CN103873026A - Sensing circuit - Google Patents
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- CN103873026A CN103873026A CN201210525330.3A CN201210525330A CN103873026A CN 103873026 A CN103873026 A CN 103873026A CN 201210525330 A CN201210525330 A CN 201210525330A CN 103873026 A CN103873026 A CN 103873026A
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Abstract
The invention provides a sensing circuit which comprises a sensor, a first amplifying circuit, a high-pass filter, a second amplifying circuit and a judging circuit. The sensor is used for generating a sensing signal. The first amplifying circuit is used for filtering a high-frequency signal in the sensing signal and amplifying a low-frequency signal in the sensing signal to generate a first amplifying signal. The high-pass filter is used for filtering a direct-current signal in the first amplifying signal to generate a filter signal. The second amplifying circuit is used for amplifying a low-frequency signal in the filter signal according to a first predetermined voltage to generate a second amplifying signal. The judging circuit is used for judging the second amplifying signal, and generating a detection result when the second amplifying signal is greater than a second predetermined voltage or smaller than a third predetermined voltage. The sensing circuit of the invention has a smaller size, better stability and better inhibiting capability.
Description
Technical field
The present invention is about a kind of sensing circuit, especially in regard to a kind of sensing circuit that does not need large electric capacity to carry out filtering.
Background technology
In recent years, electronic installation become more and more high-order and function also more and more diversified.For instance, similar can possess various sensing apparatus as electronic installations such as mobile phone, computer or household electrical appliance, to implement corresponding application according to different environmental parameters.
Current sensing apparatus is many is need to detect 0.4Hz ~ 7Hz to the low frequency signal of human motion in environment, for example pyroelectric type infrared detector.But the filter circuit that existing low frequency sensing apparatus all need to be made up of the electric capacity of the resistance of large resistance and large capacitance, carries out filtering to received signal, make sensing result more accurate and avoid the misoperation of circuit.Generally speaking, the filter circuit being made up of the resistance of large resistance and the electric capacity of large capacitance needs the time about 30 seconds after system boot, just can have stable detecting function.In addition, the electric capacity of large capacitance also needs larger circuit layout area, causes the inconvenience in product design.Large electric capacity also has after long-term use in addition, can produce leaky.In view of this, the invention provides a kind of sensing circuit, to solve described problem.
Summary of the invention
Sensing circuit provided by the present invention can use the circuit without large electric capacity and autobias, and the signal of detecting low frequency also improves the inhibition ability at high frequency.
The invention provides a kind of sensing circuit.Sensing circuit comprises a transducer, one first amplifying circuit, a high pass filter, one second amplifying circuit and a decision circuitry.Transducer is in order to produce a sensing signal.The first amplifying circuit is in order to produce autobias and filter the high-frequency signal in sensing signal and amplify the low frequency signal in sensing signal, to produce one first amplifying signal.High pass filter is in order to filter the direct current signal in the first amplifying signal, to produce a filtering signal.The second amplifying circuit, in order to do bias voltage according to one first set voltage, amplifies the low frequency signal in the first amplifying signal and refilters the high-frequency signal in the first amplifying signal, to produce one second amplifying signal.Decision circuitry is in order to judge whether the second amplifying signal is greater than one second set voltage, judge whether the second amplifying signal is less than one the 3rd set voltage, and in the time that the second amplifying signal is greater than the second set voltage or is less than the 3rd set voltage, produce a detecting result.
The present invention has less volume, stability and suppress preferably ability preferably.
Brief description of the drawings
Fig. 1 is the calcspar of a kind of sensing circuit provided by the present invention;
Fig. 2 is the calcspar of a kind of the first amplifying circuit provided by the present invention;
Fig. 3 is the calcspar of a kind of low pass filter provided by the present invention;
Fig. 4 is the calcspar of a kind of high pass filter provided by the present invention;
Fig. 5 is the calcspar of a kind of the second amplifying circuit provided by the present invention;
Fig. 6 is the calcspar of a kind of decision circuitry provided by the present invention;
Fig. 7 is the calcspar of a kind of voltage generator provided by the present invention; And
Fig. 8 is the calcspar of a kind of sensing circuit provided by the present invention; And
Fig. 9 is the signal simulation figure of sensing circuit provided by the present invention.
Symbol in accompanying drawing is simply described as follows:
100: sensing circuit; 110: transducer; 120: the first amplifying circuits; 122: low pass filter; 124: the first amplifiers; 130: high pass filter; CF: filter capacitor; 140: the second amplifying circuits; 142: the second amplifiers; 150: decision circuitry; 152,154: comparator; 156: or door; 160: voltage generator; 162: bleeder circuit; 164: unity gain buffer; 802,804: frequency response; OP1: amplifier; C1-C3: electric capacity; R1-R7: resistance; Rd1-Rd4: divider resistance; SS1: sensing signal; AS1: the first amplifying signal; FS1: filtering signal; AS2: the second amplifying signal; DR1: detecting result; And VM, VH, VL: the first set voltage; Vref: reference voltage; And GND: ground connection.
Embodiment
Device and the using method of various embodiments of the invention will be discussed in detail below.But it should be noted that many feasible inventive concepts provided by the present invention may be implemented in various particular ranges.These specific embodiments are only for illustrating device of the present invention and using method, but non-for limiting scope of the present invention.
Fig. 1 is the calcspar of a kind of sensing circuit provided by the present invention.Sensing circuit 100 comprises a transducer 110, one first amplifying circuit 120, a high pass filter 130, one second amplifying circuit 140, a decision circuitry 150 and a voltage generator 160.Those skilled in the art also can be implemented on sensing circuit 100 one to be had in the computer system sample state (configuration) of sensing function, for example, portable equipment (hand-helddevices), multicomputer system, taking microprocessor as basis or the consumption electronic products of programmable (microprocessor-based or programmable consumerelectronics), surveillance video equipment, household electrical appliance and similar equipment, the present invention is not limited.
The first amplifying circuit 120 is coupled between transducer 110 and high pass filter 130, the sensing signal SS1 producing in order to receiving sensor 110.In addition, the first amplifying circuit 120 more, in order to filter the high-frequency signal in sensing signal SS1 and to amplify the low frequency signal in sensing signal SS1, to produce one first amplifying signal AS1, and is sent to high pass filter 130 by the first amplifying signal AS1.
The second amplifying circuit 140 is coupled between high pass filter 130, voltage generator 160 and decision circuitry 150.The one first set voltage VM of the second amplifying circuit 140 in order to produce according to voltage generator 160, the low frequency signal in amplification filtering signal FS1, to produce one second amplifying signal AS2.The second amplifying circuit 140 is more in order to be sent to decision circuitry 150 by the second amplifying signal AS2.
Fig. 2 is the calcspar of a kind of the first amplifying circuit 120 provided by the present invention.In the present embodiment, the first amplifying circuit 120 comprises a low pass filter 122, one first resistance R 1, one first amplifier 124, one second resistance R 2, one first capacitor C 1 and one the 4th resistance R 4.Low pass filter 122 has a first end and is coupled to a first node N1 and one second end and is coupled to the positive input terminal of the first amplifier 124, in order to filter the high-frequency signal in sensing signal SS1.The first resistance R 1 has that a first end is coupled to first node N1 and one second end is coupled to a Section Point N2.The second resistance R 2 has a first end and is coupled to Section Point N2 and one second end and is coupled to the output of the first amplifier 124.The first amplifier 124 has a positive input terminal and is coupled to the second end of low pass filter 122, one negative input end is coupled to Section Point N2 and an output in order to produce the first amplifying signal AS1, and wherein the first amplifier 124 is in order to amplify the low frequency signal in sensing signal SS1 according to the ratio of the resistance of the first resistance R 1 and the second resistance R 2.In an embodiment in the present invention, the resistance of the second resistance R 2 is 100 times of resistance of the first resistance R 1.For example, the resistance of the first resistance R 1 can be 10 kilooersted nurses (K Ω), and the resistance of the second resistance R 2 can be 1000 kilooersted nurses (K Ω), but the invention is not restricted to this.It should be noted that in the present embodiment, the low frequency signal in sensing signal SS1 is amplified 100 times by the first amplifier 124.The first capacitor C 1 has a first end and is coupled to first node N1 and one second end and is coupled to the output of the first amplifier 124, in order to receive the high-frequency signal in sensing signal SS1, the high-frequency signal in sensing signal SS1 can not amplified by the first amplifier 124.In one embodiment of this invention, the capacitance of the first capacitor C 1 can be 0.1 microfarad (μ F), but the invention is not restricted to this.In other embodiments, also to can be other capacitance little and in order to the electric capacity of conducting high-frequency signal for the first capacitor C 1.The 4th resistance R 4 is coupled between the positive input terminal and negative input end of the first amplifier 124.
Fig. 3 is the calcspar of a kind of low pass filter 122 provided by the present invention.In the present embodiment, low pass filter 122 comprises one the 3rd resistance R 3 and one second capacitor C 2, but the invention is not restricted to this.The 3rd resistance R 3 has a first end and is coupled to first node N1 and one second end and is coupled to the positive input terminal of the first amplifier 124.The second capacitor C 2 has the second end and one second end that a first end is coupled to the 3rd resistance R 3 and is coupled to a ground connection GND.In one embodiment of this invention, the resistance of the 3rd resistance R 3 is 200 kilooersted nurses (K Ω), and the capacitance of the second capacitor C 2 is 2.2 microfarads (μ F), but the invention is not restricted to this.
Fig. 4 is the calcspar of a kind of high pass filter 130 provided by the present invention.In the present embodiment, high pass filter 130 comprises one the 7th resistance R 7 and a filter capacitor CF.Filter capacitor CF has a first end and is coupled to the first amplifying circuit 120 and one second end and is coupled to the second end and second amplifying circuit 140 of the 7th resistance R 7, wherein filter capacitor CF is in order to filter the direct current signal in the first amplifying signal AS1, to produce a filtering signal FS1, and filtering signal FS1 is sent to the second amplifying circuit 140.For example, the capacitance of filter capacitor CF can be 1 microfarad (μ F).The 7th resistance R 7 has a first end and is coupled to one the 3rd node N3, be coupled to the second amplifying circuit 140 in order to receive the first set voltage VM and one second end, wherein the 7th resistance R 7 improves the voltage of filtering signal FS1 in order to the first set voltage VM producing by voltage generator 160.It should be noted that the second end of the 7th resistance R 7 is coupled to the positive input terminal of one second amplifier 142 in the second amplifying circuit 140, as shown in Figure 8.In one embodiment of this invention, the 7th resistance R 7 is 400 kilooersted nurses (K Ω), but the invention is not restricted to this.
Fig. 5 is the calcspar of a kind of the second amplifying circuit 140 provided by the present invention.In the present embodiment, the second amplifying circuit 140 comprises one the 5th resistance R 5, one second amplifier 142, one the 6th resistance R 6, one the 3rd capacitor C 3.The 5th resistance R 5 has a first end and is coupled to one the 3rd node N3, and the first set voltage VM producing in order to receiver voltage generator 160 and one second end are coupled to the negative input end of the second amplifier 142.The 6th resistance R 6 has a first end and is coupled to the negative input end of the second amplifier 142 and one second end and is coupled to the output of the second amplifier 142.The second amplifier 142 has a positive input terminal and is coupled to high pass filter 130, in order to the signal FS1 that accepts filter, one negative input end is coupled to the second end of the 5th resistance R 5 and an output in order to produce the second amplifying signal AS2, and wherein the second amplifier 142 is in order to according to the low frequency signal in the ratio amplification filtering signal FS1 of the resistance of the 5th resistance R 5 and the 6th resistance R 6.In an embodiment in the present invention, the resistance of the 5th resistance R 5 is 25 times of resistance of the 6th resistance R 6.For example, the resistance of the 5th resistance R 5 can be 20 kilooersted nurses (K Ω), and the resistance of the 6th resistance R 6 can be 500 kilooersted nurses (K Ω), but the invention is not restricted to this.It should be noted that in the present embodiment, the low frequency signal in filtering signal FS1 is amplified 25 times by the second amplifier 142.The 3rd capacitor C 3 has a first end and is coupled to the negative input end of the second amplifier 142 and one second end and is coupled to the output of the second amplifier 142, in order to the high-frequency signal accepting filter in signal FS1, the high-frequency signal in filtering signal FS1 can not amplified by the second amplifier 142.In one embodiment of this invention, the capacitance of the 3rd capacitor C 3 can be 0.022 microfarad (μ F), the invention is not restricted to this.In other embodiments, also to can be other capacitance little and in order to the electric capacity of conducting high-frequency signal for the 3rd capacitor C 3.
Fig. 6 is the calcspar of a kind of decision circuitry 150 provided by the present invention.In the present embodiment, decision circuitry 150 comprises one first comparator 152, one second comparator 154 and one or door 156, but the invention is not restricted to this.The first comparator 152 has a positive input terminal in order to receive the second amplifying signal AS2, the second set voltage VH that one negative input end produces in order to receiver voltage generator 160 and an output is coupled to or door 156, in order to judge whether the second amplifying signal AS2 is greater than the second set voltage VH.The second comparator 154 has the 3rd set voltage VL that a positive input terminal produces in order to receiver voltage generator 160, one negative input end is coupled to or door 156 in order to receive the second amplifying signal AS2 and an output, in order to judge whether the second amplifying signal AS2 is less than the 3rd set voltage VL.Or door 156 has a first input end and is coupled to the output of the first comparator 152, one second input is coupled to the output of the second comparator 154 and an output when being greater than the second set voltage VH as the second amplifying signal AS2 or being less than the 3rd set voltage VL, produces detecting result DR1.
Fig. 7 is the calcspar of a kind of voltage generator 160 provided by the present invention.In the present embodiment, voltage generator 160 comprises a bleeder circuit 162 and unity gain buffer 164.Bleeder circuit 162 comprises one first divider resistance Rd1, one second divider resistance Rd2, one the 3rd divider resistance Rd3 and one the 4th divider resistance Rd4, but the invention is not restricted to this.The first divider resistance Rd1 has a first end and is coupled to first end that a reference voltage Vref and one second end be coupled to the second divider resistance Rd2 in order to produce the second set voltage VH.The second divider resistance Rd2, has a first end and is coupled to the second end of the first divider resistance Rd1 and first end that one second end is coupled to the 3rd divider resistance Rd3 in order to produce the first set voltage VM.The 3rd divider resistance Rd3 has a first end and is coupled to the second end of the second divider resistance Rd2 and first end that one second end is coupled to the 4th divider resistance Rd4 in order to produce the 3rd set voltage VL.The 4th divider resistance Rd4 has the second end and one second end that a first end is coupled to the 3rd divider resistance Rd3 and is coupled to a ground connection GND.Unity gain buffer 164 has the second end and the output that an input is coupled to the second divider resistance Rd2 and is coupled to the second amplifying circuit 140, the electric current producing in order to amplify the first set voltage VM, and the first set voltage VM is sent to the second amplifying circuit 140.In one embodiment of this invention, unity gain buffer 164 is an amplifier OP1, have the second end that a positive input terminal is coupled to the second divider resistance Rd2, a negative input end and an output are coupled to the second amplifying circuit 140 and negative input end, but the invention is not restricted to this.
Fig. 8 is the calcspar of a kind of sensing circuit provided by the present invention.Sensing circuit 100 shown in Fig. 8 adopts the first amplifying circuit 120 shown in Fig. 2-7, high pass filter 130, the second amplifying circuit 140, decision circuitry 150 and a voltage generator 160.In the present embodiment, the capacitance of the electric capacity in sensing circuit 100 is neither greater than 5 microfarads (μ F), is even less than 3 microfarads (μ F), makes sensing circuit 100 have less volume and stability preferably compared to existing sensing circuit.Moreover because sensing circuit 100 does not have large electric capacity, therefore sensing circuit 100 can reach at short notice stable after start, with detection signal.Therefore, sensing circuit 100 provided by the present invention can accelerate manufacturers produce and test the needed time.In addition, the 4th resistance R 4, more in order to after start, is accelerated the charging rate of the second capacitor C 2, to shorten the stabilization time of sensing circuit 100.
Fig. 9 is the signal simulation figure of sensing circuit 100 provided by the present invention.Fig. 9 comprises the frequency response 804 of available circuit and the frequency response 802 of sensing circuit of the present invention 100.From frequency response 804 and frequency response 802, sensing circuit 100 is compared to existing sensing circuit, more than low frequency (0.01Hz) and high frequency (more than 10kHz) all there is good inhibition ability.
The foregoing is only preferred embodiment of the present invention; so it is not in order to limit scope of the present invention; anyone familiar with this technology; without departing from the spirit and scope of the present invention; can do on this basis further improvement and variation, therefore protection scope of the present invention is when being as the criterion with the application's the scope that claims were defined.Arbitrary embodiment of the present invention or claim must not reached the disclosed whole objects of the present invention or advantage or feature in addition.In addition, summary part and title are only the use of searching for auxiliary patent document, are not used for limiting interest field of the present invention.
Claims (10)
1. a sensing circuit, is characterized in that, comprising:
One transducer, in order to produce a sensing signal;
One first amplifying circuit, in order to filter the high-frequency signal in above-mentioned sensing signal and to amplify the low frequency signal in above-mentioned sensing signal, to produce one first amplifying signal;
One high pass filter, in order to filter the direct current signal in above-mentioned the first amplifying signal, to produce a filtering signal;
One second amplifying circuit, in order to according to one first set voltage, amplifies the low frequency signal in above-mentioned filtering signal, to produce one second amplifying signal; And
One decision circuitry, in order to judge whether above-mentioned the second amplifying signal is greater than one second set voltage, judge whether above-mentioned the second amplifying signal is less than one the 3rd set voltage, and in the time that above-mentioned the second amplifying signal is greater than above-mentioned the second set voltage or is less than above-mentioned the 3rd set voltage, produce a detecting result.
2. sensing circuit according to claim 1, is characterized in that, above-mentioned the first amplifying circuit also comprises:
One low pass filter, has a first end and is coupled to a first node and one second end;
One first resistance, has that a first end is coupled to above-mentioned first node and one second end is coupled to a Section Point;
One first amplifier, has the second end, a negative input end that a positive input terminal is coupled to above-mentioned low pass filter and is coupled to above-mentioned Section Point and an output in order to produce above-mentioned the first amplifying signal;
One second resistance, has a first end and is coupled to above-mentioned Section Point and one second end and is coupled to the output of above-mentioned the first amplifier; And
One first electric capacity, has a first end and is coupled to above-mentioned first node and one second end and is coupled to the output of above-mentioned the first amplifier.
3. sensing circuit according to claim 2, is characterized in that, above-mentioned low pass filter also comprises:
One the 3rd resistance, has a first end and is coupled to above-mentioned first node and one second end and is coupled to the positive input terminal of above-mentioned the first amplifier; And
One second electric capacity, has the second end and one second end that a first end is coupled to above-mentioned the 3rd resistance and is coupled to a ground connection.
4. sensing circuit according to claim 2, is characterized in that, above-mentioned the first amplifying circuit also comprises that one the 4th resistance is coupled between the positive input terminal and negative input end of above-mentioned the first amplifier.
5. sensing circuit according to claim 1, is characterized in that, above-mentioned the second amplifying circuit also comprises:
One the 5th resistance, has that a first end is coupled to one the 3rd node and in order to receive above-mentioned the first set voltage and one second end;
One second amplifier, has a positive input terminal and is coupled to above-mentioned high pass filter and is coupled to the second end of above-mentioned the 5th resistance and an output in order to produce above-mentioned the second amplifying signal in order to receive above-mentioned filtering signal, a negative input end;
One the 6th resistance, has a first end and is coupled to the negative input end of above-mentioned the second amplifier and one second end and is coupled to the output of above-mentioned the second amplifier; And
One the 3rd electric capacity, has a first end and is coupled to the negative input end of above-mentioned the second amplifier and one second end and is coupled to the output of above-mentioned the second amplifier.
6. sensing circuit according to claim 1, is characterized in that, also comprises a voltage generator, in order to produce above-mentioned the first set voltage, above-mentioned the second set voltage and above-mentioned the 3rd set voltage.
7. sensing circuit according to claim 6, is characterized in that, above-mentioned voltage generator also comprises:
One bleeder circuit, comprising:
One first divider resistance, has a first end and is coupled to a reference voltage and one second end in order to produce above-mentioned the second set voltage;
One second divider resistance, has a first end and is coupled to the second end of above-mentioned the first divider resistance and one second end in order to produce above-mentioned the first set voltage;
One the 3rd divider resistance, has a first end and is coupled to the second end of above-mentioned the second divider resistance and one second end in order to produce above-mentioned the 3rd set voltage; And
One the 4th divider resistance, has the second end and one second end that a first end is coupled to above-mentioned the 3rd divider resistance and is coupled to a ground connection; And
One unity gain buffer, has the second end and the output that an input is coupled to above-mentioned the second divider resistance and is coupled to above-mentioned the second amplifying circuit.
8. sensing circuit according to claim 1, is characterized in that, above-mentioned decision circuitry also comprises:
One first comparator, has a positive input terminal in order to receive above-mentioned the second amplifying signal, a negative input end in order to receive above-mentioned the second set voltage and an output;
One second comparator, has a positive input terminal in order to receive above-mentioned the 3rd set voltage, a negative input end in order to receive above-mentioned the second amplifying signal and an output; And
One or door, there is output that a first input end is coupled to above-mentioned the first comparator, output that one second input is coupled to above-mentioned the second comparator and an output in order to produce above-mentioned detecting result.
9. sensing circuit according to claim 1, is characterized in that, above-mentioned high pass filter also comprises:
One the 7th resistance, has a first end and is coupled to one the 3rd node and is coupled to above-mentioned the second amplifying circuit in order to receive above-mentioned the first set voltage and one second end; And
One filter capacitor, has a first end and is coupled to above-mentioned the first amplifying circuit and one second end and is coupled to the second end of above-mentioned the 7th resistance.
10. sensing circuit according to claim 1, is characterized in that, above-mentioned the first set voltage is the mean value of above-mentioned the second set voltage and above-mentioned the 3rd set voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210525330.3A CN103873026A (en) | 2012-12-07 | 2012-12-07 | Sensing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210525330.3A CN103873026A (en) | 2012-12-07 | 2012-12-07 | Sensing circuit |
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| CN103873026A true CN103873026A (en) | 2014-06-18 |
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| CN201210525330.3A Pending CN103873026A (en) | 2012-12-07 | 2012-12-07 | Sensing circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105763182A (en) * | 2014-12-16 | 2016-07-13 | 华硕电脑股份有限公司 | Signal analysis circuit and signal analysis method |
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|---|---|---|---|---|
| US6060952A (en) * | 1998-11-02 | 2000-05-09 | Atsumi Electric Co., Ltd. | Amplifier circuit for infrared sensor |
| US6246282B1 (en) * | 1998-11-05 | 2001-06-12 | Nec Corporation | First stage amplifier circuit |
| US20050258884A1 (en) * | 2004-05-18 | 2005-11-24 | Li-Te Wu | [dc level wandering cancellation circuit] |
| CN2819235Y (en) * | 2005-03-09 | 2006-09-20 | 湖南科技大学 | On-line quality state monitoring system of electromagnetic component |
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2012
- 2012-12-07 CN CN201210525330.3A patent/CN103873026A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6060952A (en) * | 1998-11-02 | 2000-05-09 | Atsumi Electric Co., Ltd. | Amplifier circuit for infrared sensor |
| US6246282B1 (en) * | 1998-11-05 | 2001-06-12 | Nec Corporation | First stage amplifier circuit |
| US20050258884A1 (en) * | 2004-05-18 | 2005-11-24 | Li-Te Wu | [dc level wandering cancellation circuit] |
| CN2819235Y (en) * | 2005-03-09 | 2006-09-20 | 湖南科技大学 | On-line quality state monitoring system of electromagnetic component |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105763182A (en) * | 2014-12-16 | 2016-07-13 | 华硕电脑股份有限公司 | Signal analysis circuit and signal analysis method |
| CN105763182B (en) * | 2014-12-16 | 2018-12-07 | 华硕电脑股份有限公司 | Signal resolution circuit and signal resolution method |
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Application publication date: 20140618 |