SWITCHED-CAPACITOR TRACKING APPARATUS OF TOUCH PANEL AND OPERATING METHOD THEREOF
First Claim
1. A switched-capacitor tracking apparatus of a touch panel configured to track a capacitance variation of a panel capacitor, comprising:
- a variable capacitor;
an auxiliary capacitor;
a first switch having a first terminal coupled to a first reference voltage and a second terminal coupled to the panel capacitor;
a second switch having a first terminal coupled to the panel capacitor;
a third switch having a first terminal coupled to a second reference voltage and a second terminal coupled to the variable capacitor;
a fourth switch having a first terminal coupled to the variable capacitor and a second terminal coupled to the second terminal of the second switch, wherein the first switch and the third switch are turned on and the second switch and the fourth switch are turned off in a charge period of a first clock signal, and the first switch and the third switch are turned off and the second switch and the fourth switch are turned on in a detection period of the first clock signal;
a fifth switch having a first terminal coupled to the second reference voltage and a second terminal coupled to the auxiliary capacitor;
a sixth switch having a first terminal coupled to the auxiliary capacitor and a second terminal coupled to the second terminal of the second switch; and
a control circuit coupled to the second terminal of the second switch, the control circuit configured to set a capacitance of the variable capacitor according to a first capacitor step value, to compare a third reference voltage and a voltage at the second terminal of the second switch, to control the fifth switch and the sixth switch according to a comparison result, and to accumulate a plurality of the comparison results in a statistics period, wherein if all the comparison results in the statistics period are a first logic value, then the control circuit increases the first capacitor step value, and if all the comparison results in the statistics period are a second logic value, then the control circuit decreases the first capacitor step value.
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Accused Products
Abstract
A switched-capacitor tracking apparatus including a variable capacitor, an auxiliary capacitor, and a plurality of switches, and an operating method thereof are provided. In a charge period, a first reference voltage charges a panel capacitor, and a second reference voltage charges the variable capacitor. In a detection period, a control circuit detects a parallel connected voltage of the panel capacitor and the variable capacitor. The control circuit compares a third reference voltage and the parallel connected voltage. According to a comparison result, the control circuit dynamically determines whether to parallel connect the auxiliary capacitor to the variable capacitor. If all the comparison results accumulated in a statistics period are a first logic value, then the control circuit increases a capacitance of the variable capacitor. Moreover, if all the comparison results are a second logic value in the statistics period, then the control circuit decreases the capacitance of the variable capacitor.
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Citations
22 Claims
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1. A switched-capacitor tracking apparatus of a touch panel configured to track a capacitance variation of a panel capacitor, comprising:
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a variable capacitor; an auxiliary capacitor; a first switch having a first terminal coupled to a first reference voltage and a second terminal coupled to the panel capacitor; a second switch having a first terminal coupled to the panel capacitor; a third switch having a first terminal coupled to a second reference voltage and a second terminal coupled to the variable capacitor; a fourth switch having a first terminal coupled to the variable capacitor and a second terminal coupled to the second terminal of the second switch, wherein the first switch and the third switch are turned on and the second switch and the fourth switch are turned off in a charge period of a first clock signal, and the first switch and the third switch are turned off and the second switch and the fourth switch are turned on in a detection period of the first clock signal; a fifth switch having a first terminal coupled to the second reference voltage and a second terminal coupled to the auxiliary capacitor; a sixth switch having a first terminal coupled to the auxiliary capacitor and a second terminal coupled to the second terminal of the second switch; and a control circuit coupled to the second terminal of the second switch, the control circuit configured to set a capacitance of the variable capacitor according to a first capacitor step value, to compare a third reference voltage and a voltage at the second terminal of the second switch, to control the fifth switch and the sixth switch according to a comparison result, and to accumulate a plurality of the comparison results in a statistics period, wherein if all the comparison results in the statistics period are a first logic value, then the control circuit increases the first capacitor step value, and if all the comparison results in the statistics period are a second logic value, then the control circuit decreases the first capacitor step value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification