Phase-locked amplifier and resistance determination method of phase-locked amplifier

Abstract

The invention discloses a phase-locked amplifier and a resistance determination method of the phase-locked amplifier. The lock-in amplifier comprises an input signal channel, a multi-stage amplifier and an output signal channel; the multi-stage amplifier comprises a first amplifier, a second amplifier and a third amplifier; the high-pass filter is arranged between the first amplifier and the second amplifier; the third amplifier is arranged between the second amplifier and the output signal channel; the first amplifier is used for converting the obtained current signal to be measured into a voltage signal to be measured and amplifying the voltage signal to obtain a first amplified signal; the high-pass filter carries out filtering processing on the first amplification signal to obtain an AC voltage signal; the second amplifier and the third amplifier sequentially amplify the AC voltage signal to obtain a third amplified signal; and the output signal channel is used for outputting the third amplified signal for signal measurement. According to the phase-locked amplifier, the accuracy of an alternating current signal measurement result in a weak signal can be improved.

Description

Technical Field

[0001] The present application relates to the field of signal measurement technology, and in particular to a lock-in amplifier and a method for determining the resistance of the lock-in amplifier. Background Art

[0002] In the fields of quantum precision measurement, scientific research, and life sciences, it is often necessary to detect weak signals, such as weak photoelectric signals, bioelectric signals, etc. However, these weak signals are often submerged in a strong noise background, and a phase-locked amplifier is required to extract and detect the weak signals to be measured.

[0003] In the prior art, weak test signals and noise are usually input through the input signal channel of a phase-locked amplifier, mixed with a reference signal of the same frequency as the test signal in the mixing module of the phase-locked amplifier, and then output as a measurement result after passing through a filter.

[0004] However, in some application scenarios, such as NV (nitrogen vacancy) color center magnetic measurement, it is necessary to pay attention to the changes or fluctuations of the AC signal in the signal to be measured. However, the signal strength of the AC component is usually much smaller than the signal strength of the DC component. As a result, when using a phase-locked amplifier for signal measurement, the AC signal component in the signal to be measured cannot be accurately measured, resulting in reduced measurement accuracy. Summary of the invention

[0005] Based on the above problems, the present application provides a phase-locked amplifier and a method for determining the resistance of the phase-locked amplifier, the purpose of which is to accurately measure the AC signal component in the signal to be measured and improve the accuracy of the measurement result.

[0006] The embodiments of the present application disclose the following technical solutions:

[0007] In a first aspect, the present application provides a lock-in amplifier, comprising:

[0008] An input signal channel, a multi-stage amplifier and an output signal channel; the multi-stage amplifier includes a first amplifier, a second amplifier and a third amplifier; the high-pass filter is arranged between the first amplifier and the second amplifier; the third amplifier is arranged between the second amplifier and the output signal channel;

[0009] The first amplifier is used to convert the current signal to be measured obtained from the input signal channel into a voltage signal to be measured, and amplify the voltage signal to be measured to obtain a first amplified signal;

[0010] The high-pass filter is used to filter the first amplified signal to obtain an AC voltage signal in the first amplified signal;

[0011] The second amplifier is used to amplify the AC voltage signal to obtain a second amplified signal;

[0012] The third amplifier is used to amplify the second amplified signal to obtain a third amplified signal;

[0013] The output signal channel is used to output the second amplified signal to a detection device, so that the detection device obtains a detection result based on the second amplified signal.

[0014] Optionally, in the lock-in amplifier as described above, the first amplifier comprises a first operational amplifier and a first resistor;

[0015] The inverting input terminal of the first operational amplifier is connected to the input signal channel and one end of the first resistor; the non-inverting input terminal of the first operational amplifier is grounded; and the output terminal of the first operational amplifier is connected to the other end of the first resistor and the input terminal of the high-pass filter.

[0016] Optionally, in the lock-in amplifier as described above, the second amplifier includes a second operational amplifier, a second resistor and a third resistor;

[0017] The non-inverting input terminal of the second operational amplifier is connected to the output terminal of the high-pass filter; the inverting input terminal of the second operational amplifier is connected to one end of the second resistor and one end of the third resistor; the other end of the third resistor is connected to the output terminal of the second operational amplifier; and the other end of the second resistor is grounded.

[0018] Optionally, in the lock-in amplifier as described above, the third amplifier includes a third operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor; the fourth resistor has the same resistance value as the fifth resistor; the sixth resistor has the same resistance value as the seventh resistor;

[0019] The inverting input terminal of the third operational amplifier is connected to one end of the fourth resistor and one end of the sixth resistor; the other end of the fourth resistor is connected to the output terminal of the second operational amplifier; the other end of the sixth resistor is connected to the positive output terminal of the third operational amplifier;

[0020] The non-inverting input terminal of the third operational amplifier is connected to one end of the fifth resistor and one end of the seventh resistor; the other end of the fifth resistor is grounded; and the other end of the seventh resistor is connected to the negative output terminal of the third operational amplifier.

[0021] Optionally, in the phase-locked amplifier as described above, the resistance value of the fourth resistor is the same as that of the fifth resistor; and the resistance value of the sixth resistor is the same as that of the seventh resistor.

[0022] In a second aspect, the present application provides a method for determining resistance of a lock-in amplifier, which is applied to the lock-in amplifier described in any one of the above embodiments, and the method includes:

[0023] Based on the established noise model corresponding to each amplifier in the phase-locked amplifier, the equivalent input noise and equivalent output voltage noise of each amplifier are obtained respectively; the equivalent input noise includes equivalent input voltage source noise and equivalent input current source noise;

[0024] Substituting the gain of each amplifier, the equivalent input noise of each amplifier and the equivalent output voltage noise of each amplifier into a preset total input noise expression of the lock-in amplifier to obtain the total input noise of the lock-in amplifier; the gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the lock-in amplifier is related to the gain of each amplifier and the frequency of the AC signal in the signal to be measured;

[0025] Determining the resistance values ​​of the third resistor, the sixth resistor and the seventh resistor based on the driving capability of the preset digital converter in the lock-in amplifier;

[0026] Based on the total input noise of the lock-in amplifier, respectively draw relationship curves between the total input noise and the gain of each amplifier;

[0027] According to the relationship curve between the total input noise and the gain of each amplifier, the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor are determined respectively.

[0028] Optionally, in the method as described above, determining the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor respectively according to the relationship curve between the total input noise and the gain of each amplifier includes:

[0029] Determining a first gain, a second gain, and a third gain according to a relationship curve between the total input noise and the gain of each amplifier;

[0030] Based on the gain of the first amplifier, determining a first resistor according to the first gain;

[0031] Based on the gain of the second amplifier, determining a second resistor according to the second gain and the resistance value of the third resistor;

[0032] Based on the gain of the third amplifier, the resistance value of the fifth resistor is determined according to the third gain and the resistance value of the sixth resistor.

[0033] In a third aspect, the present application provides a resistance determination device for a lock-in amplifier, comprising:

[0034] A model building module, used for obtaining the equivalent input noise and equivalent output voltage noise of each amplifier based on the established noise model corresponding to each amplifier in the phase-locked amplifier; the equivalent input noise includes equivalent input voltage source noise and equivalent input current source noise;

[0035] A processing module, used for substituting the gain of each amplifier, the equivalent input noise of each amplifier and the equivalent output voltage noise of each amplifier into a preset total input noise expression of the lock-in amplifier to obtain the total input noise of the lock-in amplifier; the gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the lock-in amplifier is related to the gain of each amplifier and the frequency of the AC signal in the signal to be measured;

[0036] A first determination module, configured to determine the resistance values ​​of the third resistor, the sixth resistor, and the seventh resistor based on the driving capability of the preset digital converter in the lock-in amplifier;

[0037] A curve drawing module, used for drawing a relationship curve between the total input noise and the gain of each amplifier based on the total input noise of the lock-in amplifier;

[0038] The second determination module is used to determine the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor respectively according to the relationship curve between the total input noise and the gain of each amplifier.

[0039] In a fourth aspect, the present application provides an electronic device, the device comprising: a processor, and a memory communicatively connected to the processor;

[0040] Memory stores computer-executable instructions;

[0041] The processor executes the computer-executable instructions stored in the memory to implement the resistance determination method of the lock-in amplifier described in any of the above embodiments.

[0042] In a fifth aspect, the present application provides a computer-readable storage medium, in which computer execution instructions are stored. When the computer execution instructions are executed by a processor, they are used to implement the resistance determination method of the phase-locked amplifier described in any of the above embodiments.

[0043] Compared with the prior art, this application has the following beneficial effects:

[0044] The input signal channel of the phase-locked amplifier of the present application obtains the current signal to be measured, and the multi-stage amplifier includes a first amplifier, a second amplifier and a third amplifier, and the high-pass filter is arranged between the first amplifier and the second amplifier, and the third amplifier is arranged between the second amplifier and the output signal channel. Among them, the first amplifier converts the current signal to be measured into a voltage signal to be measured, and amplifies the voltage signal to be measured to obtain a first amplified signal, so as to facilitate subsequent signal measurement; the high-pass filter then filters the amplified first amplified signal, and extracts the AC voltage signal in the first amplified signal from the first amplified signal. Since the intensity of the AC voltage signal is low, the extracted AC voltage signal is further amplified by the second amplifier and the third amplifier to obtain the second amplified signal, and the third amplified signal is output to the detection device in the output signal channel, so that the detection device obtains the detection result based on the third amplified signal. The phase-locked amplifier of the present application can improve the accuracy of measuring the AC signal component in the signal to be measured by amplifying and filtering the signal to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0046] Figure 1 A schematic structural diagram of an embodiment of a lock-in amplifier provided in the present application;

[0047] Figure 2 A schematic structural diagram of another embodiment of a lock-in amplifier provided by the present application;

[0048] Figure 3 A schematic flow chart of an embodiment of a method for determining resistance of a lock-in amplifier provided in the present application;

[0049] Figure 4 A schematic structural diagram of an embodiment of a noise model of a first amplifier provided in the present application;

[0050] Figure 5 A schematic structural diagram of an embodiment of a noise model of a second amplifier provided in the present application;

[0051] Figure 6 A schematic structural diagram of an embodiment of a noise model of a third amplifier provided in the present application;

[0052] Figure 7A schematic structural diagram of an embodiment of a resistance determination device for a lock-in amplifier provided in the present application;

[0053] Figure 8 A schematic structural diagram of an embodiment of an electronic device provided in the present application. DETAILED DESCRIPTION

[0054] As described above, the current phase-locked amplifier is a widely used technical means to detect weak signals. Especially for weak photoelectric signals, the noise intensity usually exceeds the signal intensity, so a phase-locked amplifier is needed to extract and detect the signal to be measured. However, in some specific high-sensitivity measurement scenarios, such as NV color center magnetic measurement, the measurement accuracy of the AC component is usually required to be higher. In actual situations, the signal strength of the AC component is much smaller than the signal strength of the DC component, which makes it difficult for general phase-locked amplifiers to measure the AC component with higher accuracy in this application scenario.

[0055] After research, the inventors proposed a phase-locked amplifier and a method for determining the resistance of the phase-locked amplifier to solve the technical problem of low measurement accuracy of the AC signal component in the measured signal in the prior art.

[0056] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0057] See also Figure 1 , which is a schematic diagram of the structure of an embodiment of a phase-locked amplifier provided by the present application. Figure 1 As shown, the phase-locked amplifier 10 includes an input signal channel 11, a multi-stage amplifier 12, a high-pass filter 13 and an output signal channel 14; the multi-stage amplifier includes a first amplifier 121, a second amplifier 122 and a third amplifier 123; the high-pass filter 13 is arranged between the first amplifier 121 and the second amplifier 122; the third amplifier 123 is arranged between the second amplifier 122 and the output signal channel 14.

[0058] The first amplifier 121 is used to convert the current signal to be measured obtained from the input signal channel 11 into a voltage signal to be measured, and amplify the voltage signal to be measured to obtain a first amplified signal. The high-pass filter 13 is used to filter the first amplified signal to obtain an AC voltage signal in the first amplified signal. The second amplifier 122 is used to amplify the AC voltage signal to obtain a second amplified signal. The third amplifier 123 is used to amplify the second amplified signal to obtain a third amplified signal. The output signal channel 14 is used to output the third amplified signal to the detection device, so that the detection device obtains a detection result based on the third amplified signal.

[0059] In this embodiment, the input signal channel in the phase-locked amplifier obtains the current signal to be measured, the multi-stage amplifier includes a first amplifier, a second amplifier and a third amplifier, and the high-pass filter is arranged between the first amplifier and the second amplifier, and the third amplifier is arranged between the second amplifier and the output signal channel. Among them, the first amplifier converts the current signal to be measured into a voltage signal to be measured, and amplifies the voltage signal to be measured to obtain a first amplified signal, so as to facilitate subsequent signal measurement; the high-pass filter then filters the amplified first amplified signal, extracts the AC voltage signal in the first amplified signal from the first amplified signal, and because the intensity of the AC voltage signal is relatively low, the extracted AC voltage signal is further amplified by the second amplifier and the third amplifier to obtain a second amplified signal, and the third amplified signal is output to the detection device in the output signal channel, so that the detection device obtains the detection result based on the third amplified signal. The phase-locked amplifier of the present application can improve the accuracy of measuring the AC signal component in the signal to be measured by amplifying and filtering the signal to be measured.

[0060] See also Figure 2 , which is a schematic diagram of the structure of another embodiment of a phase-locked amplifier provided by the present application. Figure 2 As shown, the circuit structure of the phase-locked amplifier includes, from left to right, a first amplifier 121, a high-pass filter 13, a second amplifier 122 and a third amplifier 123.

[0061] Specifically, the first amplifier 121 includes a first operational amplifier 1211 and a first resistor R F1 ;

[0062] The inverting input terminal of the first operational amplifier 1211 is connected to the input signal channel and the first resistor R F1 The non-inverting input terminal of the first operational amplifier 1211 is grounded; the output terminal of the first operational amplifier 1211 is connected to the first resistor R F1 and the other end of the high-pass filter 13.

[0063] The second amplifier 122 includes a second operational amplifier 1221, a second resistor R G1 And the third resistor R F2 ;

[0064] The non-inverting input terminal of the second operational amplifier 1221 is connected to the output terminal of the high-pass filter 13; the inverting input terminal of the second operational amplifier 1221 is connected to the second resistor R G1 One end of the third resistor R F2 One end of the third resistor R F2 The other end of the second resistor R G1 The other end is grounded.

[0065] The third amplifier 123 includes a third operational amplifier 1231, a fourth resistor and a fifth resistor R1, and a sixth resistor and a seventh resistor R2. The fourth resistor and the fifth resistor have the same resistance value, so they are both represented by R1; the sixth resistor and the seventh resistor have the same resistance value, so they are both represented by R2.

[0066] The inverting input terminal of the third operational amplifier 1231 is connected to one end of the fourth resistor R1 and one end of the sixth resistor R2; the other end of the fourth resistor R1 is connected to the output terminal of the second operational amplifier 1231; the other end of the sixth resistor R2 is connected to the positive output terminal of the third operational amplifier 1231.

[0067] The non-inverting input terminal of the third operational amplifier 1231 is connected to one end of the fifth resistor R1 and one end of the seventh resistor R2 ; the other end of the fifth resistor R1 is grounded; the other end of the seventh resistor R2 is connected to the negative output terminal of the third operational amplifier 1231 .

[0068] First, it is necessary to determine the range of the input signal to be measured. Under the condition that the analog to digital converter (ADC) of the detection equipment used does not exceed its range, the input signal to be measured is passed through the amplification circuit to achieve the largest possible gain. In one of the magnetic measurement application scenarios involved in the present invention, the input AC current signal is I in μApp.

[0069] Among them, the theoretical maximum gain of the amplifier circuit is Among them, V in is the output AC voltage signal; the equivalent input noise of ADC is Among them, e ADC is the differential voltage of the ADC used.

[0070] See also Figure 3, which is a flow chart of an embodiment of a method for determining resistance of a lock-in amplifier provided by the present application. The method is applied to any of the lock-in amplifiers in the above embodiments, and the method comprises:

[0071] S101: Based on the established noise model corresponding to each amplifier in the phase-locked amplifier, the equivalent input noise and equivalent output voltage noise of each amplifier are obtained respectively.

[0072] The equivalent input noise includes the equivalent input voltage source noise and the equivalent input current source noise.

[0073] In this embodiment, the noise model of the first amplifier is as follows: Figure 4 As shown; among them, Figure 4 The middle blue graph identifies the equivalent voltage source noise of the first amplifier, Figure 4 The red graph in the middle shows the equivalent current source noise, e o1 is the equivalent output voltage noise. The noise model of the second amplifier is as follows Figure 5 As shown; among them, Figure 5 The middle blue graph identifies the equivalent voltage source noise of the second amplifier, Figure 5 The red graph in the middle shows the equivalent current source noise, e o2 is the equivalent output voltage noise. The noise model of the third amplifier is as follows Figure 6 As shown; among them, Figure 6 The middle blue graph identifies the equivalent voltage source noise of the third amplifier, Figure 6 The red graph in the middle shows the equivalent current source noise, e o3 is the equivalent output voltage noise.

[0074] For each amplifier, its noise source mainly consists of two parts, including the thermal noise of the resistor in the amplifier, the equivalent input current source noise and the equivalent input voltage source noise; among them, the thermal noise expression of the resistor can be expressed as

[0075] Where k is the Boltzmann constant, k = 1.38 × 10 -23 J / K; T is Kelvin thermodynamic temperature; R is the resistance value.

[0076] The approximate expression of the equivalent input voltage source noise is: The approximate expression of the equivalent input current source noise is:

[0077] Among them, e n-1Hz ,i n-1Hz is the noise of the current amplifier at 1Hz frequency; e n0 ,i n0is the noise of the current amplifier when it works in the flat band; m and n are constants related to the properties of the current amplifier itself.

[0078] like Figure 4 As shown, the noise model of the first amplifier is analyzed to obtain the equivalent output voltage noise e corresponding to the first amplifier. o1 , equivalent output voltage noise e o1 The expression is as follows:

[0079]

[0080] Among them, R F1 is the resistance value of the first resistor, i n1 The equivalent input current source noise contributed by the first amplifier, C D is the parasitic capacitance of the photodiode of the front-end circuit, T is the operating temperature, e n1 Equivalent input voltage source noise contributed by the first amplifier.

[0081] like Figure 5 As shown, the noise model of the second amplifier is analyzed to obtain the equivalent output voltage noise e corresponding to the second amplifier. o2 , equivalent output voltage noise e o2 The expression is as follows:

[0082]

[0083] Among them, R S2 is the resistance value of the resistor in the high-pass filter, R G2 is the resistance of the second resistor, R F2 is the resistance value of the third resistor. n2 The equivalent input current source noise contributed by the second amplifier, e n2 Equivalent input voltage source noise contributed to the second amplifier.

[0084] like Figure 6 As shown, the noise model of the third amplifier is analyzed to obtain the equivalent output voltage noise e corresponding to the third amplifier. o3 , equivalent output voltage noise e o3 The expression is as follows:

[0085]

[0086] Wherein, R2 is the resistance value of the sixth and seventh resistors; R1 is the resistance value of the fourth and fifth resistors. n3 The equivalent input current source noise contributed by the third amplifier, e n3 Equivalent input voltage source noise contributed by the first amplifier.

[0087] S102: Substituting the gain of each amplifier, the equivalent input noise of each amplifier, and the equivalent output voltage noise of each amplifier into a preset total input noise expression of the lock-in amplifier to obtain the total input noise of the lock-in amplifier.

[0088] The gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the lock-in amplifier is related to the gain of each amplifier and the frequency of the AC signal in the signal to be measured.

[0089] In this embodiment, according to the resistance value R of the first resistor in the first amplifier F1 It can be obtained that the gain of the first amplifier can be expressed as Gain1 = R F1 ;

[0090] According to the resistance value R of the second resistor in the second amplifier G2 And the resistance value of the third resistor R F2 It can be obtained that the expression of the gain of the second amplifier is as follows:

[0091]

[0092] According to the resistance values ​​R1 of the fourth and fifth resistors and the resistance values ​​R2 of the sixth and seventh resistors in the third amplifier, the expression of the gain of the third amplifier can be obtained as follows:

[0093]

[0094] The total input noise of the preset lock-in amplifier corresponds to the expression i n , As shown below:

[0095]

[0096] Then, the gain Gain1 of the first amplifier, the gain Gain2 of the second amplifier, and the gain Gain3 of the third amplifier; the equivalent input noise of the first amplifier e n1 with i n1 , the equivalent input noise of the second amplifier e n2 with i n2 and the equivalent input noise of the third amplifier e n3 with i n3 ; The equivalent output voltage noise of the first amplifier e o1 , the equivalent output voltage noise of the second amplifier e o2 and the equivalent output voltage noise of the third amplifier e o3 , substituting into the preset total input noise expression of the phase-locked amplifier, the total input noise of the phase-locked amplifier is obtained. n .

[0097] It can be understood that, under the condition of ensuring the maximum total gain of the amplifier circuit, the equivalent input noise of the amplifier circuit is a function of the frequency f of the AC component of the signal to be measured, and the gains Gain1, Gain2, and Gain3 of each amplifier. At the same time, since there is an upper limit to the product of the three-stage gain, the equivalent input noise can be regarded as a function of three independent variables, namely, i n =i n (f,Gain1,Gain2).

[0098] S103: Determine the resistance values ​​of the third resistor, the sixth resistor, and the seventh resistor based on the driving capability of the preset digital converter in the lock-in amplifier.

[0099] In this embodiment, the driving capability of the digital converter ADC used in the lock-in amplifier has an upper limit, which limits the lower limit of the resistance value. Therefore, the resistance value R of the third resistor can be determined as F2 , the resistance value of the sixth and seventh resistors is R2.

[0100] S104: Based on the total input noise of the lock-in amplifier, respectively draw relationship curves between the total input noise and the gain of each amplifier.

[0101] In this embodiment, according to the relationship between the equivalent input noise of each amplifier and the corresponding amplifier gain, by scanning the preset appropriate value interval Gain1∈[Gain 1,min ,Gain 1,max ],Gain2∈[Gain 2,min ,Gain 2,max ],Gain3∈

[0102] [Gain 3,min ,Gain 3,max ], and the equivalent input noise i n The relationship curve between the AC component frequency f of the signal to be measured.

[0103] It can be understood that as the gain of the first amplifier increases, the equivalent input noise decreases significantly, and changes in the gains of the second amplifier and the third amplifier do not significantly change the equivalent input noise.

[0104] By controlling the variables, the AC component frequency f of the input signal to be measured and the gains of the two amplifiers are fixed, and the i n -Gain1,i n -Gain2 and i n -Gain3 relationship curve.

[0105] S105: According to the relationship curve between the total input noise and the gain of each amplifier, the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor are determined respectively.

[0106] In this embodiment, in order to ensure that the total gain of the phase-locked amplifier is maximized, the gain Gain1 of the first amplifier, the gain Gain2 of the second amplifier, and the gain Gain3 of the third amplifier are determined according to the relationship curve between the total input noise and the gain of each amplifier; further, based on the relationship expression between the gain of each amplifier and the resistance value, the first resistor R is calculated. F1 , the second resistor R G2 , the resistance value of the fourth resistor and the resistance value of the fifth resistor are R1.

[0107] In this embodiment, based on the noise model corresponding to each amplifier in the established phase-locked amplifier, the equivalent input noise and equivalent output voltage noise of each amplifier are obtained respectively, so that the noise level of the phase-locked amplifier in the entire phase-locked amplifier can be accurately evaluated; the equivalent input noise includes the equivalent input voltage source noise and the equivalent input current source noise; the gain of each amplifier, the equivalent input noise of each amplifier and the equivalent output voltage noise of each amplifier are substituted into the preset total input noise expression of the phase-locked amplifier to obtain the total input noise of the phase-locked amplifier; the gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the phase-locked amplifier is related to the gain of each amplifier and the frequency of the AC signal in the measured signal; based on the driving capability of the preset digital converter in the phase-locked amplifier, the resistance values ​​of the third resistor, the sixth resistor and the seventh resistor are determined; based on the total input noise of the phase-locked amplifier, the relationship curves between the total input noise and the gain of each amplifier are respectively drawn; according to the relationship curves between the total input noise and the gain of each amplifier, the resistance values ​​of the first resistor, the second resistor, the fourth resistor and the fifth resistor are respectively determined, so as to obtain more accurate resistance values, reduce the total input noise in the entire phase-locked amplifier, and improve the accuracy of signal measurement.

[0108] Further, based on the above embodiment, a specific implementation of "determining the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor respectively according to the relationship curve between the total input noise and the gain of each amplifier" in S105 includes:

[0109] According to the relationship curve between the total input noise and the gain of each amplifier, a first gain, a second gain and a third gain are determined.

[0110] Since the noise contributed by the first amplifier is the main source of the total equivalent input noise of the lock-in amplifier, the gain of the first amplifier should be as large as possible, and the gain allocation of the second and third amplifiers has no obvious effect on the total equivalent input noise of the lock-in amplifier. Based on the relationship curve between the total input noise and the gain of each amplifier, the first gain Gain1, the second gain Gain2 and the third gain Gain3 are selected.

[0111] Based on the gain of the first amplifier, a first resistor is determined according to the first gain.

[0112] Since Gain1=R F1 Therefore, based on the determination of the first gain Gain1, the resistance value of the first resistor R can be obtained. F1 .

[0113] Based on the gain of the second amplifier, the second resistor is determined according to the second gain and the resistance value of the third resistor.

[0114] because Therefore, based on the determination of the second gain Gain2 and the resistance value R of the third resistor F2 The resistance value of the second resistor R can be obtained G2 .

[0115] Based on the gain of the third amplifier, the resistance value of the fifth resistor is determined according to the third gain and the resistance value of the sixth resistor.

[0116] because Therefore, the resistance values ​​R1 of the fourth resistor and the fifth resistor can be obtained based on the determined third gain Gain3 and the resistance value R2 of the sixth resistor.

[0117] In this embodiment, the first gain, the second gain and the third gain are determined according to the relationship curve between the total input noise and the gain of each amplifier; the first resistor is determined according to the first gain based on the gain of the first amplifier; the second resistor is determined according to the second gain and the resistance value of the third resistor based on the gain of the second amplifier; the resistance value of the fifth resistor is determined according to the third gain and the resistance value of the sixth resistor based on the gain of the third amplifier, thereby accurately setting the gain and resistance, which helps to reduce the loss and interference of the signal during the transmission process, thereby enhancing the accuracy of signal measurement.

[0118] See also Figure 7 , which is a schematic diagram of the structure of an embodiment of a resistance determination device of a phase-locked amplifier of the present application. Figure 7 As shown, the device 70 includes a model building module 71 , a processing module 72 , a first determination module 73 , a curve drawing module 74 and a second determination module 75 .

[0119] The model building module 71 is used to obtain the equivalent input noise and equivalent output voltage noise of each amplifier based on the noise model corresponding to each amplifier in the established phase-locked amplifier; the equivalent input noise includes the equivalent input voltage source noise and the equivalent input current source noise;

[0120] The processing module 72 is used to substitute the gain of each amplifier, the equivalent input noise of each amplifier and the equivalent output voltage noise of each amplifier into a preset total input noise expression of the phase-locked amplifier to obtain the total input noise of the phase-locked amplifier; the gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the phase-locked amplifier is related to the gain of each amplifier and the frequency of the AC signal in the signal to be measured;

[0121] The first determination module 73 is used to determine the resistance values ​​of the third resistor, the sixth resistor and the seventh resistor based on the driving capability of the preset digital converter in the lock-in amplifier;

[0122] The curve drawing module 74 is used to draw the relationship curve between the total input noise and the gain of each amplifier based on the total input noise of the lock-in amplifier;

[0123] The second determination module 75 is used to determine the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor respectively according to the relationship curve between the total input noise and the gain of each amplifier.

[0124] A resistance determination device for a phase-locked amplifier provided in an embodiment of the present application can execute the technical solution shown in the above method embodiment, and its implementation principle and beneficial effects are similar, which will not be repeated here.

[0125] Further, based on the above embodiment, the second determination module 75 is specifically used to determine the target total input noise corresponding to the preset first gain according to the relationship curve between the total input noise and the gain of the first-stage amplifier; determine the second gain corresponding to the target total input noise according to the relationship curve between the total input noise and the gain of the second-stage amplifier; determine the third gain corresponding to the target total input noise according to the relationship curve between the total input noise and the gain of the third-stage amplifier; and determine the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor based on the first gain, the second gain, and the third gain.

[0126] A resistance determination device for a phase-locked amplifier provided in an embodiment of the present application can execute the technical solution shown in the above method embodiment, and its implementation principle and beneficial effects are similar, which will not be repeated here.

[0127] See also Figure 8 , which is a schematic diagram of the structure of an electronic device according to an embodiment of the present application. The electronic device 80 may include: a processor 81 and a memory 82.

[0128] The processor 81 is in communication connection with the memory 82 , and the memory 82 is used to store computer-executable instructions; the processor 81 is configured to execute the technical solution in any of the aforementioned method embodiments by executing the computer-executable instructions stored in the memory 82 .

[0129] Optionally, the memory 82 may be independent or integrated with the processor 81. Optionally, when the memory 82 is a device independent of the processor 81, the electronic device 80 may further include: a bus for connecting the above devices.

[0130] The electronic device is used to execute the technical solution in any of the aforementioned method embodiments, and its implementation principle and technical effect are similar and will not be repeated here.

[0131] An embodiment of the present application also provides a computer-readable storage medium, which stores computer execution instructions. When the computer execution instructions are executed by a processor, they are used to implement the above-mentioned method. The implementation principle and technical effect are similar and will not be repeated here.

[0132] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device embodiment described above is merely schematic, in which the unit described as a separate component may or may not be physically separated, and the component prompted as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0133] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A lock-in amplifier, characterized in that: include: An input signal channel, a multi-stage amplifier and an output signal channel; the multi-stage amplifier includes a first amplifier, a second amplifier and a third amplifier; The high-pass filter is arranged between the first amplifier and the second amplifier; the third amplifier is arranged between the second amplifier and the output signal channel; The first amplifier is used to convert the current signal to be measured obtained from the input signal channel into a voltage signal to be measured, and amplify the voltage signal to be measured to obtain a first amplified signal; The high-pass filter is used to filter the first amplified signal to obtain an AC voltage signal in the first amplified signal; The second amplifier is used to amplify the AC voltage signal to obtain a second amplified signal; The third amplifier is used to amplify the second amplified signal to obtain a third amplified signal; The output signal channel is used to output the third amplified signal to a detection device, so that the detection device obtains a detection result based on the second amplified signal.

2. The lock-in amplifier according to claim 1, characterized in that: The first amplifier includes a first operational amplifier and a first resistor; The inverting input terminal of the first operational amplifier is connected to the input signal channel and one end of the first resistor; the non-inverting input terminal of the first operational amplifier is grounded; and the output terminal of the first operational amplifier is connected to the other end of the first resistor and the input terminal of the high-pass filter.

3. The lock-in amplifier according to claim 1, characterized in that: The second amplifier includes a second operational amplifier, a second resistor and a third resistor; The non-inverting input terminal of the second operational amplifier is connected to the output terminal of the high-pass filter; the inverting input terminal of the second operational amplifier is connected to one end of the second resistor and one end of the third resistor; the other end of the third resistor is connected to the output terminal of the second operational amplifier; and the other end of the second resistor is grounded.

4. The lock-in amplifier according to claim 1, characterized in that: The third amplifier includes a third operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor; The inverting input terminal of the third operational amplifier is connected to one end of the fourth resistor and one end of the sixth resistor; the other end of the fourth resistor is connected to the output terminal of the second operational amplifier; the other end of the sixth resistor is connected to the positive output terminal of the third operational amplifier; The non-inverting input terminal of the third operational amplifier is connected to one end of the fifth resistor and one end of the seventh resistor; the other end of the fifth resistor is grounded; and the other end of the seventh resistor is connected to the negative output terminal of the third operational amplifier.

5. The lock-in amplifier according to claim 4, characterized in that: The fourth resistor has the same resistance value as the fifth resistor; the sixth resistor has the same resistance value as the seventh resistor.

6. A method for determining the resistance of a lock-in amplifier, characterized in that: The lock-in amplifier according to any one of claims 1 to 5, comprising: Based on the established noise model corresponding to each amplifier in the phase-locked amplifier, the equivalent input noise and equivalent output voltage noise of each amplifier are obtained respectively; the equivalent input noise includes equivalent input voltage source noise and equivalent input current source noise; Substituting the gain of each amplifier, the equivalent input noise of each amplifier and the equivalent output voltage noise of each amplifier into a preset total input noise expression of the lock-in amplifier to obtain the total input noise of the lock-in amplifier; the gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the lock-in amplifier is related to the gain of each amplifier and the frequency of the AC signal in the signal to be measured; Determining the resistance values ​​of the third resistor, the sixth resistor and the seventh resistor based on the driving capability of the preset digital converter in the lock-in amplifier; Based on the total input noise of the lock-in amplifier, respectively draw relationship curves between the total input noise and the gain of each amplifier; According to the relationship curve between the total input noise and the gain of each amplifier, the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor are determined respectively.

7. The method according to claim 6, characterized in that The step of determining the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor respectively according to the relationship curve between the total input noise and the gain of each amplifier comprises: Determining a first gain, a second gain, and a third gain according to a relationship curve between the total input noise and the gain of each amplifier; Based on the gain of the first amplifier, determining a first resistor according to the first gain; Based on the gain of the second amplifier, determining a second resistor according to the second gain and the resistance value of the third resistor; Based on the gain of the third amplifier, the resistance value of the fifth resistor is determined according to the third gain and the resistance value of the sixth resistor.

8. A resistance determination device for a lock-in amplifier, characterized in that: include: A model building module, used for obtaining the equivalent input noise and equivalent output voltage noise of each amplifier in the phase-locked amplifier based on the established noise model corresponding to each amplifier; The equivalent input noise includes equivalent input voltage source noise and equivalent input current source noise; A processing module, used for substituting the gain of each amplifier, the equivalent input noise of each amplifier and the equivalent output voltage noise of each amplifier into a preset total input noise expression of the lock-in amplifier to obtain the total input noise of the lock-in amplifier; the gain of the amplifier is determined according to the resistance value of the resistor in the amplifier; the total input noise of the lock-in amplifier is related to the gain of each amplifier and the frequency of the AC signal in the signal to be measured; A first determination module, configured to determine the resistance values ​​of the third resistor, the sixth resistor, and the seventh resistor based on the driving capability of the preset digital converter in the lock-in amplifier; A curve drawing module, used for drawing a relationship curve between the total input noise and the gain of each amplifier based on the total input noise of the lock-in amplifier; The second determination module is used to determine the resistance values ​​of the first resistor, the second resistor, the fourth resistor, and the fifth resistor respectively according to the relationship curve between the total input noise and the gain of each amplifier.

9. An electronic device, characterized in that: The device comprises: a processor, and a memory communicatively connected to the processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory to implement the method according to any one of claims 6 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 6 to 7 when executed by a processor.

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