Input sensing device and display device including the same
A display device includes driving electrodes and sensing electrodes; analog front-end circuits; a selector connected to the analog front-end circuits to select an output of the analog front-end circuits; an A/D converter generating a sensed value based on output signals of the selector; and a signal processor. Each of the analog front-end circuits includes a charge amplifier differentially amplifying first and second sensing signals provided to first and second input terminals, and outputting first and second differential signals to first and second output terminals; a filter filtering the first and second differential signals to output first and second filtered signals; a demodulator outputting an in-phase signal (I-signal) and a quadrature signal (Q-signal) of the first and second filtered signals; and a complex band-pass filter that filters the I-signal and the Q-signal.
1. An input sensing device comprising:
a sensor array comprising a plurality of electrodes; and
an analog circuit to process a first sensing signal and a second sensing signal provided from the sensor array to output analog signals,
wherein the analog circuit comprises:
an amplifier to differentially amplify the first sensing signal and the second sensing signal to output a first differential signal and a second differential signal; and
a demodulator to output in-phase signals corresponding to the first and second differential signals and to output quadrature signals corresponding to the first and second differential signals,
wherein the output analog signals are based on the in-phase signals and the quadrature signals.
2. The input sensing device of claim 1 , further comprising an analog-to-digital converter to generate sensor data in a digital format based on the output analog signals.
3. The input sensing device of claim 2 , further comprising a signal processor to sense a user input on the sensor array based on the sensor data.
4. The input sensing device of claim 1 , wherein the analog circuit comprises a complex band-pass filter to filter the in-phase signals and the quadrature signals.
5. The input sensing device of claim 4 , wherein the analog circuit further comprises a synthesizer connected to the complex band-pass filter, and configured to synthesize the filtered in-phase signals and the filtered quadrature signals to generate a first real signal and a second real signal, and
wherein the first and second real signals are provided as the output analog signals.
6. The input sensing device of claim 5 , wherein the synthesizer comprises:
a phase shifter to shift a phase of the filtered quadrature signals; and
an adder to add one of the shifted quadrature signals to one of the filtered in-phase signals to generate the first real signal, and to add a remaining one of the shifted quadrature signals to a remaining one of the filtered in-phase signals to generate the second real signal.
7. The input sensing device of claim 4 , further comprising an analog-to-digital converter to generate sensor data in a digital format based on the filtered in-phase signals and the filtered quadrature signals, the filtered in-phase signals and the filtered quadrature signals being provided as the output analog signals.
8. The input sensing device of claim 7 , wherein the sensor data includes a first sensed value corresponding to the filtered in-phase signals and a second sensed value corresponding to the filtered quadrature signals.
9. The input sensing device of claim 8 , further comprising a signal processor to sense an external input based on the sensor data,
wherein the signal processor comprises a synthesizer to digitally calculate the first sensed value and the second sensed value to generate a final sensed value.
10. The input sensing device of claim 7 , wherein the analog-to-digital converter comprises a complex delta-sigma analog-to-digital converter.
11. The input sensing device of claim 4 , wherein each of the filtered in-phase signals and the filtered quadrature signals includes only a positive frequency component, or only a negative frequency component.
12. The input sensing device of claim 4 , wherein the analog circuit further comprises a filter to filter the first differential signal and the second differential signal to generate a first filtered signal and a second filtered signal.
13. The input sensing device of claim 12 , wherein the demodulator comprises:
an oscillation circuit to output first local oscillation signals and second local oscillation signals orthogonal to the first local oscillation signals;
a first mixer circuit to apply the first local oscillation signals to the first and second filtered signals to output the in-phase signals; and
a second mixer circuit to apply the second local oscillation signals to the first and second filtered signals to output the quadrature signals.
14. The input sensing device of claim 1 , wherein the amplifier comprises a charge amplifier.
15. The input sensing device of claim 1 , wherein the analog circuit comprises an analog front-end circuit.
16. A display device comprising:
a display panel including pixels;
a sensor array comprising a plurality of electrodes; and
an analog circuit to process a first sensing signal and a second sensing signal provided from the sensor array to output analog signals,
wherein the analog circuit comprises:
an amplifier to differentially amplify the first sensing signal and the second sensing signal to output a first differential signal and a second differential signal; and
a demodulator to output in-phase signals corresponding to the first and second differential signals and to output quadrature signals corresponding to the first and second differential signals,
wherein the output analog signals are based on the in-phase signals and the quadrature signals.
17. The display device of claim 16 , further comprising an analog-to-digital converter to generate sensor data in a digital format based on the output analog signals.
18. The display device of claim 17 , further comprising a signal processor to sense an external input on the sensor array based on the sensor data.
19. The display device of claim 16 , wherein the amplifier comprises a charge amplifier.
20. The display device of claim 16 , wherein the analog circuit comprises an analog front-end circuit.