Capacitance measurement circuit and method
A technology for measuring circuits and measuring methods, which is applied in the direction of measuring electrical variables, measuring resistance/reactance/impedance, measuring devices, etc., and can solve problems such as affecting the measurement results of capacitance values.
Inactive Publication Date: 2011-05-04
RAYDIUM SEMICON
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Problems solved by technology
[0005] However, with the existing capacitance measurement circuit, if there is noise in the input voltage source, the noise will be coupled into the capacitance measurement circuit, thereby affecting the capacitance measurement result
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[0022] In the capacitance measurement circuit and the capacitance measurement method of the embodiments of the present invention, the capacitance measurement is performed in a differential manner, so the anti-noise capability can be improved.
[0023] Please refer to figure 1 , which shows a schematic circuit diagram of the capacitance measuring circuit according to the first embodiment of the present invention. like figure 1 As shown, the capacitance measurement circuit 100 according to the first embodiment of the present invention includes: a reference capacitor CR, a capacitor to be measured (sensor capacitor) CS, a coupling capacitor CC, an operational amplifier 110, and a continuous approximation register (Successive Approximation Register, SAR) 120 , a digital-to-analog converter (DAC) 130, a switch S1, a switch S2, a switch SC1, and a switch SC2. In addition, CP1 and CP2 represent the parasitic capacitance of the capacitance measuring circuit 100 . The register 140 i...
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The invention discloses a capacitance measurement circuit which comprises an operational amplifier, a reference capacitor, a capacitor to be measured, an approach unit, a conversion unit and a coupling capacitor, wherein the operational amplifier is provided with a first input end, a second input end and an output end; the reference capacitor is provided with a first end and a second end, wherein the first end is coupled with the first input end of the operational amplifier and the second end is selectively coupled with a first reference voltage or a second reference voltage; the capacitor to be measured is provided with a first end and a second end, wherein the first end is coupled with the second input end of the operational amplifier and the second end is selectively coupled with the first reference voltage or the second reference voltage; the approach unit is provided with an input end and an output end, wherein the input end is coupled with the output end of the operational amplifier; the conversion unit is provided with an input end and an output end, wherein the input end is coupled with the output end of the approach unit; and the coupling capacitor is provided with a first end and a second end, wherein the first end is coupled with the first input end or the second input end of the operational amplifier and the second end is coupled with the output end of the conversion unit. The invention also provides a capacitance measurement method for measuring the capacitance of the capacitor to be measured.
Description
technical field [0001] The invention relates to a capacitance value measuring circuit and a capacitance value measuring method, and in particular to a capacitance value measuring circuit and a capacitance value measuring method for measuring in a differential manner. Background technique [0002] Traditionally, most of the user control interfaces are realized by mechanical switches. Since the user needs to directly touch the traditional mechanical switch, the traditional mechanical switch can be operated in response to the user's control command, and the traditional mechanical device is easy to be damaged during the user's operation. Currently, tactile switches have been developed. The touch switch is, for example, a capacitive switch or the like. [0003] In order to improve the convenience of use, currently developed touch panels or display touch panels (having both display and touch functions) can accept user's input, click and other operations. The touch panel or disp...
Claims
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IPC IPC(8): G01R27/26G06F3/044H03K17/96
Inventor 周世宗饶永年光宇
Owner RAYDIUM SEMICON