CN100566164C - A kind of high precision capacitance touching induction control circuit framework - Google Patents
A kind of high precision capacitance touching induction control circuit framework Download PDFInfo
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- CN100566164C CN100566164C CNB2007100379766A CN200710037976A CN100566164C CN 100566164 C CN100566164 C CN 100566164C CN B2007100379766 A CNB2007100379766 A CN B2007100379766A CN 200710037976 A CN200710037976 A CN 200710037976A CN 100566164 C CN100566164 C CN 100566164C
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Abstract
The invention discloses a kind of high precision capacitance touching induction control circuit framework, adopt constant current source charging principle touch sensitive capacitance variations, realized the high accuracy that inductance capacitance changes; It comprises voltage buffer, current setting resistance, current mirror, initial comparator, finishes comparator and time-to-digit converter, and it also comprises induction pin equivalent capacity and low reference pin equivalent capacity; Described reference voltage produces reference current by voltage buffer and current setting resistance, and described reference current produces charging current respectively to described induction pin equivalent capacity and the charging of low reference pin equivalent capacity by current mirror; The low reference pin equivalent capacity excites described initial comparator, and time-to-digit converter picks up counting, and excites described end comparator by induction pin equivalent capacity, and time-to-digit converter finishes timing and will convert transfer of data the time interval to give processor processing.
Description
Technical field
The present invention relates to a kind of circuit framework, particularly a kind of high precision capacitance touching induction control circuit framework that is used for capacitive touch sensors.
Background technology
Capacitive touch sensors is applicable among any product of present employing conventional mechanical switch, particularly small and exquisite portable product, menu control button as trendy mobile phone or media player, utilize the reliability height and have cost-benefit capacitive touch screen, can change the style of these advanced menu control switchs like a cork, give a kind of brand-new operation feeling of people.And the capacitive touch screen that is applied in the white domestic appliances can avoid water and greasy dirt to the damage of button and household electrical appliances itself, promotes the hommization and the fail safe of household electrical appliances.Another benefit that capacitive touch sensors replaces traditional mechanical switch is to make with assembly technology simpler.Traditional mechanical switch needs manual each switch to be inserted among the special hole above the plastic casing, and a single capacitive touch screen plate that comprises all these switches can settle at one go, is placed on below this plastic casing.Contain the sensor board installing hole of a locating notch and installation and the position correction that some glue just are enough to finish sensor board.Along with the development of mixed signal technology, capacitive touch sensors is just becoming a kind of practicality, the appreciation type replacement scheme of mechanical switch in the various electronic products.
Shown in Fig. 1 (a), simple plane-parallel capacitor has two pole plates, therebetween across one deck dielectric, so go up between bottom crown an intrinsic inductance capacitance C is just arranged
SENSOR(inductance capacitance represents to touch pole plate intrinsic direct-to-ground capacitance before touch here).Shown in Fig. 1 (b), when people's finger contacted pole plate, human body was equivalent to ground, is equivalent to have increased pole plate area over the ground, so produced a capacitance increase Δ C (dotted line electric capacity).
The operation principle of capacitive touch sensors is responded to this capacitance increase Δ C exactly, and it is converted to data for processor processing.Present capacitance sensor has method of charge transfer, relaxation oscillations counting method and sigma-delta ADC method.These methods have its advantage separately, but the ubiquity complex structure, shortcoming such as power consumption is big, and the processing time is long, and peripheral cell is many.The capacitance sensor key is the variable quantity of inductance capacitance, and need not its capacitance of accurate measurement.
For this reason, existing capacitance touch sensing control circuit adopt have have on the inductance capacitance variable quantity simple in structure, the constant current source charging principle touch sensitive capacitance variations of characteristics such as power consumption is little, handles in real time, and peripheral cell is few.
Be illustrated in figure 2 as capacitance touch sensing control circuit based on constant current source charging principle, it comprises current setting resistance (101), pin electric capacity (102), initial comparator (103), finish comparator (104), time-to-digit converter TDC (105), voltage buffer (106) and current mirror (107).C wherein
SBe the total capacitance at this pin place, comprise chip pin parasitic capacitance and inductance capacitance.Reference voltage VREF produces one road reference current I through voltage buffer (106) and current setting resistance (101)
1, wherein voltage buffer (106) is followed the NMOS pipe that is connected by an error amplifier and a source and is constituted.Reference current I
1Convert charging current I to by current mirror (107)
2To electric capacity R
SCharging, electric capacity R
SPin reaches nominal level V
STAThe time, initial comparator (103) upset, time-to-digit converter TDC (106) picks up counting; As electric capacity R
SPin reaches a higher nominal level V
ENDThe time, finishing comparator (104) upset, TDC finishes timing.This time interval is converted into data and gives processor processing.
T1＝(V
END-V
STA)C
S/I
2
I2＝mI
1＝mV
REF/R
S
T1＝R
SC
S*(V
END-V
STA)/mV
REF
Wherein m is the mirror image coefficient of current mirror, voltage V
END, V
STAAnd V
REFProduce by same reference voltage dividing potential drop, so (V
END-V
STA)/mV
REFBe constant, establishing this constant is β.
T1＝βR
SC
S
T2＝βR
S(ΔC+C
S)
ΔT＝T2-T1＝βR
SΔC
As shown in Figure 3, Charge Line1 and Charge Line2 are respectively the charging curves before and after the expression inductance capacitance changes, and this charging process has been described.
In the practical application, staff touches the about 1pF of capacitance variations that can cause, that is to say Δ C=1pF.The about 10pF of chip pin parasitic capacitance, the about 5pF of outside inductance capacitance, the reading of Δ T are 1/16 of T2 reading; Pin parasitic capacitance and inductance capacitance may be bigger under some situation, and the capacitance variations that the staff touch causes may be littler, need from this small capacitance variations to obtain relatively large reading in the more senior application such as slip induction or absolute position judgement, that is to say the precision of inductance capacitance variation that need be very high.But resistance is set can not be got too big, because too little electric current is interfered easily, the reading of time-to-digit converter TDC also has the restriction of a location number, is difficult to realize high accuracy so existing capacitance touch sensing control circuit structure is responded to small capacitance variations under the bigger situation of natural capacity value.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of high precision capacitance touching induction control circuit framework, adopts constant current source charging principle touch sensitive capacitance variations, has realized the high accuracy that inductance capacitance changes.
Technical problem to be solved by this invention can be achieved through the following technical solutions:
A kind of high precision capacitance touching induction control circuit framework, it comprises voltage buffer, current setting resistance, current mirror, initial comparator, finishes comparator and time-to-digit converter, it is characterized in that it also comprises induction pin equivalent capacity and low reference pin equivalent capacity; Described reference voltage produces reference current by voltage buffer and current setting resistance, and described reference current produces charging current respectively to described induction pin equivalent capacity and the charging of low reference pin equivalent capacity by current mirror; The low reference pin equivalent capacity excites described initial comparator, and time-to-digit converter picks up counting, and excites described end comparator by induction pin equivalent capacity, and time-to-digit converter finishes timing and will convert transfer of data the time interval to give processor processing.
Described voltage buffer is followed the NMOS pipe that is connected by error amplifier and source and is constituted, the positive pole of described reference voltage error originated from input amplifier in, the output of error amplifier is connected with the grid of described NMOS pipe, the drain electrode of NMOS pipe inserts described current mirror, source electrode is connected with the negative pole of described error amplifier input, insert an end of described current setting resistance then, the other end ground connection of current setting resistance.
Described induction pin equivalent capacity comprises parasitic capacitance I and inductance capacitance, and described low reference pin equivalent capacity comprises parasitic capacitance II and reference capacitance, and described current mirror is made up of metal-oxide-semiconductor MP1, MP2, MP3; The source electrode of metal-oxide-semiconductor MP1, MP2, MP3 is connected to each other, and the grid of MP1, MP2, MP3 is connected to each other, and inserts respectively then in the drain electrode of NMOS pipe in the drain electrode of metal-oxide-semiconductor MP1 and the described voltage buffer; One end of described parasitic capacitance I and inductance capacitance is ground connection respectively, after being connected to each other, the other end inserts the drain electrode of metal-oxide-semiconductor MP2 and the positive pole of end comparator input terminal respectively, described parasitic capacitance II and reference capacitance one end be ground connection respectively, inserts the drain electrode of metal-oxide-semiconductor MP3 and the positive pole of initial comparator input terminal after the other end is connected to each other respectively.
The negative pole of described initial comparator and end comparator input terminal meets reference voltage V respectively
COMP, the STA and the END end of output difference digital quantizer input turn-on time of initial comparator and end comparator, the output termination processor of time-to-digit converter.
In actual applications, consider and need two reference voltages among the present invention, the fluctuation of supply voltage simultaneously also can be disturbed charging current and time-to-digit converter, for the interference on the isolating exterior power supply, insert a low drop out voltage regurator at described voltage buffer, initial comparator with before finishing comparator, it is made of a reference source, amplifier, metal-oxide-semiconductor and resistance, and described a reference source inserts the negative pole of amplifier in, and the output of amplifier is connected with the grid of metal-oxide-semiconductor; External power source inserts the source electrode of metal-oxide-semiconductor, the drain electrode of metal-oxide-semiconductor connects three resistance successively, the other end ground connection of resistance, and the positive pole of amplifier in inserts reference voltage end, give inner clean stable power, a reference source obtains two reference voltages by electric resistance partial pressure simultaneously.
In order to select it is simultaneously to each pin electric capacity charging or respectively to each pin electric capacity charging, in the present invention, comprise that also a n selects 1 gate, its input is connected with many group induction pin equivalent capacitys, and its output is connected with the positive pole that finishes comparator input terminal.
Principle of the present invention is as follows:
Provide reference capacitance C by the low reference pin equivalent capacity
REF, induction pin equivalent capacity provides inductance capacitance C
SENSOR, as reference capacitance C
REFValue reach the comparative level V of initial comparator
COMPThe time, time-to-digit converter picks up counting, as inductance capacitance C
SENSORValue reach the comparative level V that finishes comparator
COMPThe time, the time-to-digit converter timing finishes, and capacitance is converted into time quantum; But time-to-digit converter is converted into the deal with data input processor at last with time quantum; The data of double sampling will produce a time difference Δ T, and this value is promptly reacted inductance capacitance and changed.
T1＝V
COMP(C
SENSOR-C
REF)/I
2
I
2＝mI
1＝mV
REF/R
S
T1＝R
S(C
SENSOR-C
REF)V
COMP/mV
REF
Wherein m is the mirror image coefficient of current mirror, voltage V
COMPAnd V
REFProduce by a reference voltage dividing potential drop, so V
COMP/ mV
REFBe constant, establishing this constant is K.
T1＝KR
S(C
SENSOR-C
REF)
T2＝KR
S(ΔC+C
SENSOR-C
REF)
ΔT＝T2-T1＝KR
SΔC
Because the low reference pin equivalent capacity is less, reaches comparative level V at first
COMP, time-to-digit converter picks up counting.When the induction pin voltage is charged to V
COMPThe time, time-to-digit converter finishes timing and is designated as T1.When capacitance variations, repeat a process, the time-to-digit converter reading is designated as T2.Twice Measuring Time difference Δ T=T2-T1, the reaction capacitance variations.
Suppose that parasitic capacitance is 10pF, inductance capacitance 5pF, reference capacitance 4.5pF, Δ C are 1pF.The reading of Δ T is 2/3 of a T2 reading.
From the above, the pin parasitic capacitance is offset fully, excessive inductance capacitance C
SENSORAlso can rely on a rational reference capacitance C is set
REFOffset significantly.The proportion that the variation delta C of inductance capacitance accounts for timing electric capacity is very big, so the minor variations of electric capacity also can obtain a bigger time-to-digit converter reading, has so just realized the high accuracy that inductance capacitance changes.
A kind of high precision capacitance touching induction control circuit framework of the present invention has following advantage:
1, simple in structure, power consumption is little, handles in real time, and peripheral cell is few.
2, the resistance capacitance value is converted to a time quantum, and this time quantum is only on duty long-pending relevant with resistance capacitance, and irrelevant with supply voltage and reference voltage, regulates non-essential resistance and can regulate induction precision.
3, when suitable reference capacitance being set make measuring electric capacity, intrinsic pin parasitic capacitance and inductance capacitance are offset by major part, and capacitance change reading proportion is exaggerated, and induction precision improves.
Description of drawings
Further specify the present invention below in conjunction with the drawings and specific embodiments.
Fig. 1 (a) is the schematic diagram of inductance capacitance;
Fig. 1 (b) is the schematic diagram of touch sensible electric capacity;
Fig. 2 is existing a kind of capacitance touching induction control circuit framework schematic diagram;
Fig. 3 is the schematic diagram of the work schedule waveform of existing a kind of capacitance touch sensing control circuit;
Fig. 4 is the schematic diagram of a kind of high precision capacitance touching induction control circuit framework of the present invention;
Fig. 5 is the schematic diagram of the work schedule waveform of circuit of the present invention;
Fig. 6 is the low drop out voltage regurator schematic diagram that produces operating voltage and reference voltage among the present invention;
Fig. 7 is the schematic diagram of another kind of high precision capacitance touching induction control circuit framework of the present invention;
Fig. 8 (a) is the schematic diagram of multichannel inductance capacitance under different charging modes;
Fig. 8 (b) is the schematic diagram of multichannel touch sensible electric capacity under different charging modes.
Embodiment
As shown in Figure 4, a kind of high precision capacitance touching induction control circuit framework provided by the present invention, it comprises voltage buffer (206), current setting resistance (201), current mirror (207), initial comparator (203), finishes comparator (204) and time-to-digit converter (205), also comprises induction pin equivalent capacity (202) and low reference pin equivalent capacity (208); Reference voltage produces reference current by voltage buffer (206) and current setting resistance (201), and described reference current produces charging current respectively to induction pin equivalent capacity (202) and low reference pin equivalent capacity (208) charging by current mirror (207); Low reference pin equivalent capacity (208) excites initial comparator (203), time-to-digit converter picks up counting, excite end comparator (204) by induction pin equivalent capacity (202), time-to-digit converter (205) finishes timing and will convert transfer of data the time interval to give processor processing.
Induction pin equivalent capacity (202) comprises parasitic capacitance C
PARAWith inductance capacitance C
SENSORLow reference pin equivalent capacity (208) comprises parasitic capacitance C
PARAWith reference capacitance C
REF, reference capacitance C
REFValue must be less than inductance capacitance C
SENSORValue.Reference voltage V
REFProduce one road reference current I through voltage buffer (206) and current setting resistance (201)
1, wherein voltage buffer (206) is followed the NMOS pipe that is connected by an error amplifier and a source and is constituted.Reference current I
1Convert the charging current I that two-way equates to by current mirror (207)
2, I
3Simultaneously to inductance capacitance C
SENSORWith reference capacitance C
REFCharging, reference capacitance C
REFPin reaches specified comparative level V
COMPThe time, initial comparator (203) upset, time-to-digit converter TDC (206) picks up counting; As inductance capacitance C
SENSORPin reaches nominal level V
COMPThe time, finishing comparator (204) upset, time-to-digit converter TDC (206) finishes timing; This time interval is converted into data and gives processor processing.
Capacitance is converted into time quantum, but time quantum is converted into deal with data at last.If inductance capacitance C
SENSORValue changes, and the TDC data of double sampling will produce a time difference Δ T, and this value is promptly reacted inductance capacitance C
SENSORChange.
T1＝V
COMP(C
SENSOR-C
REF)/I
2
I2＝mI
1＝mV
REF/R
S
T1＝R
S(C
SENSOR-C
REF)V
COMP/mV
REF
Wherein m is the mirror image coefficient of current mirror (207), voltage V
COMPAnd V
REFProduce by a reference voltage dividing potential drop, so V
COMP/ mV
REFBe constant, establishing this constant is K.
T1＝KR
S(C
SENSOR-C
REF)
T2＝KR
S(ΔC+C
SENSOR-C
REF)
ΔT＝T2-T1＝KR
SΔC
Fig. 5 has illustrated this charging process.Because low reference pin equivalent capacity (208) is less, Charge Ref reaches comparative level V at first
COMP, time-to-digit converter TDC (206) picks up counting.As inductance capacitance C
SENSORPin voltage is charged to V
COMPThe time, seeing Charge Line1, time-to-digit converter TDC (206) finishes timing and is designated as T1.As inductance capacitance C
SENSORDuring variation, repeat a process, Charge Line2 represents inductance capacitance C
SENSORPin voltage, time-to-digit converter TDC (206) reading is designated as T2.Twice Measuring Time difference Δ T=T2-T1, reaction inductance capacitance C
SENSORChange.
Suppose parasitic capacitance C
PARABe 10pF, inductance capacitance C
SENSORBe 5pF, reference capacitance C
REFBe 4.5pF, Δ C is 1pF.The reading of Δ T is 2/3 of a T2 reading.
Easily know by figure and formula: parasitic capacitance C
PARAOffset excessive inductance capacitance C fully
SENSORAlso can rely on a rational reference capacitance C is set
REFOffset significantly.Inductance capacitance C
SENSORVariation delta C to account for the proportion of timing electric capacity very big, so inductance capacitance C
SENSORMinor variations also can obtain bigger time-to-digit converter TDC (a 206) reading, so just realized inductance capacitance C
SENSORThe high accuracy that changes.
We are also referred to as baseline the data D1 that time quantum T1 elapsed time digital quantizer TDC (206) shown in Figure 5 converts to, change inductance capacitance C when staff touches
SENSORObtain the data D2 that T2 converts to, the poor Δ D of D2 and D1 promptly is processed into effective button.Practical application is different from above-mentioned ideal situation, because inductance capacitance C
SENSORMay change as conditions such as temperature humidity with external environment condition, will cause the fluctuation of baseline like this.And different people or finger are done the difference that the difference of wet degree also can cause Δ D.This just needs processor that these data are done special processing, (data processing will adopt baseline to follow the tracks of, and thresholding is differentiated, technology such as multiple averaging can correctly whether to identify touch under the situation of getting rid of external interference, owing to exceed this patent scope, no longer be described in detail).
As shown in Figure 6, in actual applications, considering needs two reference voltage V among the present invention
REFAnd V
COMP, the fluctuation of supply voltage VDD simultaneously also can be disturbed charging current I
2, I
3With time-to-digit converter TDC (206), for the interference on the isolating exterior power supply DVDD, insert a low drop out voltage regurator before at voltage buffer (206), initial comparator (203) and end comparator (204), it is made of a reference source BANDGAP, amplifier EA, metal-oxide-semiconductor and resistance, a reference source BANDGAP inserts the negative pole of amplifier EA input, and the output of amplifier EA is connected with the grid of metal-oxide-semiconductor; External power source DVDD inserts the source electrode of metal-oxide-semiconductor, and the drain electrode of metal-oxide-semiconductor connects three resistance successively, the other end ground connection of resistance, and the positive pole of amplifier EA input inserts reference voltage V
REFEnd is given inner clean stable power, and a reference source BANDGAP obtains reference voltage V by electric resistance partial pressure simultaneously
REF, V
COMPUse with supply voltage VDD voltage supplied buffer (206), initial comparator (203) and end comparator (204).
Fig. 7 is a kind of multi-channel capacitive touch sensing control circuit.Comprise current setting resistance (301), some induction pin equivalent capacitys (302), initial comparator (303), finish comparator (304), time-to-digit converter TDC (305), voltage buffer (306), multichannel current mirror (307), low reference pin equivalent capacity (308) and n select 1 gate (309).N selects 1 gate (309) to choose an inductance capacitance path at every turn, that is to say that some moment have only a charging path to be taken as end signal, and other operation principle is described with Fig. 4 structure.
Here the multichannel charging scheme adopts multichannel current mirror (307) to also have an extra benefit, and a plurality of passages can be selected simultaneously to each pin electric capacity charging or respectively to each pin electric capacity charging.Fig. 8 (a) has described pin equivalent capacity when charging respectively, this electric capacity comprises various parasitic capacitances and inductance capacitance, because in the practical application, chip pin, cabling, induction pole Board position approaching is when this pin current potential rises, close on pin and keep relative electronegative potential, this potential difference must cause this pin and close on having parasitic capacitance between the pin.Dotted line electric capacity is the capacitance increase Δ C (dotted line electric capacity) after staff touches.Fig. 8 (b) has described pin equivalent capacity when charging simultaneously, because this pin and close on pin and do not have potential difference so natural capacity reduces, when staff touches, becomes big when the contact area of equivalence charges more respectively, incremental capacitance becomes greatly.The natural capacity reading diminishes, and electric capacity change amount reading is further amplified, and has improved induction precision.
More than show and described basic principle of the present invention and principal character and advantage thereof.The technical staff of the industry should understand; the present invention is not restricted to the described embodiments; that describes in the foregoing description and the specification just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.
Claims (6)
1, a kind of high precision capacitance touching induction control circuit framework, it comprises voltage buffer, current setting resistance, current mirror, initial comparator, finishes comparator and time-to-digit converter, it is characterized in that it also comprises induction pin equivalent capacity and low reference pin equivalent capacity; Reference voltage V
REFBe connected with the input of voltage buffer, current setting resistance is connected with output with the input of voltage buffer respectively, reference voltage V
REFProduce reference current by voltage buffer and current setting resistance, the output of voltage buffer is connected with the input of current mirror, the output of current mirror is connected with the low reference pin equivalent capacity with induction pin equivalent capacity, and described reference current produces charging current by current mirror and respectively described induction pin equivalent capacity and low reference pin equivalent capacity charged; The low reference pin equivalent capacity is connected with initial comparator, excite described initial comparator, initial comparator is connected with time-to-digit converter, time-to-digit converter picks up counting, be connected with the end comparator by induction pin equivalent capacity, excite described end comparator, finish comparator and be connected with time-to-digit converter, time-to-digit converter finishes timing and will convert transfer of data the time interval to give processor processing.
2, high precision capacitance touching induction control circuit framework according to claim 1 is characterized in that: described voltage buffer is followed the NMOS pipe that is connected by error amplifier and source and is constituted described reference voltage V
REFThe positive pole of error originated from input amplifier in, the output of error amplifier is connected with the grid of described NMOS pipe, the drain electrode of NMOS pipe inserts described current mirror, the source electrode of described NMOS pipe is connected with the negative pole of described error amplifier input, insert an end of described current setting resistance then, the other end ground connection of current setting resistance.
3, high precision capacitance touching induction control circuit framework according to claim 1, it is characterized in that: described induction pin equivalent capacity comprises parasitic capacitance I and inductance capacitance, described low reference pin equivalent capacity comprises parasitic capacitance II and reference capacitance, and described current mirror is made up of metal-oxide-semiconductor MP1, metal-oxide-semiconductor MP2, metal-oxide-semiconductor MP3; The source electrode of metal-oxide-semiconductor MP1, metal-oxide-semiconductor MP2, metal-oxide-semiconductor MP3 is connected to each other, and the grid of metal-oxide-semiconductor MP1, metal-oxide-semiconductor MP2, metal-oxide-semiconductor MP3 is connected to each other, and inserts respectively then in the drain electrode of NMOS pipe in the drain electrode of metal-oxide-semiconductor MP1 and the described voltage buffer; One end of described parasitic capacitance I and inductance capacitance is ground connection respectively, after being connected to each other, the other end inserts the drain electrode of metal-oxide-semiconductor MP2 and the positive pole of end comparator input terminal respectively, described parasitic capacitance II and reference capacitance one end be ground connection respectively, inserts the drain electrode of metal-oxide-semiconductor MP3 and the positive pole of initial comparator input terminal after the other end is connected to each other respectively.
4, high precision capacitance touching induction control circuit framework according to claim 1, it is characterized in that: the negative pole of described initial comparator and end comparator input terminal meets reference voltage VCOMP respectively, the STA and the END end of output difference digital quantizer input turn-on time of initial comparator and end comparator, the output termination processor of time-to-digit converter.
5, high precision capacitance touching induction control circuit framework according to claim 4, it is characterized in that: insert a low drop out voltage regurator at described voltage buffer, initial comparator with before finishing comparator, it is made of a reference source, amplifier, metal-oxide-semiconductor and resistance, described a reference source inserts the negative pole of amplifier in, and the output of amplifier is connected with the grid of metal-oxide-semiconductor; External power source inserts the source electrode of metal-oxide-semiconductor, and the drain electrode of metal-oxide-semiconductor connects three resistance successively, the other end ground connection of resistance, and the positive pole of amplifier in inserts reference voltage end.
6, high precision capacitance touching induction control circuit framework according to claim 4, it is characterized in that: it comprises that also a n selects 1 gate, its input is connected with many group induction pin equivalent capacitys, and its output is connected with the positive pole that finishes comparator input terminal.
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| CNB2007100379766A CN100566164C (en) | 2007-03-12 | 2007-03-12 | A kind of high precision capacitance touching induction control circuit framework |
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|---|---|---|---|
| CNB2007100379766A CN100566164C (en) | 2007-03-12 | 2007-03-12 | A kind of high precision capacitance touching induction control circuit framework |
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| CN100566164C true CN100566164C (en) | 2009-12-02 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101847070B (en) * | 2010-03-23 | 2011-10-05 | 敦泰科技(深圳)有限公司 | Capacitance change detection module taking electric signal change time as detection target |
| CN102890575B (en) * | 2011-07-22 | 2016-09-14 | 国民技术股份有限公司 | A kind of touch sensible positioner and system |
| CN102411393B (en) * | 2011-11-02 | 2013-10-02 | 四川和芯微电子股份有限公司 | Reference current source circuit and system |
| CN102571049B (en) * | 2011-12-20 | 2013-12-04 | 利尔达科技集团股份有限公司 | Anti-interference circuit and anti-interference method for touch key of induction cooker |
| CN103905024A (en) * | 2012-12-27 | 2014-07-02 | 北京谊安医疗系统股份有限公司 | Button circuit for improving sensitivity of capacitance induction button, and compensation circuit and compensation method thereof |
| CN104092372B (en) * | 2014-06-30 | 2017-04-12 | 成都芯源系统有限公司 | Switch regulating circuit and mean current detection circuit and method thereof |
| US10578461B2 (en) * | 2016-01-06 | 2020-03-03 | Disuptive Technologies Research AS | Capacitive sensor readout circuit |
| CN111273540B (en) * | 2020-04-15 | 2022-06-28 | 河南广播电视大学 | Wireless timing system based on zigbee communication and Beidou dual-mode time service |
| CN112953220B (en) * | 2021-02-03 | 2022-12-30 | 电子科技大学 | DC-DC converter with current sensing and control |
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