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Capacitance measurement circuit and capacitance measurement method

A capacitance measurement, capacitance technology, applied in the direction of measuring electrical variables, measuring resistance/reactance/impedance, measuring devices, etc.

Inactive Publication Date: 2010-06-16
RAYDIUM SEMICON
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The invention relates to a capacitance measurement circuit and a capacitance measurement method thereof, which not only greatly improve the disadvantages of the old circuit being easily affected by switching noise, but also provide clock signals for other circuits without additional purchase of oscillators.

Method used

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  • Capacitance measurement circuit and capacitance measurement method
  • Capacitance measurement circuit and capacitance measurement method
  • Capacitance measurement circuit and capacitance measurement method

Examples

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no. 1 example

[0058] Please also refer to Figure 4 , 5 , 6, 7 and 8, Figure 4 and 5 Partial detailed circuit diagrams of the capacitance measuring circuit are shown respectively, Figure 6 shows a detailed circuit diagram of the capacitance variable circuit, Figure 7 shows the signal timing diagram of the first embodiment, Figure 8 A schematic diagram of an analog-to-digital converter is shown. The aforementioned capacitance measurement circuit 30 can selectively operate during the capacitance value setting period or the capacitance value measurement period. The capacitance measurement circuit 30 can preferably adjust the equivalent capacitance value of the adjustable variable capacitance Cx in advance during the capacitance value setting period, so that the capacitance measurement circuit 30 can more accurately measure the capacitance C to be measured during the capacitance value measurement period. Y .

[0059] The capacitance-to-time unit 310 includes an adjustable capacitance...

no. 2 example

[0084] Please also refer to Figure 9 and Figure 10 , Figure 9 shows a partial detailed circuit diagram of the capacitance measuring circuit of the second embodiment, Figure 10 A signal timing chart of the second embodiment is shown. The difference between the second embodiment and the first embodiment lies in that the design of the current source 414 of the second embodiment is different from that of the current source 314 of the first embodiment. In addition to the operational amplifier OP1, the n-channel metal-oxide-semiconductor (NMOS) transistor LN1 as a switch, the p-channel metal-oxide-semiconductor (PMOS) transistors LP1 and LP2 as a switch, and the resistor Rb, the current source 414 also includes a switch The p-channel metal oxide semiconductor (PMOS) transistor LP2A. The current source 414 makes the current flow through the capacitor under test C Y It is K times different from the current of the adjustable variable capacitor Cx. In this way, the adjustable ...

no. 3 example

[0086] Please also refer to Figure 11 , which shows a partial detailed circuit diagram of the capacitance measuring circuit of the third embodiment. The difference between the third embodiment and the first embodiment lies in that the design of the current source 514 of the third embodiment is different from that of the current source 314 of the first embodiment. Current source 514 divides operational amplifier OP1, n-channel metal-oxide-semiconductor (NMOS) transistor LN1 as a switch, p-channel metal-oxide-semiconductor (PMOS) transistor LP1 as a switch, p-channel metal-oxide-semiconductor (PMOS) transistor as a switch In addition to the transistor LP2 and the resistor Rb, a transistor array 5142 is also included. The transistor array 5142 is controlled by the current setting signal ISEL[N:0] to provide K times the current I2.

[0087] Please refer to Figure 12 , which shows a detailed circuit diagram of the transistor array. The transistor array 5142 includes transisto...

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PUM

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Abstract

The invention provides a capacitance measurement circuit and a capacitance measurement method. The capacitance measurement circuit is used to measure a capacitor to be tested. The capacitance measurement circuit comprises a capacitance-to-time unit, a continuous time integrator and an analog-to-digital converter, wherein the capacitance-to-time unit generates a first clock signal and a second clock signal which are opposite in phase according to a first charging time of the capacitor to be tested and a second charging time of a controllable capacitor; the continuous time integrator receives the first clock signal and output an integrated signal according to the first clock signal; and when the number of the clock pulses of the second clock signal is equal to a default value, the analog-to-digital converter outputs a digital signal which is related to the difference value of the capacitor to be tested and the controllable capacitor according to the integrated signal.

Description

technical field [0001] The invention relates to a capacitance measuring circuit and a capacitance measuring method, in particular to a capacitance measuring circuit using a continuous time integrator and a capacitance measuring method thereof. Background technique [0002] Please refer to FIG. 1 and FIG. 2 at the same time, which show a circuit diagram of a conventional capacitance measurement circuit. The conventional capacitance measuring circuits 10 and 20 are used to measure the capacitance variation of the capacitance Cz to be measured and convert it into a digital signal for output. The capacitance Cz to be measured is a capacitor whose capacitance value changes after being triggered. For example, the X-direction or Y-direction sensing line (sensing line) of the capacitive touch screen will change capacitance when touched by a conductor. Capacitor array 150 is a capacitor array whose size can be selected by switches to provide equivalent capacitance C R , and the ca...

Claims

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Application Information

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IPC IPC(8): G01R27/26
Inventor 光宇
Owner RAYDIUM SEMICON
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