Multi-Channel Capacitance Sensing Measurement Circuit

A capacitance measurement circuit (12) for determining complex electric currents in a multi-channel capacitive sensing device (10) comprises a first sensing circuit (18) for selectively connecting one of a plurality of sense electrodes to a common sense node (14) and for connecting a corresponding guard electrode of the sense electrode to a common guard node (16), and at least a second sensing circuit (26). A measurement signal voltage source (42) provides an alternating measurement voltage to the common guard node (16) in a remotely controllable manner. A diagnostic signal voltage source (46) provides an alternating diagnostic voltage to the common guard node (16) in a remotely controllable manner. A current measurement circuit (52) is connected with a signal input port (56) to the common sense node (14) and with a reference input port (58) to the output port (44) of the measurement signal voltage source (42).