WO2018137166A1 - 差分电路 - Google Patents

差分电路 Download PDF

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Publication number
WO2018137166A1
WO2018137166A1 PCT/CN2017/072526 CN2017072526W WO2018137166A1 WO 2018137166 A1 WO2018137166 A1 WO 2018137166A1 CN 2017072526 W CN2017072526 W CN 2017072526W WO 2018137166 A1 WO2018137166 A1 WO 2018137166A1
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WO
WIPO (PCT)
Prior art keywords
electrode
coupled
electrodes
differential circuit
amplifier
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PCT/CN2017/072526
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English (en)
French (fr)
Inventor
洪自立
杨富强
文亚南
Original Assignee
深圳市汇顶科技股份有限公司
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Application filed by 深圳市汇顶科技股份有限公司 filed Critical 深圳市汇顶科技股份有限公司
Priority to CN201780000066.2A priority Critical patent/CN107078705B/zh
Priority to PCT/CN2017/072526 priority patent/WO2018137166A1/zh
Priority to EP17893702.5A priority patent/EP3413177B1/en
Publication of WO2018137166A1 publication Critical patent/WO2018137166A1/zh
Priority to US16/116,902 priority patent/US10642430B2/en

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/045—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45479—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection
    • H03F3/45928—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection using IC blocks as the active amplifying circuit

Definitions

  • the present application relates to a differential circuit, and more particularly to a differential circuit that can effectively eliminate common mode noise.
  • the operational interfaces of various electronic products have gradually become more humanized in recent years.
  • the user can directly operate on the screen with a finger or a stylus, input a message/text/pattern, and save the trouble of using an input device such as a keyboard or a button.
  • the touch screen usually consists of a sensing panel and a display disposed behind the sensing panel.
  • the electronic device judges the meaning of the touch according to the position touched by the user on the sensing panel and the picture presented by the display at the time, and executes the corresponding operation result.
  • the receiving electrodes on the touch screen are affected by common mode noise, which has approximately the same effect on all receiving electrodes in the touch screen.
  • SNR signal-to-noise ratio
  • a primary object of some embodiments of the present invention is to provide a differential circuit that can effectively eliminate common mode noise to improve the shortcomings of the prior art.
  • the present application provides a differential circuit including a plurality of electrodes having at least one intermediate electrode, wherein an intermediate electrode of at least one of the intermediate electrodes is directly adjacent to a first electrode of the plurality of electrodes and a second electrode; a plurality of amplifiers coupled to the plurality of electrodes; and at least one buffer coupled between the intermediate electrode and at least one of the plurality of amplifiers.
  • the intermediate electrode is coupled to a first amplifier and a second amplifier of the plurality of amplifiers.
  • the first amplifier includes a first input end and a second input end
  • the second amplifier includes a third input end and a fourth input end
  • the first input end is coupled to the first
  • An electrode is coupled to the second electrode
  • the intermediate electrode is coupled to the second input end and the third input end.
  • a buffer of the at least one buffer is coupled between the intermediate electrode and the second input of the first amplifier.
  • a buffer of the at least one buffer is coupled between the intermediate electrode and the third input of the second amplifier.
  • the differential circuit further includes a plurality of transconductance units coupled between the plurality of inputs of the plurality of amplifiers and the plurality of electrodes.
  • a transconductance unit of the plurality of transconductance units is a resistor.
  • the differential circuit further includes a plurality of impedance units coupled between the plurality of inputs of the plurality of amplifiers and the plurality of outputs.
  • an impedance unit of the plurality of impedance units includes a resistor or a capacitor.
  • an amplifier of the plurality of amplifiers is a fully differential operational amplifier.
  • Figure 1 is a schematic diagram of a differential circuit.
  • FIG. 2 is a schematic diagram of a differential circuit according to an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a differential circuit according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a differential circuit according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram of an amplifier and a plurality of impedance units according to an embodiment of the present application.
  • FIG. 1 is a schematic diagram of a differential circuit 10.
  • the differential circuit 10 can be applied to a touch screen including electrodes RX_0 to RX_N and amplifiers Amp_1 to Amp_N.
  • the amplifiers Amp_1-Amp_N can be a Full Differential Operation Amplifier, and the electrodes RX_0-RX_N can be connected to the touch-sensing receiving electrodes on the touch screen, and the touch-determining module in the touch screen (not shown in FIG. 1)
  • the magnitude of the capacitance corresponding to the electrodes RX_0 to RX_N can be determined based on the voltage or current of the electrodes RX_0 to RX_N to further determine the coordinate position at which the touch occurs.
  • the electrodes RX_0 to RX_N are subject to a common mode noise.
  • Common-ModeNoise affects the accuracy of determining the touch position, wherein the common mode noise can be noise from a display screen (not shown in Figure 1).
  • the amplifiers Amp_1 to Amp_N (coupled to the electrodes RX_0 to RX_N) can be used to obtain the differential signals Vo_1 to Vo_N between the electrodes RX_0 to RX_N.
  • a negative input terminal (labeled with a "-" sign) of the amplifier Amp_n is coupled to the electrode RX_n-1
  • a positive input terminal (labeled with a "+” sign) of the amplifier Amp_n is coupled to the electrode RX_n
  • Vo_n A differential signal between the representative electrode RX_n-1 and the electrode RX_n, where n is a positive integer from 1 to N.
  • the electrodes RX_0 and RX_N are boundary electrodes (of the electrodes RX_0 to RX_N), and the electrodes RX_1 to RX_N-1 are intermediate electrodes (between the electrodes RX_0 and RX_N); the electrodes RX_0 and RX_N are boundary electrodes.
  • the finger electrodes RX_0 and RX_N are directly adjacent to a single electrode, and the electrodes RX_1 to RX_N-1 are intermediate electrodes. It means that any of the electrodes RX_1 to RX_N-1 is directly adjacent to the two electrodes.
  • one of the electrodes RX_0 to RX_N directly adjacent to the one electrode RX_b means that the electrode RX_a is adjacent to the electrode RX_b and there is no electrode between the electrode RX_a and the electrode RX_b, and the differential circuit 10 is taken as an example, the electrode RX_0 and the electrode RX_1 is adjacent, and there is no electrode between the electrode RX_0 and the electrode RX_1, that is, the electrode RX_0 is directly adjacent to the electrode RX_1; the electrode RX_N is adjacent to the electrode RX_N-1, and the electrode RX_N is only present between the electrode RX_N-1 and the electrode RX_N-1 Any electrode, that is, the electrode RX_N is directly adjacent to the electrode RX_N-1.
  • the electrode RX_0 is directly adjacent to the electrode RX_1, and the electrode RX_N is directly adjacent to the electrode RX_N-1. Therefore, the electrodes RX_0 and RX_N are boundary electrodes.
  • any one of the electrodes RX_1 to RX_N-1 is directly adjacent to the electrode RX_m-1 and the electrode RX_m+1 at the same time. (m is a positive integer of 1 to N-1), that is, the electrode RX_m is directly adjacent to the electrode RX_m-1 and the electrode RX_m+1, and therefore, the electrodes RX_1 to RX_N-1 are intermediate electrodes.
  • each of the intermediate electrodes RX_1 to RX_N-1 is coupled to the two amplifiers at the same time to generate a current shunting effect, which results in a decrease in the accuracy of the interpretation of the touch position.
  • the intermediate electrode RX_m (m is a positive integer of 1 to N-1)
  • the intermediate electrode RX_m is simultaneously coupled to the positive input terminal of the amplifier Amp_m and the negative input terminal of the amplifier Amp_m+1, in this case,
  • the current flowing through the intermediate electrode RX_m is shunted into a current I+ and a current I-, wherein the current I+ flows from the intermediate electrode RX_m to the positive input terminal of the amplifier Amp_m, and the current I- flows from the intermediate electrode RX_m to the negative of the amplifier Amp_m+1.
  • the current shunting effect changes the operating point of the amplifier Amp_m (or amplifier Amp_m+1), so that the voltage at the positive input of the amplifier Amp_m (or the negative input of the amplifier Amp_m+1) is at the intermediate electrode.
  • the voltage of RX_m is different, so that the differential signal Vo_m cannot accurately represent the voltage difference between the electrode RX_m-1 and the electrode RX_m (or the differential signal Vo_m+1 cannot accurately represent the voltage difference between the electrode RX_m and the electrode RX_m+1). ), and reduce the accuracy of determining the touch position.
  • the differential circuit of the present application utilizes a buffer to block/block the current splitting of the intermediate electrode to one of the amplifiers, thereby solving the problem of determining the accuracy of the touch position by shunting the current flowing through the intermediate electrode to the input end of the two amplifiers.
  • the problem of falling can add a buffer having a high input impedance between the intermediate electrode RX_m and the amplifier Amp_m (or the amplifier Amp_m+1) to block/block the current of the intermediate electrode RX_m from being shunted to the amplifier Amp_m (or the amplifier Amp_m). +1), which improves the accuracy of determining the touch position.
  • FIG. 2 is a schematic diagram of a differential circuit 20 according to an embodiment of the present application.
  • the difference circuit 20 is similar to the differential circuit 10, so the same components follow the same symbols.
  • the difference circuit 20 includes buffers BF_1 to BF_N-1, and the buffers BF_1 to BF_N-1 correspond to the intermediate electrodes RX_1 to RX_N-1, and are coupled to the intermediate electrodes RX_1 to RX_N-1 and the amplifier.
  • the buffer BF_m corresponds to the intermediate electrode RX_m and is coupled between the intermediate electrode RX_m and the positive input terminal of the amplifier Amp_m.
  • the buffer BF_1 is coupled between the intermediate electrode RX_1 and the positive input terminal of the amplifier Amp_1 corresponding to the intermediate electrode RX_1, and the buffer BF_2 is coupled to the positive input of the intermediate electrode RX_2 and the amplifier Amp_2 corresponding to the intermediate electrode RX_2.
  • the buffer BF_N-1 is coupled between the intermediate electrode RX_N-1 and the positive input terminal of the amplifier Amp_N-1 corresponding to the intermediate electrode RX_N-1.
  • the buffer BF_m coupled between the intermediate electrode RX_m and the positive input terminal of the amplifier Amp_m has a high input impedance, and can be used to block/block the current I+ shunted by the intermediate electrode RX_m to the positive input terminal of the amplifier Amp_m.
  • the positive input terminal of the amplifier Amp_m is equal to the voltage of the intermediate electrode RX_m, and the differential signal Vo_m can accurately represent the voltage difference between the electrode RX_m-1 and the electrode RX_m, thereby improving the accuracy of determining the touch position.
  • the differential circuit 20 further includes a plurality of transconductance units R, and the plurality of transconductance units R are coupled between the plurality of input terminals of the amplifiers Amp_1 ⁇ Amp_N and the electrodes RX_0 ⁇ RX_N.
  • the cross The guiding unit R can be a resistor.
  • the differential circuit 20 further includes a plurality of impedance units Z.
  • the impedance unit Z can be coupled between the negative input terminal of the amplifier Amp_n and a positive output terminal (labeled with a "+" sign), or can be coupled to the amplifier Amp_n. Between the input and a negative output (labeled with a "-"), in one embodiment, the impedance Unit Z can be formed by a resistor.
  • FIG. 3 is a schematic diagram of a differential circuit 30 according to an embodiment of the present application.
  • the differential circuit 30 is similar to the differential circuit 20, so the same components follow the same symbols.
  • the buffers BF_1 to BF_N-1 correspond to the intermediate electrodes RX_1 to RX_N-1, and are coupled between the intermediate electrodes RX_1 to RX_N-1 and the amplifiers Amp_2 to Amp_N.
  • the buffer BF_m corresponds to the intermediate electrode RX_m and is coupled between the intermediate electrode RX_m and the negative input terminal of the amplifier Amp_m+1 to block/block the current shunted by the intermediate electrode RX_m to the negative input of the amplifier Amp_m+1. I-, also falls within the scope of this application.
  • each of the buffers BF_1 BFBF_N-1 is coupled between the intermediate electrode RX_m and the positive input terminal of the amplifier Amp_m
  • the differential circuit 30 the buffers BF_1 BF BF_N-
  • Each of the buffers BF_m is coupled between the intermediate electrode RX_m and the negative input terminal of the amplifier Amp_m+1.
  • the differential circuit of the present application is not limited thereto.
  • FIG. 4 is a schematic diagram of a differential circuit 40 according to an embodiment of the present application.
  • the differential circuit 40 is similar to the differential circuits 20 and 30, so the same components follow the same symbols.
  • a portion of the buffers BF_1 to BF_N-1 are coupled between the intermediate electrode RX_m1 and the positive input terminal of the amplifier Amp_m1, and the buffers BF_1 to BF_N.
  • Another portion of the buffer BF_m2 is coupled between the intermediate electrode RX_m2 and the negative input terminal of the amplifier Amp_m2+1 (m1 and m2 are positive integers of 1 to N-1) as long as the buffers BF_1 to BF_N-1 are included.
  • One end of each buffer BF_m is coupled to the intermediate electrode RX_m, and the other end is coupled to the positive input terminal of the amplifier Amp_m.
  • one of the negative inputs of the amplifier Amp_m+1 which satisfies the requirements of the present application, is within the scope of the present application.
  • the impedance unit Z is not limited to being composed only of a resistor, and the impedance unit Z may also include a capacitor.
  • FIG. 5 is a schematic diagram of an amplifier Amp_n and a plurality of impedance units Z5 according to an embodiment of the present application.
  • the impedance unit Z5 may include a resistor and a capacitor, and the impedance unit Z5 may be coupled between the negative input terminal and the positive output terminal of the amplifier Amp_n, or coupled to the positive input terminal and the negative output terminal of the amplifier Amp_n. Between the ends, it is also within the scope of this application.
  • the present application utilizes a buffer having a high input impedance to prevent current flowing through the intermediate electrode from shunting to another amplifier such that the differential signal can accurately represent the voltage difference between two directly adjacent electrodes.
  • the present application can improve the accuracy of determining the touch position.

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Abstract

一种差分电路，包括多个电极(RX_0～RX_N)，具有至少一中间电极(RX_1～RX_N－1)，其中至少一中间电极(RX_1～RX_N－1)中一中间电极直接相邻于所述多个电极(RX_0～RX_N)中一第一电极及一第二电极；多个放大器(Amp_1～Amp_N)，耦接于所述多个电极(RX_0～RX_N)；以及至少一缓冲器(BF_1～BF_N－1)，耦接于所述中间电极与所述多个放大器(Amp_1～Amp_N)中至少一放大器之间。

Description

差分电路 技术领域
本申请涉及一种差分电路，尤其涉及一种可有效消除共模噪声的差分电路。
背景技术
随着科技日益进步，近年来各种电子产品的操作接口逐渐人性化。举例而言，透过触控面板，使用者可直接以手指或触控笔在屏幕上操作、输入讯息/文字/图样，省去使用键盘或按键等输入设备的麻烦。实际上，触控屏通常由一感应面板及设置于感应面板后方的显示器组成。电子装置根据用户在感应面板上所触碰的位置，以及当时显示器所呈现的画面，来判断该次触碰的意涵，并执行相对应的操作结果。
详细来说，触控屏上的接收电极会受到共模噪声的影响，其中共模噪声对触控屏中所有接收电极造成大致相同的影响。在信噪比(Signal-to-Noise Ratio，SNR)很小的情况下，触控信号会淹没在共模噪声当中，而无法确的判断触控发生的位置。因此，如何有效地消除触控屏接收电极的共模噪声，就成为业界所努力的目标之一。
发明内容
因此，本发明部分实施例主要目的即在于提供一种可有效消除共模噪声的差分电路，以改善习知技术的缺点。
为了解决上述技术问题，本申请提供了一种差分电路，包括多个电极，具有至少一中间电极，其中至少一中间电极中一中间电极直接相邻于所述多个电极中一第一电极及一第二电极；多个放大器，耦接于所述多个电极；以及至少一缓冲器，耦接于所述中间电极与所述多个放大器中至少一放大器之间。
例如，所述中间电极耦接于所述多个放大器中一第一放大器以及一第二放大器。
例如，所述第一放大器包含一第一输入端及一第二输入端，所述第二放大器包含一第三输入端及一第四输入端，所述第一输入端耦接于所述第一电极，所述第四输入端耦接于所述第二电极，所述中间电极耦接于所述第二输入端以及所述第三输入端。
例如，所述至少一缓冲器中一缓冲器耦接于所述中间电极与所述第一放大器的所述第二输入端之间。
例如，所述至少一缓冲器中一缓冲器耦接于所述中间电极与所述第二放大器的所述第三输入端之间。
例如，所述差分电路另包含多个跨导单元，耦接于所述多个放大器的多个输入端与所述多个电极之间。
例如，所述多个跨导单元的一跨导单元为一电阻。
例如，所述差分电路另包含多个阻抗单元，耦接于所述多个放大器的多个输入端与多个输出端之间。
例如，所述多个阻抗单元的一阻抗单元包含一电阻或一电容。
例如，所述多个放大器的一放大器为一全差分运算放大器。
附图说明
一个或多个实施例通过与之对应的附图中的图片进行示例性说明，这些示例性说明并不构成对实施例的限定，附图中具有相同参考数字标号的元件表示为类似的元件，除非有特别申明，附图中的图不构成比例限制。
图1为一差分电路的示意图。
图2为本申请实施例一差分电路的示意图。
图3为本申请实施例一差分电路的示意图。
图4为本申请实施例一差分电路的示意图。
图5为本申请实施例一放大器与多个阻抗单元的示意图。
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限定本申请。
请参考图1，图1为一差分电路10的示意图。差分电路10可应用于一触控屏，其包含电极RX_0～RX_N以及放大器Amp_1～Amp_N。放大器Amp_1～Amp_N可为全差分运算放大器(Full Differential Operation Amplifier)，电极RX_0～RX_N可连接到触控屏上的触摸感应接收电极，触控屏中的触控判断模块(未绘示于图1)可根据电极RX_0～RX_N的电压或电流判断对应于电极RX_0～RX_N的电容大小，以进一步判断触控发生的坐标位置。一般来说，电极RX_0～RX_N皆会受到一共模噪声 (Common-ModeNoise)的影响，而降低判断触控位置的精准度，其中，共模噪声可为来自一显示屏(未绘示于图1)的噪声。为了消除共模噪声对电极RX_0～RX_N的电容判读的影响，(耦接于电极RX_0～RX_N的)放大器Amp_1～Amp_N可用来取得电极RX_0～RX_N之间的差分信号Vo_1～Vo_N。详细来说，放大器Amp_n的一负输入端(标示有「－」号)耦接于电极RX_n－1，放大器Amp_n的一正输入端(标示有「+」号)耦接于电极RX_n，而Vo_n代表电极RX_n－1与电极RX_n之间的差分信号，其中n为1至N的正整数。
于差分电路10中，电极RX_0、RX_N为(电极RX_0～RX_N的)边界电极，而电极RX_1～RX_N－1为(电极RX_0与电极RX_N之间的)中间电极；电极RX_0、RX_N为边界电极是指电极RX_0及电极RX_N仅与单一电极直接相邻，而电极RX_1～RX_N－1为中间电极是指电极RX_1～RX_N－1中任一电极皆与二电极直接相邻。其中，电极RX_0～RX_N中一电极RX_a与一电极RX_b直接相邻是指电极RX_a与电极RX_b相邻且电极RX_a与电极RX_b之间不存在任何电极，以差分电路10为例，电极RX_0与电极RX_1相邻，而电极RX_0与电极RX_1之间不存在任何电极，即电极RX_0与电极RX_1直接相邻；电极RX_N与电极RX_N－1相邻，而电极RX_N仅与电极RX_N－1之间不存在任何电极，即电极RX_N与电极RX_N－1直接相邻。需注意的是，电极RX_0仅与电极RX_1直接相邻，而电极RX_N与电极RX_N－1直接相邻，因此，电极RX_0、RX_N为边界电极。另一方面，电极RX_1～RX_N－1中的任一电极RX_m同时与电极RX_m－1以及电极RX_m+1直接相邻 (m为1至N－1的正整数)，即电极RX_m直接相邻于电极RX_m－1以及电极RX_m+1，因此，电极RX_1～RX_N－1为中间电极。
然而，中间电极RX_1～RX_N－1中每一中间电极因同时耦接于二个放大器，而产生电流分流效应，而导致判读触控位置的精准度下降。详细来说，以中间电极RX_m例(m为1至N－1的正整数)，中间电极RX_m同时耦接于放大器Amp_m的正输入端以及放大器Amp_m+1的负输入端，在此情形下，流经中间电极RX_m的电流会分流成一电流I+以及一电流I－，其中电流I+自中间电极RX_m流至于放大器Amp_m的正输入端，而电流I－自中间电极RX_m流至于放大器Amp_m+1的负输入端。然而，电流分流效应会改变放大器Amp_m(或放大器Amp_m+1)的操作点(Operating Point)，而使得于放大器Amp_m的正输入端(或放大器Amp_m+1的负输入端)的电压与于中间电极RX_m的电压不同，导致差分信号Vo_m无法精确地代表电极RX_m－1与电极RX_m之间的电压差(或导致差分信号Vo_m+1亦无法精确地代表电极RX_m与电极RX_m+1之间的电压差)，而降低判断触控位置的精准度。
因此，本申请的差分电路利用缓冲器来阻挡/阻却中间电极的电流分流至其中之一放大器，来解决因流经中间电极的电流分流至二放大器的输入端，而导致判断触控位置精准度下降的问题。换句话说，本申请可于中间电极RX_m与放大器Amp_m(或放大器Amp_m+1)之间加入具有高输入阻抗的一缓冲器，以阻挡/阻却中间电极RX_m的电流分流至放大器Amp_m(或放大器Amp_m+1)，进而提升判断触控位置的精准度。
举例来说，请参考图2，图2为本申请实施例一差分电路20的示意 图。差分电路20与差分电路10类似，故相同组件沿用相同符号。与差分电路10不同的是，差分电路20包含缓冲器BF_1～BF_N－1，缓冲器BF_1～BF_N－1对应于中间电极RX_1～RX_N－1，而耦接于中间电极RX_1～RX_N－1与放大器Amp_1～Amp_N－1之间，换句话说，缓冲器BF_m对应于中间电极RX_m，而耦接于中间电极RX_m与放大器Amp_m的正输入端之间。举例来说，缓冲器BF_1对应于中间电极RX_1而耦接于中间电极RX_1与放大器Amp_1的正输入端之间，缓冲器BF_2对应于中间电极RX_2而耦接于中间电极RX_2与放大器Amp_2的正输入端之间，以此类推，缓冲器BF_N－1对应于中间电极RX_N－1而耦接于中间电极RX_N－1与放大器Amp_N－1的正输入端之间。
在此情形下，耦接于中间电极RX_m与放大器Amp_m的正输入端之间的缓冲器BF_m因具有高输入阻抗，而可用来阻挡/阻却由中间电极RX_m分流至放大器Amp_m正输入端的电流I+，使得放大器Amp_m的正输入端等于中间电极RX_m的电压，而差分信号Vo_m可精确地代表电极RX_m－1与电极RX_m之间的电压差，进而提升判断触控位置的精准度。
另外，差分电路20另包含多个跨导(Transconductance)单元R，多个跨导单元R耦接于放大器Amp_1～Amp_N的多个输入端与电极RX_0～RX_N之间，于一实施例中，跨导单元R可为一电阻。差分电路20另包含多个阻抗单元Z，阻抗单元Z可耦接于放大器Amp_n的负输入端与一正输出端(标示有「+」号)之间，或是可耦接于放大器Amp_n的正输入端与一负输出端(标示有「－」号)之间，于一实施例中，阻抗 单元Z可由一电阻所构成。
需注意的是，前述实施例系用以说明本申请之概念，本领域具通常知识者当可据以做不同之修饰，而不限于此。举例来说，请参考图3，图3为本申请实施例一差分电路30的示意图，差分电路30与差分电路20类似，故相同组件沿用相同符号。与差分电路20不同的是，于差分电路30中，缓冲器BF_1～BF_N－1对应于中间电极RX_1～RX_N－1，而耦接于中间电极RX_1～RX_N－1与放大器Amp_2～Amp_N之间，换句话说，缓冲器BF_m对应于中间电极RX_m，而耦接于中间电极RX_m与放大器Amp_m+1的负输入端之间，以阻挡/阻却由中间电极RX_m分流至放大器Amp_m+1负输入端的电流I－，亦属于本申请的范畴。
另外，于差分电路20中，缓冲器BF_1～BF_N－1中每一缓冲器BF_m耦接于中间电极RX_m与放大器Amp_m的正输入端之间，而于差分电路30中，缓冲器BF_1～BF_N－1中每一缓冲器BF_m耦接于中间电极RX_m与放大器Amp_m+1的负输入端之间，然而，本申请的差分电路不限于此。举例来说，请参考图4，图4为本申请实施例一差分电路40的示意图，差分电路40与差分电路20、30类似，故相同组件沿用相同符号。与差分电路20、30不同的是，于差分电路40中，缓冲器BF_1～BF_N－1中部分缓冲器BF_m1耦接于中间电极RX_m1与放大器Amp_m1的正输入端之间，而缓冲器BF_1～BF_N－1中另一部分缓冲器BF_m2耦接于中间电极RX_m2与放大器Amp_m2+1的负输入端之间(m1、m2皆为1至N－1的正整数)，只要缓冲器BF_1～BF_N－1中每一缓冲器BF_m的一端耦接于中间电极RX_m，另一端耦接于放大器Amp_m的正输入端 或放大器Amp_m+1的负输入端其中之一，皆满足本申请的要求而属于本申请的范畴。
另外，阻抗单元Z不限于仅由电阻所构成，阻抗单元Z亦可包含一电容。举例来说，请参考图5，图5为本申请实施例放大器Amp_n与多个阻抗单元Z5的示意图。于图5所示，阻抗单元Z5可包含一电阻及一电容，阻抗单元Z5可耦接于放大器Amp_n的负输入端与正输出端之间，或耦接于放大器Amp_n的正输入端与负输出端之间，亦属于本申请的范畴。
综上所述，本申请利用具有高输入阻抗的缓冲器，来阻止流经中间电极的电流分流至另一放大器，使得差分信号可精确地代表两直接相邻电极之间的电压差。相较于现有技术，本申请可提升判断触控位置的精准度。
以上所述仅为本申请的部分实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种差分电路，所述差分电路包括：
    多个电极，具有至少一中间电极，所述中间电极直接相邻于所述多个电极中一第一电极以及一第二电极；
    多个放大器，耦接于所述多个电极；以及
    至少一缓冲器，耦接于所述中间电极与所述多个放大器中至少一放大器之间。
  2. 如权利要求1所述的差分电路，其中，所述中间电极耦接于所述多个放大器中一第一放大器以及一第二放大器。
  3. 如权利要求2所述的差分电路，其中，所述第一放大器包括一第一输入端及一第二输入端，所述第二放大器包括一第三输入端及一第四输入端，所述第一输入端耦接于所述第一电极，所述第四输入端耦接于所述第二电极，所述中间电极耦接于所述第二输入端以及所述第三输入端。
  4. 如权利要求3所述的差分电路，其中，所述缓冲器耦接于所述中间电极与所述第一放大器的所述第二输入端之间。
  5. 如权利要求3所述的差分电路，其中，所述缓冲器耦接于所述中间电极与所述第二放大器的所述第三输入端之间。
  6. 如权利要求1所述的差分电路，其中，进一步包括：
    多个跨导单元，耦接于所述多个放大器的多个输入端与所述多个电极之间。
  7. 如权利要求6所述的差分电路，其中，所述跨导单元包括一电阻。
  8. 如权利要求1所述的差分电路，其中，进一步包括：
    多个阻抗单元，耦接于所述多个放大器的多个输入端与多个输出端之间。
  9. 如权利要求8所述的差分电路，其中，所述阻抗单元包括一电阻或一电容。
  10. 如权利要求1所述的差分电路，其中，所述放大器包括一全差分运算放大器。
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