Touch sensing device and display apparatus including the same

A touch sensing device comprising:

• a first buffer connected to a first touch electrode through a first touch sensing line, the first buffer including a first output circuit including a first pull-up circuit having a cascode configuration and a first pull-down circuit having a cascode configuration;
• a second buffer connected to a second touch electrode through a second touch sensing line, the second buffer including a second output circuit including a second pull-up circuit having a cascode configuration and a second pull-down circuit having a cascode configuration;
• a first current mirror unit connected to the first buffer to generate a first mirror current by performing a mirroring operation on a first current flowing in the first pull-up circuit and to generate a third mirror current by performing a mirroring operation on a second current flowing in the first pull-down circuit;
• a second current mirror unit connected to the second buffer to generate a second mirror current by performing a mirroring operation on a first current flowing in the second pull-up circuit and to generate a fourth mirror current by performing a mirroring operation on a second current flowing in the second pull-down circuit;
• a filter circuit configured to generate a first filter signal and a second filter signal by removing common noise included in a first output signal generated from the first mirror current and the third mirror current and a second output signal generated from the second mirror current and the fourth mirror current;
• and
• an integrator connected to the filter circuit to integrate and output a difference between the first filter signal and the second filter signal.

A display apparatus comprising:

• a touch screen panel including a plurality of touch electrodes and a plurality of touch sensing lines connected to the plurality of touch electrodes to each transmit a reception signal corresponding to a capacitance generated in a corresponding touch electrode;
• and
• a touch sensing device connected to the plurality of touch sensing lines to sense whether a touch is applied thereto, wherein the touch sensing device comprises:
• a plurality of buffers respectively connected to the plurality of touch sensing lines to each buffer a difference between a reference signal and a reception signal received from a corresponding touch electrode through a corresponding touch sensing line and generate first and second currents corresponding to a buffered signal;
• a plurality of current mirror unit respectively connected to the plurality of buffers to generate a first output signal from a first mirror current generated through mirroring of the first current and a third mirror current generated through mirroring of the second current and generate a second output signal from a second mirror current generated through mirroring of the first current and a fourth mirror current generated through mirroring of the second current;
• a plurality of filter circuits configured to perform a differential operation on a first output signal output from an nth (where n is an integer of 2 or more) current mirror unit of the plurality of current mirror units and a second output signal output from an (n−1)th current mirror unit of the plurality of current mirror units to generate the first filter signal, where common noise is removed from the first output signal and the second filter signal and where the common noise is removed from the second output signal;
• and
• a plurality of integrators respectively connected to the plurality of buffers to integrate and output a difference between the first filter signal and the second filter signal respectively output from the plurality of filter circuits,
• wherein the nth current mirror unit corresponds to a nth touch sensing line and the (n−1)th current mirror unit corresponds to a (n−1)th touch sensing line, and
• wherein an output of the nth current mirror unit and an output of the (n−1)th current mirror unit are connected to a same filter circuit among the plurality of filter circuits and the same filter circuit removes noise commonly input through the nth touch sensing line and the (n−1)th touch sensing line.