and arranged to provide time-varying parameters for characterizing the transient portions, the amplification circuit (284 & 290) including a variable-gain amplifier configured and arranged for processing the differentiated signal representation of the response signals to provide variable gain thereto, in response to the time-varying parameters, the gain being adjusted for the transient portions relative to gain for portions of the response signals between the transient portions, and therein suppressing harmonics in the response signals for providing a noise filtered output that characterizes the associated coupling capacitance for determining positions of touches on the touch surface. a touch surface circuit including a touch surface and a plurality of drive electrodes and receive electrodes, each of the plurality of electrodes being configured and arranged to be associated with a coupling capacitance that changes in response to a capacitance-altering touch at the touch surface, the drive electrodes being driven by a drive signal; a sense circuit coupled to the receive electrodes, and configured to generate response signals for the plurality of electrodes; each of the response signals has an amplitude responsive to the coupling capacitance at the touch surface and including a differentiated signal representation of the drive signal transmitted through the electrodes and giving rise to the response signal, the response signal having transient portions characterizing positive-going transitions of the drive signal towards an upper signal level of the drive signal and negative-going transitions of the drive signal towards a lower signal level of the drive signal; and an amplification circuit (284 & 290) configured and arranged to provide time-varying parameters for characterizing the transient portions, the amplification circuit (284 & 290) including a variable-gain amplifier configured and arranged for processing the differentiated signal representation of the response signals to provide variable gain thereto, in response to the time-varying parameters, the gain being adjusted for the transient portions relative to gain for portions of the response signals between the transient portions, and therein suppressing harmonics in the response signals for providing a noise filtered output that characterizes the associated coupling capacitance for determining positions of touches on the touch surface.