CN104635050A - Impedance detection device and method - Google Patents
Impedance detection device and method Download PDFInfo
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- CN104635050A CN104635050A CN201310555107.8A CN201310555107A CN104635050A CN 104635050 A CN104635050 A CN 104635050A CN 201310555107 A CN201310555107 A CN 201310555107A CN 104635050 A CN104635050 A CN 104635050A
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Abstract
Disclosed are an impedance detection device and method which can detect the impedance of a load. In an embodiment, the impedance detection device comprises an alternating-current signal generation circuit, an output buffer, a current mirror, a detection impedor, a clock pulse generation circuit, a comparison circuit and a control circuit; the alternating-current signal generation circuit is used for providing an alternating-current signal; the output buffer is used for generating output voltage and output current according to the alternating-current signal and the impedance of the load; the current mirror is used for generating image current according to the output current; the detection impedor is used for generating detection voltage according to the image current; the clock pulse generation circuit is used for providing a clock pulse; the comparison circuit is used for comparing the output voltage with the detection voltage according to the clock pulse so as to generate a comparison result; the control circuit is coupled to the comparison circuit and at least one of the current mirror and the detection impedor and used for regulating at least one of the proportion between the image current and the output current and the impedance of the detection impedor according to the comparison result till the comparison result meets a preset condition. By the impedance detection device and method, abnormal sound can be avoided.
Description
Technical field
The present invention relates to pick-up unit and method, particularly relate to impedance detection apparatus and method.
Background technology
Many existing consumer electronic devices all can provide one or more audio output hole, with one or more voice output external, and such as all types of earphones and loudspeaker etc.But the voice output of different size can produce different output effects for identical voice signal, it is moderate that also namely same voice signal exports possibility volume via loudspeaker, but export then deafening via earphone; Or melodious fitting is listened when same voice signal is exported by the earphone of a certain type, but constrain distortion when being exported by the earphone of another type.The problems referred to above mainly because the output impedance (or saying the input impedance of voice output) desired by audio codec (Audio Codec) of output sound signal and actual state are not inconsistent, thus output the voice signal that amplitude is excessive or too small.And in order to adapt to the larger voice output of input impedance (such as active loudspeaker etc., now audio codec meeting is in the face of larger output impedance) with the signal providing volume larger, and adapt to input impedance little voice output (such as passive type loudspeaker or earphone etc., now audio codec meeting is in the face of less output impedance) with the signal providing volume less, current technology be audio codec output buffer (Output Buffer) 110 with connect a resistance 130(between external voice output 120 as shown in Figure 1), to be adjusted the output to the signal energy of voice output 120 by the dividing potential drop effect of this resistance 130, but, this kind of solution comprises at least its own shortcomings: one, if voice output 120 has electric capacity or inductive effect, even if output buffer 110 is not with the amplitude of frequency adjustment output signal, different impedance effect can be presented with frequency change based on electric capacity or inductive effect, the situation that the low-and high-frequency volume that still there will be the audio of voice output 120 differs, what is more, because the voice output of different size may have different electric capacity or inductive effect, therefore deviser is also difficult to carry out accommodation all sidedly, they are two years old, on usual circuit board, audio codec is very long to the path of audio output hole, easily by noise, when not arranging resistance 130, output buffer 110 still reduces noise coupling effect by low-down output impedance, but when arranging resistance 130, therefore the anti-noise ability of output buffer 110 can detract on the contrary, its three, usual resistance 130 is passive elements circuit board with fixed resistance value, but the specification of voice output 120 is a lot of, and deviser is difficult to use the resistance 130 of fixed resistance value to mate all voice outputs, therefore can produce the problem of attending to one thing and lose sight of another.
Other prior art can the U.S. patent application case of referenced patent publication number 20130158921.
Summary of the invention
In view of the defect of prior art, the object of the present invention is to provide impedance detection apparatus and method, to solve the problem of prior art.
The invention discloses a kind of impedance detection device, the resistance value of a load can be detected.According to one embodiment of the invention, this device comprises: an AC signal generating circuit, is used to provide an AC signal; One output buffer, couples this AC signal generating circuit, is used for electric connection one load, and is used for producing an output voltage and an output current according to the resistance value of this AC signal and this load; One current mirror, couples this output buffer, is used for producing an image current according to this output current; One detects impedance, couples this current mirror, is used for producing one according to this image current and detects voltage; One clock pulse generating circuit, is used to provide a time clock; One comparator circuit, couples this output buffer and this detection impedance, is used for comparing this output voltage and this detection voltage to produce a comparative result according to this time clock; And a control circuit, couple this comparator circuit and this current mirror and this detection impedance at least one of them, be used for according to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned.In the present embodiment, the frequency of this AC signal is less than a first frequency or is greater than a second frequency, and it is poor to there is a preset phase between this AC signal and this time clock.
Invention also discloses a kind of impedance detection method, the resistance value of a load can be detected.According to one embodiment of the invention, the method can perform at least the following step: provide an AC signal; Resistance value according to this AC signal and a load produces an output voltage and an output current; An image current is produced according to this output current; Resistance value and this image current generation one detection voltage of impedance is detected according to one; One time clock is provided; This output voltage and this detection voltage is compared to produce a comparative result according to this time clock; And according to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned.In the present embodiment, the frequency of this AC signal is less than a first frequency or is greater than a second frequency, and it is poor to there is a preset phase between this AC signal and this time clock.
Beneficial effect of the present invention is, in sum, impedance detection apparatus and method of the present invention comprise at least following advantages: one, by detecting the impedance of a load to do adaptive adjustment, thus avoids the problem of prior art; Its two, carry out impedance detection by AC signal, the circuit design with coupling capacitance can be applied to; Its three, by frequency and/or the waveform of limiting AC signal, different sound can be avoided; Its four, by adjustment electric current and impedance accelerate the detection of impedance and/or expand the scope of impedance detection.
Feature for the present invention, practice and effect, hereby coordinate accompanying drawing to be described in detail as follows do preferred embodiment.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of the audio frequency output framework of prior art;
Fig. 2 is the schematic diagram of an embodiment of impedance detection device of the present invention;
Fig. 3 is the schematic diagram of the signal relation of Fig. 2;
Fig. 4 is the schematic diagram of an embodiment of the output buffer of Fig. 2;
Fig. 5 is the process flow diagram of an embodiment of impedance detection method of the present invention; And
Fig. 6 is the process flow diagram of another embodiment of impedance detection method of the present invention.
Wherein, description of reference numerals is as follows:
110 output buffers
120 voice outputs
130 resistance
200 impedance detection devices
210 AC signal generating circuits
220 output buffers
222 buffer amplifiers
224 P-type crystal pipes
226 N-type transistor
228 coupling capacitances
230 loads
240 current mirrors
250 detect impedance
260 clock pulse generating circuits
270 comparator circuits
280 control circuits
S510 provides an AC signal
S520 produces an output voltage and an output current according to the resistance value of this AC signal and a load
S530 produces an image current according to this output current
S540 produces one according to a detection resistance value for impedance and the current value of this image current and detects voltage
S550 provides a time clock
S560 compares this output voltage and this detection voltage to produce a comparative result according to this time clock
S570 according to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned
S580 in this comparative result meet this pre-conditioned after, obtain the resistance value of this load according to this output voltage, this image current and the ratio of this output current and the resistance value of this impedance
S590 according to this load resistance value adjustment one first yield value and one second yield value at least one of them
Embodiment
The technical terms of following description is the idiom with reference to the art, and as this instructions is illustrated part term or defines, the explanation of this part term is as the criterion with the explanation of this instructions or definition.
Disclosure of the present invention comprises impedance detection apparatus and method, is used for the impedance of detection one load.This device and method can be applicable to an integrated circuit (such as audio codec (Audio Codec)) or a system and device (audio output device such as such as computing machine, mobile phone, music player), be embodied as under possible prerequisite, those skilled in the art can select the element of equivalence or step to realize the present invention according to the disclosure of the specification, are also the embodiment chatted after enforcement of the present invention is not limited to.The subelement comprised due to impedance detection device of the present invention may be separately well known elements, therefore under the prerequisite not affecting the fully open of this device invention and exploitativeness, below illustrates that the details for well known elements will be omitted.In addition, impedance detection method of the present invention performs by impedance detection device of the present invention or its equivalent device, under the prerequisite not affecting the fully open of the method invention and exploitativeness, the explanation of following methods invention will focus on step content and non-hardware.
Refer to Fig. 2, it is the schematic diagram of an embodiment of impedance detection device of the present invention, and this embodiment can detect resistance value the using or other utilization for output gain correction of a load.As shown in Figure 2, the impedance detection device 200 of the present embodiment comprises: an AC signal generating circuit 210, be used to provide an AC signal, this AC signal is such as one sinusoidal wave, but the AC signal of other type (such as average amplitude value is the string ripple signal, triangular signal, square-wave signal etc. of zero (also namely flip-flop is zero)) also must be adopted by the present invention being embodied as under possible prerequisite, one output buffer (Output Buffer) 220, couples this AC signal generating circuit 210, is used for electric connection one load 230, and is used for producing an output voltage and an output current according to the resistance value of this AC signal and this load 230, one current mirror 240, couple this output buffer 220, be used for producing an image current according to this output current, described image current is K times of this output current, and wherein K is on the occasion of (such as mark or integer), in the present embodiment, K value adjustable, and variation repeatedly can be done along with testing process, mobility scale is then depending on the demand of implementing present inventor and the element characteristic adopted and circuit framework, if but K value is without necessity of adjustment, also can be a fixed value, one detects impedance 250, couples this current mirror 240, and be used for producing one according to this image current and detect voltage, in the present embodiment, the resistance value of this detection impedance 250 is adjustable, one clock pulse generating circuit 260, be used to provide a time clock, the frequency of this time clock can be equal to the frequency of this AC signal or its M doubly or 1/N doubly, wherein M, N are positive integer, in the present embodiment, this clock pulse generating circuit 260 can be integrated in this AC signal generating circuit 210, and so the two also can separate, one comparator circuit 270, couple this output buffer 220 and this detection impedance 250, be used for comparing this output voltage and this detection voltage to produce a comparative result according to this time clock, described comparator circuit 270 can comprise a unit comparer (such as an operational amplifier) or a multidigit comparer (such as an analog to digital converter (Analog-to-digital Convertor, ADC)) depending on demand, and a control circuit 280, couple this comparator circuit 270 and this current mirror 240 with detect impedance 250 at least one of them, be used for according to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned, in the present embodiment, this control circuit 280 is by micro-control unit, the combination of comparer and logical circuit, the combination in any of lut circuits or more circuit realizes, this is pre-conditioned, and this output voltage and the difference of detection voltage are with being less than a threshold value or this difference continuity at the upper down conversion etc. of a reference value.
Please continue to refer to Fig. 2, in the present embodiment, this AC signal generating circuit 210 is a digital to analog converter (Digital-to-Analog Convertor, DAC), couple this control circuit 280, be used for starting according to the control of this control circuit 280 or stop to produce this AC signal.Because this AC signal generating circuit 210 is realized by DAC, therefore can accurately produce required AC signal, other known signal generator also must be adopted by the present invention when being embodied as possible certainly.In addition, during carrying out impedance detection, this control circuit 280 controls this AC signal generating circuit 210 and produces this AC signal to carry out the detection continuing or be interrupted; Until aforementioned comparative result meet this pre-conditioned after, this control circuit 280 controls this AC signal generating circuit 210 again to be stopped producing this AC signal, recovers a normal operation (such as producing the running of an analogy sound signal according to a source sound signal) to make it.In addition, because aforementioned output voltage and detection voltage all produce according to this AC signal, therefore both are periodically variable voltage, and in order to allow comparator circuit 270 can compare the peak value of this two voltage to obtain relatively correct comparative result, this AC signal and time clock can be poor via designing existence one preset phase in advance, comparator circuit 270 can be compared this output voltage and the peak value detecting voltage along with the triggering of the rising edge of this time clock and/or negative edge, for example, refer to Fig. 3, if this AC signal is identical with the frequency of this time clock, this preset phase difference can be 1/4th or 3/4ths of the cycle of this AC signal, make this output voltage of justified margin of this time clock and the peak value detecting voltage by this, and the magnitude of voltage making comparator circuit 270 compare is the peak value of this two voltage just, and then produce a relatively reliable comparative result.Moreover, if impedance detection device 200 of the present invention is applied to an audio codec, for the different sound avoiding user to hear this AC signal, the present embodiment makes the frequency of this AC signal be less than a first frequency or be greater than a second frequency, wherein this first and second frequency can be lower-frequency limit and the upper limit of people's ear hearing, such as this first frequency is 20Hz, this second frequency is 20KHz, although different people has the different hearing limit, the difference of first and second frequency described is at least greater than 10KHz in the present embodiment.
Refer to Fig. 4, it is the schematic diagram of an embodiment of the output buffer 220 of Fig. 2.As shown in Figure 4, output buffer 220 comprises: a buffer amplifier 222(Buffer Amplifier); One P-type crystal pipe 224; One N-type transistor 226; And a coupling capacitance 228.The source electrode of described P type and N-type transistor 224,226 is coupled to one first bias voltage VDD and one second bias voltage VEE respectively, and this P type and N-type transistor 224,226 are used for providing this output voltage in the positive half period of this AC signal and negative half-cycle respectively.The current mirror 240 of Fig. 2 can be coupled to this two-transistor 224,226 any one to produce this image current, when this current mirror 240 couples this P-type crystal pipe 224 to produce this image current, aforementioned preset phase difference is 1/4th of the cycle of this AC signal, and now this comparator circuit 270 can compare this output voltage and the crest detecting voltage according to the rising edge of this time clock (if this phase of ac signal this time clock leading) or negative edge (if this phase of ac signal falls behind this time clock); Again when this current mirror 240 couples this N-type transistor 226 to produce this image current, this preset phase difference is 3/4ths of the cycle of this AC signal, and now this comparator circuit 270 can compare this output voltage and the trough detecting voltage according to the rising edge of this time clock (if this phase of ac signal this time clock leading) or negative edge (if this phase of ac signal falls behind this time clock).Please note, via suitable design, comparator circuit 270 also can compare according to the rising edge of this time clock and negative edge, and owing to how to operate by the triggering of clock edge the usual knowledge belonging to the art, therefore non-essential explanation will be omitted at this.Separately note that the design of some output buffer does not comprise the coupling capacitance of Fig. 4, but utilize AC signal to carry out impedance detection due to the present invention, therefore no matter with or without this coupling capacitance, all do not affect enforcement of the present invention.Though note that the embodiment of Fig. 2 and Fig. 4 is for the output buffer of double-width grinding/Single-end output again, but be embodied as under possible prerequisite, those skilled in the art can select the known impact damper of other type depending on demand and design specifications.
Please again consult Fig. 2, when the enforcement of this comparator circuit 270 comprises a multidigit comparer (such as an ADC), this comparator circuit 270 can produce an output voltage multibit signal and according to this output voltage and this detection voltage respectively and detect voltage multibit signal, and by comparing this two multibit signal to produce this comparative result.Separately refer to Fig. 2 and Fig. 3, this control circuit 280 can according to this comparative result and a preset rules adjust the ratio (mirror ratio) of this image current and this output current and the resistance value of this detection impedance 250 at least one of them, until this comparative result meets aforementioned pre-conditioned, in more detail, if this control circuit 280 only can adjust this mirror ratio, this detection impedance 250 can be a blocked impedance but not an adjustable impedance; If this control circuit 280 only can adjust this detection resistance value, this mirror ratio can be a fixed proportion (also namely this current mirror 240 is nonadjustable); If this control circuit 280 can adjust this mirror ratio and this detection impedance according to aforementioned preset rules simultaneously or successively, this current mirror 240 with detect impedance 250 and namely need to be conditioned circuit as aforementioned explanation, wherein this preset rules can be the custom rule of the rule that preferentially adjusts of rule, an electric current or impedance that a rule, determined according to current mirror 240 and the Adjustment precision detecting impedance 250 adjusts in turn or this area personage.
From the above, comparative result meet this pre-conditioned after, control circuit 280 just can obtain the resistance value of aforementioned load 230 according to known output voltage (AC signal derived from controlled), this image current and the ratio of this output current and the resistance value of this detection impedance 250, and at least one of them the gain set-point of this AC signal generating circuit 210 and this output buffer 220 can be adjusted according to the resistance value of this load 230, the energy of output signal is adjusted by this adaptively according to the impedance of this load 230.For example, if impedance detection device 200 of the present invention is audio codecs, this load 230 represents the impedance of external voice output, pass through the present invention, no matter which kind of voice output this audio codec connects, control circuit 280 all can estimate the resistance value of this load 230 according to impedance detection result, and then adjust the gain set-point of AC signal generating circuit 210 and/or output buffer 220 accordingly, give this voice output to export suitable sound signal, reach applicable voice output effect.
Except said apparatus invention, the present invention also proposes a kind of impedance detection method, can detect the resistance value of a load.As shown in Figure 5, an embodiment of the method comprises the following step:
Step S510 a: AC signal is provided.This step performs by the AC signal generating circuit 210 of Fig. 2 or its equivalent electrical circuit;
Step S520: the resistance value according to this AC signal and a load produces an output voltage and an output current.This step performs by the output buffer 220 of Fig. 2 or its equivalent electrical circuit;
Step S530: produce an image current according to this output current.This step performs by the current mirror 240 of Fig. 2 or its equivalent electrical circuit;
Step S540: produce one according to a detection resistance value for impedance and the current value of this image current and detect voltage.This step realizes by the detection impedance 250 of Fig. 2;
Step S550 a: time clock is provided.This step performs by the clock pulse generating circuit 260 of Fig. 2 or its equivalent electrical circuit;
Step S560: compare this output voltage and this detection voltage to produce a comparative result according to this time clock.This step performs by the comparator circuit 270 of Fig. 2 or its equivalent electrical circuit; And
Step S570: according to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned.This step performs by the control circuit 280 of Fig. 2 or its equivalent electrical circuit.
From the above, in the present embodiment, a preset phase is there is poor between this AC signal and this time clock, step S560 is enable to compare the peak value of this output voltage and this detection voltage by this, to produce comparative result relatively reliably, for example, if this AC signal is identical with the frequency of this time clock, this preset phase difference can be 1/4th or 3/4ths of the cycle of this AC signal.In addition, for avoid this AC signal cause people's ear can and different sound, the frequency that step S510 can limit this AC signal is less than a first frequency (such as 20Hz) or is greater than a second frequency (such as 20KHz), and wherein the difference of this first and second frequency is greater than 10KHz.In addition, when step S560 be via a multidigit comparer to realize time, step S560 can comprise further: produce an output voltage multibit signal according to this output voltage; Produce one according to this detection voltage and detect voltage multibit signal; And compare this output voltage multibit signal and this detection voltage multibit signal to produce this comparative result.Moreover as shown in Figure 6, after completing abovementioned steps S510 to S570, the present embodiment can comprise the following step further:
Step S580: in this comparative result meet this pre-conditioned after, obtain the resistance value of this load according to this output voltage, this image current and the ratio of this output current and the resistance value of this impedance; And
Step S590: according to this load resistance value adjustment one first yield value and one second yield value at least one of them, wherein this first and second yield value is such as the gain set-point of above-mentioned AC signal generating circuit 210 and the gain set-point of output buffer 220 respectively.
Finally, if the present embodiment is applied to an audio codec or similar device, step S510 and step S520 can comprise: in this comparative result meet this pre-conditioned before, this AC signal is provided and produces this output voltage; And in this comparative result meet this pre-conditioned after, a sound signal is produced according to an audio data and one first yield value, and produce an audio signal voltage according to this sound signal and one second yield value, the step wherein producing sound signal can be performed by the AC signal generating circuit 210 of Fig. 2, now this first yield value refers to the gain set-point of this AC signal generating circuit 210, the step producing audio signal voltage then can be performed by the output buffer 220 of Fig. 2, and now this second yield value refers to the gain set-point of this output buffer 220.
Because those skilled in the art understand this method working of an invention details and change by the relevant disclosure of Fig. 2 to Fig. 5, therefore, under the prerequisite not affecting the method disclosure of an invention requirement and exploitativeness, the explanation of repetition and redundancy will be omitted.Take off before note that in accompanying drawing, the order etc. of the shape of element, size, ratio and step is only signal, is understand the present invention for those skilled in the art, is not used to limit the present invention.In addition, the art personage Ke Yi disclosure of the present invention and the demand of self optionally implement the part or all of technical characteristic of any embodiment, or optionally implement the combination of the part or all of technical characteristic of multiple embodiment, increase elasticity during the invention process by this.
In sum, impedance detection apparatus and method of the present invention comprise at least following advantages: one, by detecting the impedance of a load to do adaptive adjustment, thus avoid the problem of prior art; Its two, carry out impedance detection by AC signal, the circuit design with coupling capacitance can be applied to; Its three, by frequency and/or the waveform of limiting AC signal, different sound can be avoided; Its four, by adjustment electric current and impedance accelerate the detection of impedance and/or expand the scope of impedance detection.
Although embodiments of the invention are described above; but those embodiments are not used for limiting the present invention; those skilled in the art can impose change according to the content expressed or imply of the present invention to technical characteristic of the present invention; all this kind changes the patent protection category that all may belong to sought by the present invention; in other words, scope of patent protection of the present invention must be as the criterion depending on the claim person of defining of this instructions.
Claims (20)
1. an impedance detection device, can detect the resistance value of a load, comprise:
One AC signal generating circuit, is used to provide an AC signal;
One output buffer, couples this AC signal generating circuit, is used for being electrically connected this load, and is used for producing an output voltage and an output current according to the resistance value of this AC signal and this load;
One current mirror, couples this output buffer, is used for producing an image current according to this output current;
One detects impedance, couples this current mirror, is used for producing one according to this image current and detects voltage;
One clock pulse generating circuit, is used to provide a time clock;
One comparator circuit, couples this output buffer, this detection impedance and this clock pulse generating circuit, is used for comparing this output voltage and this detection voltage to produce a comparative result according to this time clock; And
One control circuit, couple this comparator circuit and this current mirror and this detection impedance at least one of them, be used for according to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned.
2. impedance detection device as claimed in claim 1, wherein this AC signal generating circuit is a digital to analog converter, couples this control circuit, is used for starting according to the control of this control circuit or stop to produce this AC signal.
3., wherein there is a preset phase poor in impedance detection device as claimed in claim 1 between this AC signal and this time clock.
4. impedance detection device as claimed in claim 3, wherein this preset phase difference is 1/4th or 3/4ths of the cycle of this AC signal.
5. impedance detection device as claimed in claim 4, wherein this output buffer comprises a P-type crystal Guan Yuyi N-type transistor, be used for respectively producing this output voltage in the positive half period of this AC signal and negative half-cycle, when this current mirror couples this P-type crystal pipe to produce this image current, this phase differential is 1/4th of the cycle of this AC signal, and when this current mirror couples this N-type transistor to produce this image current, this phase differential is 3/4ths of the cycle of this AC signal.
6. impedance detection device as claimed in claim 1, wherein the frequency of this AC signal is less than a first frequency or is greater than a second frequency, and the difference of this first and second frequency is greater than 10KHz.
7. impedance detection device as claimed in claim 6, wherein this first frequency is 20Hz, and this second frequency is 20KHz.
8. impedance detection device as claimed in claim 1, wherein this AC signal is a string ripple.
9. impedance detection device as claimed in claim 1, wherein this comparator circuit is used for producing an output voltage multibit signal and according to this output voltage and this detection voltage respectively and detects voltage multibit signal, and by comparing this output voltage multibit signal and this detection voltage multibit signal to produce this comparative result.
10. impedance detection device as claimed in claim 1, wherein this control circuit be used for according to this comparative result and a preset rules adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned.
11. impedance detection devices as claimed in claim 1, wherein in this comparative result meet this pre-conditioned after, this control circuit is used for obtaining according to the ratio of this output voltage, this image current and this output current and the resistance value of this detection impedance the resistance value of this load, and adjusts at least one of them the gain set-point of this AC signal generating circuit and this output buffer according to the resistance value of this load.
12. impedance detection devices as claimed in claim 1, it is an audio codec, wherein this AC signal generating circuit in this comparative result meet this pre-conditioned before export this AC signal, and meet this pre-conditioned rear foundation one sound signal of originating in this comparative result and export an analogy sound signal.
13. 1 kinds of impedance detection methods, can detect the resistance value of a load, and can perform at least the following step:
One AC signal is provided;
Resistance value according to this AC signal and this load produces an output voltage and an output current;
An image current is produced according to this output current;
Produce one according to a detection resistance value for impedance and the current value of this image current and detect voltage;
One time clock is provided;
This output voltage and this detection voltage is compared to produce a comparative result according to this time clock; And
According to this comparative result adjust the ratio of this image current and this output current and the resistance value of this detection impedance at least one of them, until this comparative result meets one pre-conditioned.
, wherein there is a preset phase between this AC signal and this time clock poor in 14. impedance detection methods as claimed in claim 13.
15. impedance detection methods as claimed in claim 14, wherein this AC signal is a string ripple, and this preset phase difference is 1/4th or 3/4ths of the cycle of this AC signal.
16. impedance detection methods as claimed in claim 13, wherein the frequency of this AC signal is less than a first frequency or is greater than a second frequency, and the difference of this first and second frequency is greater than 10KHz.
17. impedance detection methods as claimed in claim 16, wherein this first frequency is 20Hz, and this second frequency is 20KHz.
18. impedance detection methods as claimed in claim 13, the step wherein producing this comparative result comprises:
An output voltage multibit signal is produced according to this output voltage;
Produce one according to this detection voltage and detect voltage multibit signal; And
Relatively this output voltage multibit signal and this detection voltage multibit signal are to produce this comparative result.
19. impedance detection methods as claimed in claim 13, the step wherein providing this AC signal and produce this output voltage comprises:
In this comparative result meet this pre-conditioned before, this AC signal is provided and produces this output voltage; And
In this comparative result meet this pre-conditioned after, produce a sound signal according to an audio data and one first yield value, and produce an audio signal voltage according to this sound signal and one second yield value.
20. impedance detection methods as claimed in claim 19, comprise the following step further:
In this comparative result meet this pre-conditioned after, obtain the resistance value of this load according to this output voltage, this image current and the ratio of this output current and the resistance value of this impedance; And
Resistance value according to this load adjust this first and second yield value at least one of them.
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| CN105828249A (en) * | 2015-07-01 | 2016-08-03 | 维沃移动通信有限公司 | Electronic device, audio processing circuit thereof, and output method of audio signal |
| CN109089190A (en) * | 2018-10-26 | 2018-12-25 | Oppo广东移动通信有限公司 | Impedance curve determines method, apparatus, storage medium and terminal device |
| CN110082279A (en) * | 2019-05-29 | 2019-08-02 | 青岛理工大学 | A method of measurement ion penetration resistance of concrete numerical value |
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