CN105099426A - Capacitive touch control sensing circuit - Google Patents

Capacitive touch control sensing circuit Download PDF

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Publication number
CN105099426A
CN105099426A CN201410186530.XA CN201410186530A CN105099426A CN 105099426 A CN105099426 A CN 105099426A CN 201410186530 A CN201410186530 A CN 201410186530A CN 105099426 A CN105099426 A CN 105099426A
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CN
China
Prior art keywords
output
input
switch
touch control
control sensing
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CN201410186530.XA
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Chinese (zh)
Inventor
叶奇典
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盛群半导体股份有限公司
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Priority to CN201410186530.XA priority Critical patent/CN105099426A/en
Publication of CN105099426A publication Critical patent/CN105099426A/en

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Abstract

The invention discloses a capacitive touch control sensing circuit, which comprises a touch-type sensor, an operational amplifier, an integral capacitor, a first switch, and a second switch, wherein the touch-type sensor is provided with a sensor capacitor, and one end of the sensor capacitor is grounded; one input end of the operational amplifier receives a reference voltage; two ends of the integral capacitor are respectively connected with the other input end and the output end of the operational amplifier; the first switch is connected between the other end of the sensor capacitor and the other input end of the operational amplifier; the second switch is connected between one end of the sensor capacitor and an input voltage end; and the first switch and the second switch have opposite trigger pulse phases. Thus, the integral capacitor can be reduced to a picofarad level via the capacitive touch control sensing circuit, and the integral capacitor can be built in the circuit.

Description

Capacitance type touch control sensing circuit

Technical field

The present invention has about a kind of touch control sensing circuit, particularly relates to a kind of capacitance type touch control sensing circuit.

Background technology

US Patent No. 6466036 discloses a kind of charging transmission capacitance measurement circuit, with reference to its specification and its Fig. 1, before starting to sense, first switch S 3 is closed, makes integrating capacitor S3 discharge (Reset); Then carry out closing switch S1 and open switch S 2 and open switch S 1 and closing switch S2 alternating movement, will progressively be accumulated by the voltage of integrating capacitor CS, with reference to its specification and its accompanying drawing.After charging transmission N time, the voltage of integrating capacitor CS is: V cS(N)=Δ V cS(1)+Δ V cS(2)+Δ V cS(3)+... + Δ V cS(N)

Wherein, Δ V cS(n)=K (V r-V cS(n-1)), K=C x/ (C s+ C x)

The representative value of contact pickup electric capacity CX is 20pF, Vr=5V, and we are respectively 30pF and 10nF to illustrate the impact of integration capacitor value with integrating capacitor CS:

As integrating capacitor CS=10nF, VCS (N)=4V, N=806

As integrating capacitor CS=50pF, VCS (N)=4V, N=5

Clearly, as CS=50pF, N=5, the number of times of charging transmission is too little, is therefore not enough to the touch differentiating finger; As CS=10nF, N=806, the number of times of charging transmission is enough to the contact differentiating finger.But during CS=10nF, cannot in be built within integrated circuit, therefore integrating capacitor CS needs outer being hung on outside integrated circuit.

Summary of the invention

The invention discloses a kind of capacitance type touch control sensing circuit, for solve integrating capacitor in existing capacitance type touch control sensing circuit cannot in be built in problem within circuit.

A kind of capacitance type touch control sensing circuit of the present invention, comprising: touch sensor, has sensor capacitance, one end ground connection of this sensor capacitance; Operational amplifier, an input of this operational amplifier receives a reference voltage; Integrating capacitor, its two ends connect another input and the output of this operational amplifier respectively; First switch, is connected between the other end of this sensor capacitance and this another input of this operational amplifier; And second switch, between this one end being connected to this sensor capacitance and an Input voltage terminal; Wherein, this first switch is contrary with the trigger impulse phase place of this second switch.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, also comprise: digital to analog converter, it receives digital controlled signal, and provides this reference voltage to this operational amplifier.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, the positive input terminal of this operational amplifier receives reference voltage, and negative input end connects this integrating capacitor and this first switch.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, also comprise: the 3rd switch, in parallel with this integrating capacitor, between this another input being connected to this operational amplifier and this output.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, this reference voltage is less than the voltage of this Input voltage terminal.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, also comprise: random number generator, it receives a clock signal, and exports a periodicity means of chaotic signals according to this clock signal; Non-overlapping circuit, its periodicity means of chaotic signals exported according to this random number generator, produces the two anti-phase irregular triggering signals of periodicity, and provides this anti-phase triggering signal respectively to this first switch and this second switch.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, this random number generator comprises: multiple shift register, and the plurality of shift register concatenation connects, this clock signal of the clock input of the plurality of shift register; At least one XOR gate, two inputs of this XOR gate connect the output of two shift registers respectively, and input connects the input of the shift register before the input of this two shift register.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, this non-overlapping circuit comprises: first exports tandem, comprise the inverter of one first XOR gate and multiple series connection, the input of a wherein inverter of the inverter of the plurality of series connection of output of this first XOR gate, the output of wherein this inverter of the inverter of the plurality of series connection connects this first switch as this first output exporting tandem; Second exports tandem, comprise the inverter of one second XOR gate and multiple series connection, the input of a wherein inverter of the inverter of the plurality of series connection of output of this second XOR gate, the output of wherein this inverter of the inverter of the plurality of series connection connects this second switch as this second output exporting tandem; Wherein, one input of this first XOR gate connects the output of this random number generator, another input connects this output of this second output tandem, be connected by an inverter between one input of this second XOR gate and the output of this random number generator, another input connects this output of this first output tandem.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, this random number generator is the random number generator of 4,8 or 16.

According to an embodiment of capacitance type touch control sensing circuit of the present invention, wherein, this clock signal is multiple Frequency Hopping Signal.

To sum up, integrating capacitor can be reduced to pf level by the present invention, make integrating capacitor can in be built in circuit.And there is the noise protection ability that integrating capacitor is built-in and excellent.In addition, coordinate the noise protection circuit of capacitance type touch control sensing circuit of the present invention, integrate the skill of LFSR and frequency hopping, make this circuit add immunity for the interference of integrating capacitor CS test and power supply noise etc.

Accompanying drawing explanation

Figure 1 shows that the schematic diagram of an embodiment of capacitance type touch control sensing circuit of the present invention;

Figure 2 shows that the schematic diagram of another embodiment of capacitance type touch control sensing circuit of the present invention;

Figure 3 shows that the schematic diagram of 4 bit linear feedback shift registers;

Figure 4 shows that the signal composition schematic diagram of linear feedback shift register;

The schematic diagram of 8 bit linear feedback shift registers shown in Fig. 5;

The schematic diagram of 16 bit linear feedback shift registers shown in Fig. 6

Figure 7 shows that the connection diagram of linear feedback shift register and non-overlapping circuit;

Figure 8 shows that the signal timing diagram of linear feedback shift register and non-overlapping circuit;

Figure 9 shows that the connection diagram of another embodiment of linear feedback shift register and non-overlapping circuit;

Figure 10 shows that the time diagram of Fig. 9;

Figure 11 shows that the circuit diagram with Frequency Hopping Signal input that circuit shown in Fig. 7 is corresponding;

Figure 12 shows that the circuit diagram with Frequency Hopping Signal input that circuit shown in Fig. 9 is corresponding;

Figure 13 shows that the output voltage oscillogram over time of operational amplifier in specific works process.

Embodiment

Figure 1 shows that the schematic diagram of an embodiment of capacitance type touch control sensing circuit of the present invention, as shown in Figure 1, the capacitance type touch control sensing circuit of the present embodiment comprises: touch sensor has sensor capacitance Cx, operational amplifier 1, digital to analog converter (DAC) 3, integrating capacitor Cs, the first switch S D, second switch SC and the 3rd switch S R.

With reference to figure 1, the 3rd switch S R is in parallel with integrating capacitor Cs, and the negative input end of difference concatenation operation amplifier 1 and output.The positive input of operational amplifier 1 connects DAC3, and negative input connects the first switch S D.DAC3 provides reference voltage VREF according to external signal to operational amplifier 1.One end ground connection of sensor capacitance Cx, the other end connects the first switch S D and second switch SC respectively.Second switch SC receives input voltage AVDR, and input voltage AVDR is the voltage of system power supply after low pressure difference linear voltage regulator (LDO) regulates.

With further reference to Fig. 1, in reality, the output reference voltage VREF of DAC3 can be adjusted, reference voltage VREF is less than but close input voltage AVDR, and then make the electric charge being transferred to integrating capacitor Cs not too large.The changing value △ Cx of the sensor capacitance Cx after finger touching sensor is desired measuring value, therefore can not need to strengthen integrating capacitor Cs to store D. C. value, the electric charge corresponding to changing value △ Cx only needing integrating capacitor Cs to store.Because operational amplifier 1 is negative feedback, the positive and negative terminal of operational amplifier 1 is input as imaginary short, make when the first switch S D closes, the voltage of sensor capacitance Cx can be fixed on reference voltage VREF, therefore the quantity of electric charge having Cx*VREF can be retained on sensor capacitance Cx, only has the Charger transfer of Cx* (AVDR-VREF) to integrating capacitor Cs.This voltage drop by operational amplifier 1 output (AVDR-VREF) * Cx/Cs, therefore the voltage of operational amplifier 1 output is VREF-(AVDR-VREF) * Cx/Cs.As from the foregoing, owing to only transferring the electric charge of fraction to integrating capacitor Cs, therefore the capacitance of integrating capacitor Cs does not just need too large.

Figure 2 shows that the schematic diagram of another embodiment of capacitance type touch control sensing circuit of the present invention, as shown in Figure 2, because touch control sensing circuit is changed with fixing frequency, therefore easy this frequency or its resonance frequency disturbed.In view of frequency spectrum, on fixing its frequency spectrum of frequency representation, concentration of energy is near this frequency, therefore needs the situation by spectrum energy is concentrated to break up.Originally clock signal has the fixing cycle, frequently must change cycle fixing situation, its cycle can arbitrarily be changed in order to perform exhibition.Therefore, the capacitance type touch control sensing main circuit of the present embodiment will add random number generator 4 and non-overlapping circuit 5.Random number generator 4 connects non-overlapping circuit 5, and non-overlapping circuit 5 controls the opening and closing of the first switch S D and second switch SC respectively.Random number generator 4 is broken up for the clock signal of the regularity by input, makes its cycle irregular.The cycle irregular signal of non-overlapping circuit 5 then for exporting according to random number generator 4, produce the irregular triggering signal of periodicity that two-way is anti-phase, a road is for triggering the first switch S D, and another road is for triggering second switch SC.

Figure 3 shows that the schematic diagram of 4 bit linear feedback shift registers, as shown in Figure 3, the random number generator of the present embodiment is a linear feedback shift register (LinearFeedbackShiftregister is called for short LFSR).Be described for the LFSR of the 4-bit in Fig. 3, the shift register X1-X4 of LFSR is connected in series, one input of XOR gate XOR1 connects the Q end of shift register X4, and another input connects the Q end of shift register X3, and output connects the D end of shift register X1.The CK end of regular clock signal difference input shift register X1-X4.

Figure 4 shows that the signal composition schematic diagram of linear feedback shift register, as shown in Figure 3 and 4, the output signal of the Q end of X1-X4 difference corresponding displaced register X1-X4 in Fig. 4, wherein 0 representative exports as low level signal, 1 representative exports as high level signal, the digitized representation in the multiple circle in left side by right side with the shift register X1-X4 of a line binary digit represented by metric value.As seen from the figure, if the Q of 4 shift registers (X1, X2, X3, X4) holds initial value to correspond to (1000), final outputting ten binary digits will be 8 → 4 → 2 → 9 → 12 → 6 → 11 → 5 → 10 → 13 → 14 → 15 → 7 → 3 → 1 → 8.The Q end of shift register X4 exports, and should be have regular clock signal originally, after LFSR, its output be 000100110101111.In the present embodiment, although the signal of above-mentioned LFSR can repeat after 15 circulations, significantly improve the monotonicity of its frequency.Through the LFSR equivalence frequency reducing of this 4-bit, in the above-mentioned time, the clock signal of input should have the conversion of 15 0 → 1 originally, and the clock signal of input is by the conversion through 40 → 1 after LFSR.Can expect that the LFSR of 8-bit can repeat after 255 circulations, therefore the figure place of LFSR the more, and the circulation of repetition can increase.Should notice that the initial value that LFSR inputs should be 0, with the state avoiding LFSR to be in 0000.

The schematic diagram of 8 bit linear feedback shift registers shown in Fig. 5, as shown in Figure 5, the LFSR of 8bit comprises: 8 shift register X1-X8 and XOR gate XOR1-XOR3.One input of XOR gate XOR1 connects the Q end of shift register X4, and another input connects the output of XOR gate XOR2.One input of XOR gate XOR2 connects the Q end of shift register X5, and another input connects the output of XOR gate XOR3.XOR gate XOR3 mono-input connects the Q end of shift register X6, and another input connects the Q end of shift register X8.

The schematic diagram of 16 bit linear feedback shift registers shown in Fig. 6, as shown in Figure 6, the LFSR of 16bit comprises: 16 shift register X1-X16 and XOR gate XOR1-XOR3.One input of XOR gate XOR1 connects the Q end of shift register X11, and another input connects the output of XOR gate XOR2.One input of XOR gate XOR2 connects the Q end of shift register X13, and another input connects the output of XOR gate XOR3.XOR gate XOR3 mono-input connects the Q end of shift register X14, and another input connects the Q end of shift register X16.

Figure 7 shows that the connection diagram of linear feedback shift register and non-overlapping circuit, as shown in Figure 7, the present embodiment is for the LFSR of 4bit, non-overlapping circuit connects the output of LFSR, non-overlapping circuit comprises the first output tandem 11 and the second output exporting tandem 12, second output tandem and LFSR is connected with not gate 13.First output tandem 11 comprises inverter NOT1, NOT2 and NOT3 of NAND gate NAND1 and series connection.The output of NAND gate NAND1 connects the input of inverter NOT1, and the output of inverter NOT3 exports the output of tandem 11 as first, send triggering signal to switch S C.Second output tandem 12 comprises inverter NOT4, NOT5 and NOT6 of NAND gate NAND2 and series connection.The output of NAND gate NAND2 connects the input of inverter NOT4, and the output of inverter NOT6 exports the output of tandem 12 as second, send triggering signal to switch S D.

Figure 8 shows that the signal timing diagram of linear feedback shift register and non-overlapping circuit, as shown in Figure 8, the clock signal of the waveforms stands input that clock is corresponding, the waveform that LFSR is corresponding is the signal that LFSR exports, the waveform that SC is corresponding is the SC triggering signal that the first output tandem 11 exports, and the waveform that SD is corresponding is the SD triggering signal that the second output tandem 12 exports.As shown in Figure 8, after the clock signal input LFSR of periodic law, the signal exported is cycle erratic signal.The waveform of SC triggering signal and the waveform of SD triggering signal anti-phase.

Figure 9 shows that the connection diagram of another embodiment of linear feedback shift register and non-overlapping circuit, as shown in Figure 9, the present embodiment is provided with one and door AND1 between LFSR and non-overlapping circuit, the Q being connected shift register X4 with an input of door AND1 holds, the other end receives the clock signal of input, and be connected non-overlapping circuit with the output of door AND1 two export tandem.

Figure 10 shows that the time diagram of Fig. 9, contrast can find out with reference to figure 9 and Figure 10, add with door AND1 after, the second triggering signal length exporting the waveform of tandem 11 and the second output tandem 12 is half clock cycle.

Figure 11 shows that the circuit diagram with Frequency Hopping Signal input that circuit shown in Fig. 7 is corresponding, Figure 12 shows that the circuit diagram with Frequency Hopping Signal input that circuit shown in Fig. 9 is corresponding, for the output spectrum of 4-bitLFSR, compare with original clock signal, because LFSR has the more time to be in the state of 1 or 0, although the exhibition of the existing certain degree of the frequency spectrum being therefore contemplated to LFSR is frequently, more energy is had to be in low-frequency range, therefore will be more weak at the noise immunity of low-frequency range.Due to the situation that the low and high level change frequency of LFSR is more, the phenomenon that low frequency energy is assembled is slighter.Clock signal clk1, clk2, clk3 and clk4 of input different frequency can be converted at set intervals, to solve the above problems.

In conjunction with previous embodiment, the operation principle of capacitance type touch control sensing circuit is described:

Before finger contact touch sensor, comprising:

S1: close the 3rd switch S R to reset integrating capacitor Cs, now the output end voltage of operational amplifier 1 is VREF, opens the 3rd switch S R afterwards;

S2: close second switch SC, charged to sensor capacitance Cx by input voltage AVDR, the quantity of electric charge of sensor capacitance Cx is Cx*AVDR, opens second switch SC afterwards;

S3: then close the first switch S D, the electric charge of sensor capacitance Cx is discharged to integrating capacitor Cs, integrating capacitor Cs is transferred to by there being the quantity of electric charge of Cx* (AVDR-VREF), the output of operational amplifier 1, by decline Cx* (AVDR-VREF)/Cs, opens the first switch S D afterwards;

Repeat above-mentioned S2 and S3, N time, then the output voltage of operational amplifier 1 is by decline N*Cx* (AVDR-VREF)/Cs, and the voltage that last operational amplifier 1 exports is VREF-N*Cx* (AVDR-VREF)/Cs;

S4: the value of output reference voltage VREF of adjustment DAC3, makes the output valve of operational amplifier 1 be greater than 0 and level off to 0.

After finger contact touch sensor, sensor electrical capacitance increases to Cx+ △ Cx, and the operation now carried out, comprising:

S5: close second switch SC, charged to sensor capacitance Cx by input voltage AVDR, the quantity of electric charge of sensor capacitance Cx is (Cx+ △ Cx) * AVDR, opens second switch SC afterwards;

S6: then close the first switch S D, the electric charge of sensor capacitance Cx is discharged to integrating capacitor Cs, integrating capacitor Cs is transferred to by there being the quantity of electric charge of (Cx+ △ Cx) * (AVDR-VREF), the output of operational amplifier 1 will decline (Cx+ △ Cx) * (AVDR-VREF)/Cs, open the first switch S D afterwards;

Repeat above-mentioned S5 and S6, N time, then the output of operational amplifier 1 is by decline N* (Cx+ △ Cx) * (AVDR-VREF)/Cs, and the voltage that last operational amplifier 1 exports is VREF-N* (Cx+ △ Cx) * (AVDR-VREF)/Cs;

Above-mentioned N arrives the number of times needed for electric capacity Cs for Charger transfer, and namely because the value of electric capacity Cx becomes large, the electric charge being passed to electric capacity Cs becomes many, and it is less that the output voltage of operational amplifier 1 can become.

Figure 13 shows that the output voltage oscillogram over time of operational amplifier in specific works process, at this setting Cx=20pF, △ Cx=2pF, AVDR=3.3V, visible in the process of step S1, the output voltage of operational amplifier 1 keeps VREF, and in the process repeating step S2 and S3, the output voltage approximately linear change of operational amplifier 1, the final drop-out voltage final for operational amplifier 1 is AVDR/6.So, the touch of finger can be found out.

Following table 1-5 illustrates the relation of size at the built-in integrating capacitor Cs of the present invention and op-amp output voltage value with the analogue data of multiple reality.

Represent in following table, adjust the situation of change after various different reference VREF and integrating capacitor Cs: wherein, the capacitance of electric capacity Cx after being touched can become large, therefore have new electric charge to need to be passed to electric capacity Cs, after Δ N refers to finger touch, the number of times that N reduces, Δ V refers to that operational amplifier 1 exports the voltage declined.

Table 1:

Table 2:

Table 3:

Table 4:

Table 5:

Cs is that pF grade can be used for touch-control sensing really as seen from the above table, as shown in table 5 especially, and under the condition of Cs=10pF, when VREF is quite near AVDR, increased by the absolute value of Δ N, the absolute value of Δ N is larger, is more not easy misjudged.

To sum up, integrating capacitor can be reduced to pf level by the present invention, make integrating capacitor can in be built in circuit.A kind of capacitance type touch control sensing circuit of the present invention, has the noise protection ability that integrating capacitor is built-in and excellent.In addition, coordinate the noise protection circuit of capacitance type touch control sensing circuit of the present invention, integrate the skill of LFSR and frequency hopping, make this circuit add immunity for the interference of integrating capacitor CS test and power supply noise etc.

Although exemplary embodiment describe the present invention with reference to several, should be appreciated that term used illustrates and exemplary and nonrestrictive term.Spirit of the present invention or essence is not departed from because the present invention can specifically implement in a variety of forms, so be to be understood that, above-described embodiment is not limited to any aforesaid details, and should explain widely in the spirit and scope that claims limit, therefore fall into whole change in claim or its equivalent scope and remodeling and all should be claims and contained.

Claims (10)

1. a capacitance type touch control sensing circuit, is characterized in that, comprising:
Touch sensor, has sensor capacitance, one end ground connection of this sensor capacitance;
Operational amplifier, an input of this operational amplifier receives a reference voltage;
Integrating capacitor, its two ends connect another input and the output of this operational amplifier respectively;
First switch, is connected between the other end of this sensor capacitance and this another input of this operational amplifier; And
Second switch, between this one end being connected to this sensor capacitance and an Input voltage terminal;
Wherein, this first switch is contrary with the trigger impulse phase place of this second switch.
2. capacitance type touch control sensing circuit as claimed in claim 1, it is characterized in that, also comprise: digital to analog converter, it receives digital controlled signal, and provides this reference voltage to this operational amplifier.
3. capacitance type touch control sensing circuit as claimed in claim 1, it is characterized in that, the positive input terminal of this operational amplifier receives this reference voltage, and negative input end connects this integrating capacitor and this first switch.
4. capacitance type touch control sensing circuit as claimed in claim 1, is characterized in that, also comprise: the 3rd switch, in parallel with this integrating capacitor, between this another input being connected to this operational amplifier and this output.
5. capacitance type touch control sensing circuit as claimed in claim 1, it is characterized in that, this reference voltage is less than the voltage of this Input voltage terminal.
6. capacitance type touch control sensing circuit as claimed in claim 1, is characterized in that, also comprise:
Random number generator, it receives a clock signal, and exports a periodicity means of chaotic signals according to this clock signal;
Non-overlapping circuit, its periodicity means of chaotic signals exported according to this random number generator, produces the two anti-phase irregular triggering signals of periodicity, and provides this anti-phase triggering signal respectively to this first switch and this second switch.
7. capacitance type touch control sensing circuit as claimed in claim 6, it is characterized in that, this random number generator comprises:
Multiple shift register, the plurality of shift register concatenation connects, this clock signal of the clock input of the plurality of shift register;
At least one XOR gate, two inputs of this XOR gate connect the output of two shift registers respectively, and input connects the input of the shift register before the input of this two shift register.
8. capacitance type touch control sensing circuit as claimed in claim 7, it is characterized in that, this non-overlapping circuit comprises:
First exports tandem, comprise the inverter of one first XOR gate and multiple series connection, the output of this first XOR gate connects the input of a wherein inverter of the inverter of the plurality of series connection, and the output of wherein this inverter of the inverter of the plurality of series connection connects this first switch as this first output exporting tandem;
Second exports tandem, comprise the inverter of one second XOR gate and multiple series connection, the output of this second XOR gate connects the input of a wherein inverter of the inverter of the plurality of series connection, and the output of wherein this inverter of the inverter of the plurality of series connection connects this second switch as this second output exporting tandem;
Wherein, one input of this first XOR gate connects the output of this random number generator, another input connects this output of this second output tandem, be connected by an inverter between one input of this second XOR gate and the output of this random number generator, another input connects this output of this first output tandem.
9. capacitance type touch control sensing circuit as claimed in claim 1, it is characterized in that, this random number generator is the random number generator of 4,8 or 16.
10. capacitance type touch control sensing circuit as claimed in claim 1, it is characterized in that, this clock signal is multiple Frequency Hopping Signal.
CN201410186530.XA 2014-05-05 2014-05-05 Capacitive touch control sensing circuit CN105099426A (en)

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WO2017114514A1 (en) * 2015-12-31 2017-07-06 深圳市汇顶科技股份有限公司 Integrating circuit and capacitance sensing circuit
CN107436699A (en) * 2016-05-26 2017-12-05 奇景光电股份有限公司 Touch control sensing circuit and embedded display panel

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CN103078611A (en) * 2012-12-28 2013-05-01 香港中国模拟技术有限公司 Clock generator and switched capacitor circuit comprising same
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US6883717B1 (en) * 2004-04-14 2005-04-26 International Business Machines Corporation Secure credit card employing pseudo-random bit sequences for authentication
CN101539826A (en) * 2008-03-21 2009-09-23 统宝光电股份有限公司 Image display system
US7863966B1 (en) * 2009-09-17 2011-01-04 Himax Technologies Limited Readout circuit for touch panel
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Publication number Priority date Publication date Assignee Title
WO2017114514A1 (en) * 2015-12-31 2017-07-06 深圳市汇顶科技股份有限公司 Integrating circuit and capacitance sensing circuit
CN107436699A (en) * 2016-05-26 2017-12-05 奇景光电股份有限公司 Touch control sensing circuit and embedded display panel

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Application publication date: 20151125