Touch sensing apparatus

A touch sensing apparatus comprising:

• a high pass filter configured to decide a second cut-off frequency by varying the resistance of at least one of a first resistor which transfers a touch sensing signal outputted from a sensing electrode to a first amplifier and is implemented with a variable resistor and a second resistor which forms a first feedback loop for the first amplifier and is implemented with the variable resistor, and output a first output signal obtained by filtering a frequency component equal to or lower than the second cut-off frequency in the touch sensing signal, and
• a low pass filter comprising a sampling switch which switches transfer of the first output signal, a third resistor which transfers the first output signal having passed through the sampling switch to a second amplifier and is implemented with the variable resistor, and a feedback capacitor which forms a second feedback loop for the second amplifier and is implemented with a variable capacitor, and configured to sample the first output signal during a sampling period, decide a third cut-off frequency by varying at least one of the resistance of the third resistor and the capacitance of the feedback capacitor, and output a second output signal obtained by filtering a frequency component equal to or higher than the third cut-off frequency in the first output signal,
• wherein the sampling period is maintained for a second time from a time point delayed by a first time based on a transition time point of a driving signal applied to a driving electrode and is periodically changed with reference to the second output signal, and
• wherein the time point is later than a start time of the first output signal outputted from the high pass filter.