Universal noise measurement circuit and equipment

Abstract

The present invention discloses a universal noise measurement circuit and device, which includes: a multi-stage filtering and amplifying module, which is used to filter and amplify the noise signal to be measured for multiple times, and simultaneously generate at least two channels of signals to be measured with different cutoff frequencies; a bandwidth buffer module and a low-pass filtering module, which are respectively used to provide a noise measurement channel with noise greater than a third cutoff frequency based on the first channel of the signal to be measured in at least two channels, and provide multiple noise measurement channels with noise greater than the third cutoff frequency and less than different cutoff frequencies of multiple low-pass filtering units; a band-pass filtering module, which is used to provide a noise measurement channel with noise greater than a fourth cutoff frequency and less than the third cutoff frequency based on the second channel of the signal to be measured in at least two channels; and a power supply module, which is used to provide a power supply voltage. The present invention can meet the filtering and amplification of all noise parameters based on one circuit, and can thus simultaneously realize noise measurement of different chips and circuits, and has strong versatility.

Description

Technical Field

[0001] The present invention relates to the technical field of noise measurement, and in particular to a universal noise measurement circuit and equipment. Background Art

[0002] In various activities of engineering technology, scientific research and production practice, nV AC voltage signal detection is widely used in oil well logging, optical analysis, superconducting material evaluation, metal material tension test, Auger electron spectroscopy, metal detection, eddy current flaw detection, electron beam measurement and other fields. Since the background noise in these fields is very strong and the measured signal is very weak, it is very difficult to detect effective signals from them. Researching nV AC voltage signal detection, exploring new detection methods, and developing new detection equipment are currently a hot spot and difficulty in the field of weak signal detection technology.

[0003] For nV level signals, due to various noises introduced by the measurement system and external interference, the noise is dozens of times higher than the useful signal. Some traditional voltage measurement methods are powerless to measure nV level voltages submerged in strong noise. In noise measurement, for operational amplifiers, LDO (Low Dropout Regulator) and REF chips, the measurement system is not unified. The noise measurement of some chips or circuits even requires multiple different auxiliary systems to assist, which makes classification and storage more troublesome. At the same time, for some measurement circuits, the large capacitor of the input high-pass circuit charges slowly, affecting the measurement efficiency and accuracy.

[0004] Therefore, it is necessary to provide an improved technical solution to overcome the above technical problems existing in the prior art. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a universal noise measurement circuit and device, which can meet the filtering and amplification of all noise parameters based on one circuit, and can thus simultaneously realize noise measurement of different chips and circuits, with strong versatility.

[0006] According to a universal noise measurement circuit provided by the present invention, the circuit comprises: a first filtering and amplifying module, receiving a noise signal to be measured, and performing a first-stage filtering and amplifying on the noise signal to be measured; a second filtering and amplifying module, connected to the output end of the first filtering and amplifying module, comprising a plurality of filtering and amplifying units, each of which is respectively used to perform a second-stage filtering and amplifying on the output signal of the first filtering and amplifying module based on different cutoff frequencies, wherein the plurality of filtering and amplifying units include a first filtering and amplifying unit and a second filtering and amplifying unit, the first filtering and amplifying unit is used to perform a second-stage filtering and amplifying on the output signal of the first filtering and amplifying module based on a first cutoff frequency, and the second filtering and amplifying unit is used to perform a second-stage filtering and amplifying on the output signal of the first filtering and amplifying module based on a second cutoff frequency; a third filtering and amplifying module, connected to the output end of the first filtering and amplifying unit, and performing a third-stage filtering and amplifying on the output signal of the first filtering and amplifying unit based on a third cutoff frequency; and a fifth amplifying module, connected to the output end of the second filtering and amplifying unit, and performing a third-stage amplifying on the output signal of the second filtering and amplifying unit. a bandwidth buffer module connected to the output end of the third filtering and amplifying module, for buffering and outputting the output signal of the third filtering and amplifying module, so as to provide a noise measurement channel with noise greater than the third cutoff frequency; a low-pass filtering module, comprising a plurality of low-pass filtering units with different cutoff frequencies, each of which is connected to the output end of the third filtering and amplifying module, and the low-pass filtering module is used to perform a fourth-stage filtering on the output signal of the third filtering and amplifying module, so as to provide a plurality of noise measurement channels with noise greater than the third cutoff frequency and less than different cutoff frequencies of a plurality of low-pass filtering units; a band-pass filtering module connected to the output end of the fifth amplifying module, for performing a third-stage filtering on the output signal of the fifth amplifying module based on the third cutoff frequency and the fourth cutoff frequency, so as to provide a noise measurement channel with noise greater than the fourth cutoff frequency and less than the third cutoff frequency; and a power supply module, respectively connected to the first filtering and amplifying module, the second filtering and amplifying module, the third filtering and amplifying module, the fifth amplifying module, the bandwidth buffer module, the low-pass filtering module and the band-pass filtering module, so as to provide a supply voltage.

[0007] Optionally, the universal noise measurement circuit also includes: a fourth high-pass filtering module, whose output end is connected to the first measurement port of the universal noise measurement circuit, and whose input end is respectively connected to the output ends of the bandwidth buffer module and the low-pass filtering module, so as to perform high-pass filtering on the output signals of the bandwidth buffer module and the low-pass filtering module respectively based on the third cutoff frequency; and a fifth high-pass filtering module, whose output end is connected to the second measurement port of the universal noise measurement circuit, and whose input end is connected to the output end of the band-pass filtering module, so as to perform high-pass filtering on the output signal of the band-pass filtering module based on the fourth cutoff frequency.

[0008] Optionally, the universal noise measurement circuit also includes: an indication module, including a first indicator light and a second indicator light, the indication module being connected to the output end of the third filtering and amplifying module and the output end of the fifth amplifying module, respectively, for selecting the corresponding first indicator light and second indicator light to light up according to the output signals of the third filtering and amplifying module and the fifth amplifying module.

[0009] Optionally, the first filtering and amplifying module includes: a first high-pass filtering unit, used to perform a first-stage high-pass filtering on the input noise signal to be measured; and a plurality of first amplifying units connected in parallel, connected to the output end of the first high-pass filtering unit, used to differentially amplify the output signal of the first high-pass filtering unit.

[0010] Optionally, the first high-pass filtering unit includes: a plurality of capacitors connected in parallel; a plurality of resistors connected between the negative terminals of the plurality of capacitors and a ground terminal; a first transistor, the collector of which is connected to the negative terminals of the plurality of capacitors, the base of which is connected to the ground terminal, and the emitter of which is suspended; a second transistor, the base of which is connected to the negative terminals of the plurality of capacitors, the collector of which is connected to the ground terminal, and the emitter of which is suspended, wherein the effective part of the plurality of resistors connected between the negative terminals of the plurality of capacitors and the ground terminal is adjustable.

[0011] Optionally, the universal noise measurement circuit further includes: a pre-charging unit connected to the plurality of capacitors and configured to pre-charge the plurality of capacitors, wherein the plurality of capacitors are all low leakage current capacitors.

[0012] Optionally, the first filtering and amplifying unit includes: a plurality of parallel second high-pass filtering units, which are connected one-to-one with the output ends of the plurality of parallel first amplifying units, and are used to perform a second stage high-pass filtering on the output signals of the plurality of parallel first amplifying units based on the first filtering frequency; a second amplifying unit, which is connected to the output ends of the plurality of parallel second high-pass filtering units, and is used to perform voltage amplification on the output signals of the plurality of parallel second high-pass filtering units, wherein the amplification factor of the second amplifying unit is adjustable.

[0013] Optionally, the second filtering and amplifying unit includes: a plurality of third high-pass filtering units connected in parallel, connected one-to-one with the output ends of the plurality of first parallel amplifying units, for performing a second stage high-pass filtering on the output signals of the plurality of first parallel amplifying units based on a second filtering frequency; a third amplifying unit connected to the output ends of the plurality of third high-pass filtering units connected in parallel, for performing voltage amplification on the output signals of the plurality of third high-pass filtering units connected in parallel, wherein the amplification factor of the third amplifying unit is adjustable.

[0014] Optionally, the third filtering and amplifying module includes: a fourth high-pass filtering unit, connected to the output end of the second amplifying unit, for performing a third-level high-pass filtering on the output signal of the second amplifying unit; a fourth amplifying unit, connected to the output end of the fourth high-pass filtering unit, for performing voltage amplification on the output signal of the fourth high-pass filtering unit, wherein the amplification factor of the fourth amplifying unit is adjustable.

[0015] Optionally, each of the low-pass filtering units is a fourth-order low-pass filter, and the band-pass filtering module is a fourth-order band-pass filter.

[0016] Optionally, the universal noise measurement circuit also includes: a first switch, connected between the output end of the bandwidth buffer module and the input end of the fourth high-pass filter module, and between the output end of each low-pass filter unit and the input end of the fourth high-pass filter module, and the multiple first switches are used to selectively connect the first measurement port with one of the multiple noise measurement channels corresponding to the bandwidth buffer module and the low-pass filter module.

[0017] Optionally, the first cut-off frequency is greater than the second cut-off frequency, the third cut-off frequency is greater than or equal to the first cut-off frequency, and the fourth cut-off frequency is greater than or equal to the second cut-off frequency.

[0018] Optionally, the power module includes: a battery pack, a charge and discharge protection circuit, a low-voltage dropout linear regulator and a second switch, the battery pack is connected to the first end of the second switch through the charge and discharge protection circuit; the external power supply port of the power module is connected to the second end of the second switch; the low-voltage dropout linear regulator is respectively connected to the third end of the second switch and the output end of the power module; wherein the second switch is used to select the electrical connection between the external power supply port, the output end of the power module and two of the battery pack.

[0019] According to the present invention, a universal noise measurement device is provided, which includes: a shielding box; at least one circuit board, on which the universal noise measurement circuit as described in any one of claims 1 to 13 is integrated, and the at least one circuit board is built into the shielding box and correspondingly connected to a plurality of connecting connectors arranged on the shielding box.

[0020] Optionally, the shielding box and the plurality of connecting connectors are all made of metal.

[0021] Optionally, the shell of the shielding box and the at least one circuit board are both single-point grounded.

[0022] The beneficial effects of the present invention are as follows: the present invention discloses a universal noise measurement circuit and device, which performs multi-stage filtering and amplification on an input noise signal to be measured through a multi-stage filtering and amplification module, and simultaneously generates at least two intermediate signals to be measured with different cutoff frequencies in the process, thereby providing the possibility of simultaneously testing the noise signal to be measured within two different noise parameter (noise frequency) ranges, thereby avoiding test errors caused by changes in the test environment and the test system. For the first of the at least two signals to be tested, after further filtering by using a bandwidth buffer module and a low-pass filter module, a noise measurement channel with noise greater than the third cutoff frequency and multiple noise measurement channels with noise greater than the third cutoff frequency and less than different cutoff frequencies of multiple low-pass filter units can be obtained respectively. For the second of the at least two signals to be tested, after filtering by using a bandpass filter, a noise measurement channel with noise greater than the fourth cutoff frequency and less than the third cutoff frequency can be obtained. Therefore, based on the above multiple different noise measurement channels, the present disclosure can meet the filtering and amplification of all noise parameters based on one circuit, and thus can meet the noise measurement requirements for different chips and circuits (such as different operational amplifiers, LDOs and REFs), and has strong versatility. On the other hand, the circuit disclosed in the present disclosure can also effectively filter out the interference of redundant noise and background noise of the circuit through multi-level filtering during the noise measurement process, thereby ensuring the integrity of the input noise signal to be tested.

[0023] By performing high-pass filtering on the output signals of the noise measurement channels corresponding to the first and second of the at least two signals to be measured respectively through the fourth high-pass filtering unit and the fifth high-pass filtering unit, the background low-frequency noise of the universal noise measurement circuit itself disclosed in the present invention can be filtered out, thereby improving the accuracy of the noise measurement result.

[0024] The indication module is provided with a first indicator light and a second indicator light respectively corresponding to the first and second signals to be tested of the at least two signals to be tested. Therefore, the working conditions of the corresponding measurement channels can be indicated, thereby improving the convenience and observability of the measurement. At the same time, it can also detect whether each measurement channel is in a normal state, which helps to improve the reliability of the measurement results.

[0025] Two transistors are set in the first-stage filter unit for input of the noise signal to be measured for clamping, which reduces the influence of leakage current in the circuit on the noise measurement accuracy. At the same time, low leakage current capacitors and pre-charging units are used in the first-stage filter unit to reduce the charging time of the first-stage filter unit, improve the measurement efficiency and the accuracy of the measurement results. Furthermore, the filtering frequency of the first-stage filter unit is adjustable, so that different background noises corresponding to different circuits or chips to be tested can be filtered out when the noise model to be tested is input, further improving the versatility of the circuit.

[0026] The amplification unit in the first filtering and amplifying module adopts differential amplification, which has low self-noise and can also reduce the interference between at least two intermediate test signals obtained based on different cutoff filtering, thereby providing a guarantee for the simultaneous testing of the test noise signal within two different noise parameter (noise frequency) ranges.

[0027] The power module uses a built-in battery pack, charge and discharge protection circuit and low voltage difference linear regulator, and reserves a battery charging interface and selection switch. The battery or external power supply can be switched through the control switch, which solves the power supply noise interference. When the battery pack is low on power, you can choose to use an external power supply for testing, which improves the adaptability to different test environments.

[0028] In the noise measurement device, the noise measurement circuit (including the circuit itself and the power board) is placed in a shielding box, powered by a built-in lithium battery to further reduce power supply noise. The shell and the circuit board are single-point grounded, and the external connectors are made of metal to further ensure the integrity of the shielding layer, effectively avoiding the noise that may be caused by external magnetic field interference.

[0029] It should be noted that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0031] Figure 1 A system block diagram of a general noise measurement circuit provided according to an embodiment of the present disclosure is shown;

[0032] Figure 2A schematic diagram showing the structure of a power supply module in a universal noise measurement circuit provided according to an embodiment of the present disclosure is shown;

[0033] Figure 3 A pin diagram of a power module provided according to an embodiment of the present disclosure is shown;

[0034] Figures 4 to 13 Schematic diagrams of the circuit structures of various modules in the universal noise measurement circuit provided according to the embodiments of the present disclosure are respectively shown;

[0035] Fig.14 A schematic diagram showing the structure of a universal noise measurement device provided according to an embodiment of the present disclosure is shown;

[0036] Fig.15a and Fig.15b The schematic diagrams of the structures of the front and rear panels of the universal noise measurement device provided according to the embodiments of the present disclosure are respectively shown. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0039] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0040] Figure 1 A system block diagram of a general noise measurement circuit provided according to an embodiment of the present disclosure is shown. Figure 2 A schematic diagram showing the structure of a power supply module in a universal noise measurement circuit provided according to an embodiment of the present disclosure is shown. Figure 3 A pin diagram of a power module provided according to an embodiment of the present disclosure is shown. Figures 4 to 13 The circuit structure schematic diagrams of each module in the universal noise measurement circuit provided according to the embodiments of the present disclosure are respectively shown.

[0041] like Figure 1As shown, in this embodiment, the universal noise measurement circuit includes: a power supply module 100, a first filtering and amplifying module 200, a second filtering and amplifying module 300, a third filtering and amplifying module 400, a fifth amplifying module 600, a bandwidth buffer module 510, a low-pass filtering module 520, a band-pass filtering module 700, a fourth high-pass filtering module 810, a fifth high-pass filtering module 820 and an indication module 900.

[0042] The power supply module 100 is respectively connected to the first filter amplifier module 200, the second filter amplifier module 300, the third filter amplifier module 400, the fifth amplifier module 600, the bandwidth buffer module 510, the low-pass filter module 520, the band-pass filter module 700, the fourth high-pass filter module 810, the fifth high-pass filter module 820 and the indication module 900 to increase the power supply voltage. Figure 2 and Figure 3 The power module 100 includes a battery pack 110, a charge and discharge protection circuit 120, a second switch 130, and a low voltage drop linear regulator 140. The battery pack 110 is connected to the first end of the second switch 130 through the charge and discharge protection circuit 120; the external power supply port of the power module 100 is connected to the second end of the second switch 130; the low voltage drop linear regulator is connected to the third end of the second switch 130 and the output end of the power module 100 respectively. Among them, the second switch 130 is used to select the electrical connection between the external power supply port of the power module, the output end of the power module, and the battery pack 110.

[0043] When the second switch 130 connects the electrical connection between the external power supply port of the power module and the output end of the power module, the universal noise measurement circuit disclosed in this embodiment is directly powered by an external power supply. When the second switch 130 connects the electrical connection between the output end of the power module and the battery pack 110, the universal noise measurement circuit disclosed in this embodiment is powered by a built-in battery pack. When the second switch 130 is used to select the electrical connection between the external power supply port of the power module and the battery pack 110, the universal noise measurement circuit disclosed in this embodiment is charged by an external power supply to the built-in battery pack. Powering the noise measurement circuit with the built-in battery pack 110 can further reduce power supply noise, and switching the built-in battery pack 110 or external power supply through the second switch 130 solves the power supply noise interference. At the same time, when the battery power is low, it can choose to use an external power supply for testing or charging the battery pack 110, ensuring continuous measurement of noise and improving adaptability to different application environments.

[0044] Optionally, the second switch 130 may be any one of a push switch, a knob switch, a slide switch and a toggle switch.

[0045] Optionally, the external power supply port of the power module 100 may be only a commonly used AC power receiving port, which outputs a suitable voltage to the battery pack 110 for charging after passing through a corresponding step-down circuit or directly outputs it to the output end of the power module 100 to provide the power supply voltage required by the circuit. The external power supply port of the power module 100 may also include a commonly used AC power receiving port and at least one low-voltage receiving port at the same time, wherein the AC power receiving port is used to output a suitable voltage to the battery pack 110 for charging after passing through a corresponding step-down circuit, and the low-voltage receiving port is used to receive a DC signal of the power supply voltage value required for the operation of the corresponding circuit and the charging voltage required for charging the battery pack, so as to directly output it to the output end of the power module 100 when external power supply is required. The present invention is not limited to this.

[0046] In one embodiment of the present disclosure, the universal noise measurement circuit is also provided with a corresponding status indicator light, which is connected to the power module 110, and presents different indication information according to different working modes of the power module 100 or different setting states of the second switch 130. For example, the status indicator light is provided in multiple numbers, each of which corresponds to a working mode of the power module 100 or a setting state of the second switch 130, and presents indication information by lighting; or the status indicator light is provided in one number, but it can present different colors, and the status indicator light presents different indication information by changing the color when it is lit. In this way, usability can be enhanced.

[0047] like Figure 3 As shown, in this embodiment, one of the power chips corresponding to the power module 100 includes pins 1 to 6. Among them, pin 1 is the first positive power supply voltage pin VCC1, pin 2 is the ground pin GND, pin 3 is the first negative power supply voltage pin VDD1, pin 4 is the second positive power supply voltage pin VCC2, pin 5 is the ground pin GND, and pin 6 is the second negative power supply voltage pin VDD2. Figure 2 , the above pins 1 to 3 may be connected to the external power supply port of the power module 100, and pins 4 to 6 may be connected to the output end of the power module 100. That is to say, whether it is pins 1 to 3 or pins 4 to 6, they can provide power supply voltage for the universal noise measurement circuit in the present disclosure. It can be understood that the power chip may include other pins connected to the battery pack and pins connected to the second switch 130.

[0048] The first filtering and amplifying module 200 receives the noise signal to be measured, and is used to perform first-stage filtering and amplification on the received noise signal to be measured. The first filtering and amplifying module 200 includes a first high-pass filtering unit 210 and a plurality of first amplifying units 220 connected in parallel.

[0049] The first high-pass filtering unit 210 is used to perform a first stage high-pass filtering on the input noise signal to be measured.

[0050] Combination Figure 4 In this embodiment, the first high-pass filter unit 210 can be selected as a passive high-pass filter, which specifically includes: a plurality of capacitors C1-C10 connected in parallel, a first multiple-choice selection switch U1, a plurality of resistors R1-R4, a first transistor Q1 and a second transistor Q2. Among them, the positive terminals of the plurality of capacitors C1-C10 are connected to the input port Input of the noise signal to be measured, the negative terminals of the plurality of capacitors C1-C10 are connected to the output terminal of the first multiple-choice selection switch U1, and the plurality of resistors R1-R4 are respectively connected between the plurality of input terminals of the first multiple-choice selection switch U1 and the ground terminal. Among them, the resistance value of each resistor in the plurality of resistors R1-R4 is different. The different resistors selected by the first multiple-choice selection switch U1 to access the circuit have different filtering frequencies (cut-off frequencies) of the corresponding first high-pass filter unit 210, thereby realizing the adjustment of the filtering frequency, which can play a good filtering role on the background noise of different circuits or chips to be measured, and further improve the versatility of the circuit. Further, the collector of the first transistor Q1 is connected to the negative terminals of the plurality of capacitors C1 to C10 connected in parallel, the base of the first transistor Q1 is connected to the ground terminal, the emitter of the first transistor Q1 is suspended, the base of the second transistor Q2 is connected to the negative terminals of the plurality of capacitors C1 to C10 connected in parallel, the collector of the second transistor Q2 is connected to the ground terminal, and the emitter of the second transistor Q2 is suspended. The first transistor Q1 and the second transistor Q2 are used to clamp the output signal V1 of the first high-pass filter unit 210 to reduce the influence of leakage current in the circuit on the noise measurement accuracy.

[0051] Furthermore, the first high-pass filter unit 210 also includes: a pre-charging unit 211 and a third switch 213. Among them, the pre-charging unit 211 is connected to a plurality of capacitors C1 to C10, and is used to pre-charge the plurality of capacitors C1 to C10. The third switch 213 is connected between the pre-charging unit 211 and the plurality of capacitors C1 to C10, and is used to start or shut down the pre-charging action of the pre-charging unit 211 on the plurality of capacitors C1 to C10. At the same time, the plurality of resistors C1 to C10 are all low leakage current capacitors. In this way, the charging time of the plurality of capacitors C1 to C10 in the first-stage filter unit 210 can be reduced, thereby improving the measurement efficiency and the accuracy of the measurement results.

[0052] Optionally, the third switch 213 may be any one of a key switch, a knob switch, a slide switch and a toggle switch.

[0053] A plurality of first amplifying units 220 connected in parallel are connected to the output end of the first high-pass filtering unit 210 , and are used to differentially amplify the output signal V1 of the first high-pass filtering unit 210 .

[0054] Combination Figure 5a and Figure 5b In this embodiment, each of the multiple parallel first amplifying units 220 is provided with a differential amplification structure, and the output after differential amplification is used as the input of the operational amplifier, so as to suppress the temperature drift when the nV level noise signal to be measured is amplified by a high multiple, and ensure the accuracy of the subsequent noise measurement results. Exemplarily, in this embodiment, four parallel first amplifying units are included in the multiple parallel first amplifying units 220 as an example for specific description: the first first discharge unit of the four parallel first amplifying units includes resistors R5-R10, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, capacitors C11-C12 and an operational amplifier U2. Among them, the resistors R5~R8, the third transistor Q3, the fourth transistor Q4, the fifth transistor Q5, the sixth transistor Q6 and the capacitor C11 together form a differential amplifier structure to differentially amplify the output signal V1 of the first high-pass filter unit 210. At the same time, the first output signal of the differential amplifier structure is output to the inverting input terminal of the operational amplifier U2 after passing through the resistor R9, and the second output signal of the differential amplifier structure is output to the non-inverting input terminal of the operational amplifier U2 after passing through the resistor R10. The capacitor C12 is connected between the inverting input terminal and the output terminal of the operational amplifier U2, and the output terminal of the operational amplifier U2 is the output terminal of the first first discharge unit. Furthermore, the second first discharge unit of the four parallel first amplifying units includes resistors R15~R20, transistors Q7~Q10, capacitors C15~C16 and an operational amplifier U3; the third first discharge unit of the four parallel first amplifying units includes resistors R25~R30, transistors Q11~Q14, capacitors C19~C20 and an operational amplifier U4; the fourth first discharge unit of the four parallel first amplifying units includes resistors R35~R40, transistors Q15~Q18, capacitors C23~C24 and an operational amplifier U5, but it can be understood that the structure of each first amplifying unit in the multiple parallel first amplifying units 220 is the same, which will not be repeated here.

[0055] The second filtering and amplifying module 300 is connected to the output end of the first filtering and amplifying module 200, and includes a plurality of filtering and amplifying units, each of which is used to perform a second stage filtering and amplification on the output signal of the first filtering and amplifying module 200 based on a different cutoff frequency.

[0056] It can be understood that the number of filter amplification units in the second filter amplification module 300 is related to the number of measurement ports of the universal noise measurement circuit of the present invention that can simultaneously perform noise measurement. For example, when the number of filter amplification units in the second filter amplification module 300 is 5, the universal noise measurement circuit of the present invention can be set to 5 noise measurement ports, and then the input noise signal to be measured can be simultaneously measured in 5 different measurement ranges. Exemplarily, in this embodiment, the number of filter amplification units in the second filter amplification module 300 is 2 (i.e., including the first filter amplification unit 310 and the second filter amplification unit 320), but it should be understood that the number 2 should not be a limitation of the present invention.

[0057] Among them, the first filter amplification unit 310 is used to perform a second stage of filtering and amplification on the output signal of the first filter amplification module 200 based on the first cut-off frequency. Furthermore, the first filter amplification unit 310 includes: a plurality of parallel second high-pass filter units and a second amplification unit 312. The plurality of parallel second high-pass filter units are connected one-to-one with the output ends of the plurality of parallel first amplification units 220, and are used to perform a second stage of high-pass filtering on the output signals of the plurality of parallel first amplification units 220 based on the first filtering frequency (i.e., the first cut-off frequency). Exemplarily, in this embodiment, four parallel second high-pass filter units are included in the plurality of parallel second high-pass filter units as an example for specific description: the first second high-pass filter unit 311 among the four parallel second high-pass filter units is a passive high-pass filter, refer to Figure 5a and Figure 5b, specifically including a capacitor C13 and resistors R11-R12. Among them, a first end of the capacitor C13 is connected to the output end of the first first amplifying unit among the plurality of first amplifying units 220 connected in parallel, a second end of the capacitor C13 outputs the filtered signal V2 at a node b through the resistor C13, and the resistors R11-R12 are connected between the output end of the first first amplifying unit and the ground end. Further, the second second high-pass filtering unit 311 of the four parallel second high-pass filtering units is connected to the output end of the second first amplifying unit, includes a capacitor C17 and resistors R21~R22, and outputs the filtered signal V2 at node b through resistor R23; the third second high-pass filtering unit 311 of the four parallel second high-pass filtering units is connected to the output end of the third first amplifying unit, includes a capacitor C21 and resistors R31~R32, and outputs the filtered signal V2 at node b through resistor R33; the fourth second high-pass filtering unit 311 of the four parallel second high-pass filtering units is connected to the output end of the fourth first amplifying unit, includes a capacitor C25 and resistors R41~R42, and outputs the filtered signal V2 at node b through resistor R43, but it can be understood that the structure of each second high-pass filtering unit in the multiple parallel second high-pass filtering units is the same, which will not be repeated here, and the output of each second high-pass filtering unit is commonly used as the input of the subsequent second amplifying unit 312.

[0058] The second amplifying unit 312 is connected to the output ends of the plurality of second high-pass filtering units connected in parallel, and is used to amplify the voltage of the output signal V2 of the plurality of second high-pass filtering units connected in parallel. Figure 6 Exemplarily, the second amplifying unit 312 includes a second multiple-choice selection switch U6, a plurality of resistors R45-R46 and an operational amplifier U7. The inverting input terminal of the operational amplifier U7 receives the output signals V2 of the plurality of second high-pass filter units, the non-inverting input terminal of the operational amplifier U7 is grounded, and the output terminal of the operational amplifier U7 is used as the output terminal of the first filtering amplifying unit 310. The plurality of input terminals of the second multiple-choice selection switch U6 are connected to the inverting input terminal of the operational amplifier U7 after passing through a plurality of resistors R45-R46, and the output terminal of the second multiple-choice selection switch U6 is connected to the output terminal of the operational amplifier U7. The resistance value of each of the plurality of resistors R45-R46 is different. The effective amplification factor of the second amplifying unit 312 is also different when the resistors connected to the circuit are selected by the second multiple-choice selection switch U6, thereby realizing the adjustment of the amplification factor of the second amplifying unit 312. It should be understood that the above is merely exemplary, and the present disclosure does not limit the number of the plurality of resistors and the number of adjustable levels of the amplification factor of the second amplifying unit 312 .

[0059] The second filter amplification unit 320 is used to perform a second stage of filtering and amplification on the output signal of the first filter amplification module 200 based on the second cutoff frequency. Further, the second filter amplification unit 320 includes: a plurality of parallel third high-pass filter units and a third amplification unit 322. The plurality of parallel third high-pass filter units are connected one-to-one with the output ends of the plurality of parallel first amplification units 220, and are used to perform a second stage of high-pass filtering on the output signals of the plurality of parallel first amplification units 220 based on the second filtering frequency (i.e., the second cutoff frequency). Exemplarily, in this embodiment, four parallel third high-pass filter units are included in the plurality of parallel third high-pass filter units as an example for specific description: the first third high-pass filter unit 321 among the four parallel third high-pass filter units is a passive high-pass filter, refer to Figure 5a and Figure 5b , specifically including a capacitor C14 and a resistor R14. The first end of the capacitor C14 is connected to the output end of the first first amplifying unit among the plurality of first amplifying units 220 connected in parallel, the second end of the capacitor C14 outputs the filtered signal V3 at a node a, and the resistor R14 is connected between the second end of the capacitor C14 and the ground end. Furthermore, the second third high-pass filtering unit 321 among the four parallel third high-pass filtering units is connected to the output end of the second first amplifying unit, includes a capacitor C18 and a resistor R24, and outputs a filtered signal V3 at node a; the third third high-pass filtering unit 321 among the four parallel third high-pass filtering units is connected to the output end of the third first amplifying unit, includes a capacitor C22 and a resistor R34, and outputs a filtered signal V3 at node a; the fourth third high-pass filtering unit 321 among the four parallel third high-pass filtering units is connected to the output end of the fourth first amplifying unit, includes a capacitor C26 and a resistor R44, and outputs a filtered signal V3 at node a, but it can be understood that the structure of each third high-pass filtering unit in the multiple parallel third high-pass filtering units is the same, which will not be repeated here, and the output of each third high-pass filtering unit is commonly used as the input of the subsequent third amplifying unit 322.

[0060] The third amplifying unit 322 is connected to the output ends of the plurality of third high-pass filtering units connected in parallel, and is used to amplify the voltage of the output signal V3 of the plurality of third high-pass filtering units connected in parallel. Figure 7Exemplarily, the third amplifying unit 322 includes a third multiple-choice selection switch U10, a capacitor C29, a plurality of resistors R49-R51 and an operational amplifier U9. Among them, the non-inverting input terminal of the operational amplifier U9 receives the output signal V3 of the plurality of third high-pass filter units, the inverting input terminal of the operational amplifier U9 is grounded through the resistor R49, and the output terminal of the operational amplifier U9 is used as the output terminal of the second filter amplifying unit 320. The capacitor C29 is connected between the inverting input terminal of the operational amplifier U9 and the output terminal of the operational amplifier U9. The plurality of input terminals of the third multiple-choice selection switch U10 are respectively grounded after passing through the resistors R50-R51, and the output terminal of the third multiple-choice selection switch U10 is connected to the output terminal of the operational amplifier U9. Among them, the resistance value of each resistor in the resistors R50-R51 is different. The effective amplification factor of the third amplifying unit 322 is also different by selecting different resistors in the circuit connected by the third multiple-choice selection switch U10, thereby realizing the adjustment of the amplification factor of the third amplifying unit 322. It should be understood that the above is merely exemplary, and the present disclosure does not limit the number of the plurality of resistors and the number of adjustable levels of the amplification factor of the third amplifying unit 322 .

[0061] Optionally, an additional high-pass filter may be further provided after the output end of the third amplifying unit 322 to filter the output signal of the third filtering and amplifying unit 320 again based on the fourth cutoff frequency.

[0062] The third filter amplification module 400 is connected to the output end of the first filter amplification unit 310 among the plurality of filter amplification units to perform a third level of filter amplification on the output signal of the first filter amplification unit 310 based on the third cutoff frequency. The third filter amplification module 400 includes: a fourth high-pass filter unit 410 and a fourth amplification unit 420.

[0063] The fourth high-pass filter unit 420 is connected to the output end of the second amplifying unit 312 to perform a third-stage high-pass filtering on the output signal of the second amplifying unit 312. In this embodiment, the fourth high-pass filter unit 420 is a second-order active high-pass filter. Figure 6 , exemplarily, the fourth high-pass filter unit 420 specifically includes: capacitors C27-C28, resistors R47-R48 and operational amplifier U8. Among them, the capacitors C27-C28 are sequentially connected in series between the output end of the second amplification unit 312 and the non-inverting input end of the operational amplifier U8, the non-inverting input end of the operational amplifier U8 is also connected to the ground end through the resistor R48, the inverting input end of the operational amplifier U8 is connected to its output end, the resistor R47 is connected between the connection point of the capacitor C27 and the capacitor C28 and the inverting input end of the operational amplifier U8, and the output end of the operational amplifier U8 outputs the signal V4 after the third stage filtering.

[0064] The fourth amplifying unit 420 is connected to the output end of the fourth high-pass filtering unit 410 to amplify the voltage of the output signal V4 of the fourth high-pass filtering unit 410. Figure 8 Exemplarily, the fourth amplifier unit 420 includes resistors R52 to R4, a fourth multi-selection switch U12, and an operational amplifier U11. The circuit structure of the fourth amplifier unit 420 is substantially the same as that of the second amplifier unit 312, and will not be described in detail herein. The output end of the operational amplifier U11 corresponds to the node c. It should be noted that by setting different resistance values ​​in the fourth amplifier unit 420 and the second amplifier unit 312, different amplification factors can be achieved. Therefore, the resistance value in the fourth amplifier unit 420 and the resistance value in the second amplifier unit 312 may be the same or different, and should be set accordingly according to actual needs. Accordingly, the amplification factor of the fourth amplifier unit 420 is also adjustable.

[0065] The fifth amplifying module 600 is connected to the output end of the second filtering and amplifying unit 320 among the plurality of filtering and amplifying units, and is used to perform a third stage amplification on the output signal of the second filtering and amplifying unit 320 .

[0066] refer to Fig. 9 , exemplarily, the fifth amplification module 600 includes resistors R55-R58, capacitors C30-C31, an operational amplifier U13, and a fifth multiple-choice selection switch U14. Among them, the non-inverting input terminal of the operational amplifier U13 receives the signal V5 through the resistor R55, the inverting input terminal of the operational amplifier U13 is connected to the ground terminal through the resistor R56, the capacitor C30 and the capacitor C31 connected in series in sequence, and the output terminal (corresponding to the node d) of the operational amplifier U13 outputs the signal V7 after the third-stage amplification of the output signal of the second filter amplifier unit 320. The multiple input terminals of the fifth multiple-choice selection switch U14 are respectively connected to the inverting input terminal of the operational amplifier U13 through the resistor R57 and the resistor R58, and the output terminal of the fifth multiple-choice selection switch U14 is connected to the output terminal of the operational amplifier U13. Among them, the adjustment of the amplification factor of the fifth amplification module 600 can be realized based on the fifth multiple-choice selection switch U14.

[0067] The bandwidth buffer module 510 is connected to the output end of the third filter amplification module 400 to buffer the output signal V6 of the third filter amplification module 300 to provide a noise measurement channel with noise greater than the third cutoff frequency. Fig.10, the bandwidth buffer module 510 can be a voltage follower, including an operational amplifier U15. The inverting input terminal of the operational amplifier U15 is connected to the output terminal, the non-inverting input terminal of the operational amplifier U15 is connected to the output terminal of the third filtering and amplifying module 400, and the output terminal of the operational amplifier U15 provides an output signal V8 after signal following. Since the frequency of the output signal V6 of the third filtering and amplifying module 400 is greater than the third cut-off frequency, the frequency of the output signal V8 of the bandwidth buffer module 510 is also greater than the third cut-off frequency, that is, the noise measurement range based on the output terminal of the bandwidth buffer module 510 is from the third cut-off frequency to infinity.

[0068] The low-pass filter module 520 includes a plurality of low-pass filter units with different cut-off frequencies, each of which is connected to the output end of the third filter amplification module 400, and the low-pass filter module 520 is used to perform a fourth-stage filtering on the output signal of the third filter amplification module 400 to provide a plurality of noise measurement channels with noise greater than the third cut-off frequency and less than the different cut-off frequencies of the plurality of low-pass filter units. The low-pass filter module 520 includes but is not limited to a first low-pass filter unit and a second low-pass filter unit. The first low-pass filter unit performs a fourth-stage filtering on the output signal V6 of the third filter amplification module 400 based on the fifth cut-off frequency and outputs a signal V9, and the second low-pass filter unit performs a fourth-stage filtering on the output signal V6 of the third filter amplification module 400 based on the sixth cut-off frequency and outputs a signal V10. The fifth cut-off frequency and the sixth cut-off frequency are both greater than the third cut-off frequency, such as the fifth cut-off frequency is 1MHz, and the sixth cut-off frequency is 100KHz. It can be understood that the multiple low-pass filter units with different cutoff frequencies in the low-pass filter module 520 are respectively used to provide measurement channels with different measurement accuracy and different measurement upper limit values ​​based on the third cutoff frequency to meet the measurement requirements of different circuits or chips.

[0069] Further, in the present disclosure, the circuit structures of the multiple low-pass filter units with different cut-off frequencies in the low-pass filter module 520 are substantially the same. For example, in one embodiment of the present invention, reference is made to Fig.10, the first low-pass filter unit includes resistors R59-R62, capacitors C33-C36 and operational amplifiers U16-U17. The second low-pass filter unit includes resistors R63-R66, capacitors C37-C40 and operational amplifiers U18-U19. Among them, the first low-pass filter unit and the second low-pass filter unit are both structures of fourth-order low-pass filters, and their specific circuit structures are not repeated here. Since the frequency of the output signal V6 of the third filtering and amplifying module 400 is greater than the third cut-off frequency, the frequency of the output signal V9 of the first low-pass filter unit of the low-pass filter module 520 is greater than the third cut-off frequency and less than the fifth cut-off frequency, and the frequency of the output signal V10 of the second low-pass filter unit of the low-pass filter module 520 is greater than the third cut-off frequency and less than the sixth cut-off frequency. That is to say, the noise measurement range based on the output end of the first low-pass filter unit of the low-pass filter module 520 is between the third cut-off frequency and the fifth cut-off frequency, and the noise measurement range based on the output end of the second low-pass filter unit of the low-pass filter module 520 is between the third cut-off frequency and the sixth cut-off frequency.

[0070] Furthermore, the universal noise measurement circuit of the present disclosure further includes a fourth high-pass filter module 810. The output end of the fourth high-pass filter module 810 is connected to the first measurement port Output1 of the universal noise measurement circuit, and the input end of the fourth high-pass filter module 810 is respectively connected to the output ends of the bandwidth buffer module 510 and the low-pass filter module 520, so as to perform high-pass filtering on the output signals V8, V9 and V10 of the bandwidth buffer module 510 and the low-pass filter module 520 respectively based on the third cutoff frequency. For example, reference Fig.11 , the fourth high-pass filter module 810 is a first-order passive high-pass filter, including a plurality of capacitors C41 to C47 and a resistor R67 connected in parallel. Among them, the resistor R67 is connected between the negative terminals of the plurality of capacitors C41 to C47 and the ground terminal. The negative terminals of the plurality of capacitors C41 to C47 are connected to the first measurement port Output1. Further, the fourth high-pass filter module 810 also includes a first switch U20. The input terminal of the first switch U20 is respectively connected to the output terminals of the bandwidth buffer module 510 and the low-pass filter module 520, and the output terminal of the first switch U20 is connected to the positive terminals of the plurality of capacitors C41 to C47. The first switch U20 is used to select the output terminal of the bandwidth buffer module 510 and one of the plurality of output terminals of the low-pass filter module 520 to be connected to the first measurement port Output1. Since the fourth high-pass filter module 810 can filter out signals below the third cutoff frequency, the background low-frequency noise of the universal noise measurement circuit of the present disclosure can be filtered out when the first measurement port Output1 is selected for noise measurement, thereby improving the accuracy of the noise measurement result.

[0071] Optionally, the first switch U20 may be any one of a push switch, a knob switch, a sliding switch and a toggle switch.

[0072] The bandpass filter module 700 is connected to the output end of the fifth amplification module 600, and is used to perform a third-stage filtering on the output signal V7 of the fifth amplification module 600 based on the third cutoff frequency (upper cutoff frequency) and the fourth cutoff frequency (fourth cutoff frequency), so as to provide a noise measurement channel with noise greater than the fourth cutoff frequency and less than the third cutoff frequency. Exemplarily, in one embodiment of the present invention, reference Fig.12 The bandpass filter module 700 includes resistors R68-R73, capacitors C48-C51 and operational amplifiers U21-U22. The bandpass filter module 700 is a common fourth-order bandpass filter structure, and its specific circuit structure is not repeated here. Due to the upper and lower cutoff frequencies of the bandpass filter module 700, the noise measurement range based on the output end of the bandpass filter module 700 is between the fourth cutoff frequency and the third cutoff frequency.

[0073] Furthermore, the universal noise measurement circuit of the present disclosure further includes a fifth high-pass filter module 820. The output end of the fifth high-pass filter module 820 is connected to the second measurement port Output2 of the universal noise measurement circuit, and the input end of the fifth high-pass filter module 820 is connected to the output end of the band-pass filter module 700, so as to perform high-pass filtering on the output signal of the band-pass filter module 700 based on the fourth cutoff frequency. For example, reference Fig.12 The fifth high-pass filter module 820 is a first-order passive high-pass filter, including a plurality of capacitors C52 to C56 and a resistor R74 connected in parallel. The resistor R74 is connected between the negative terminals of the plurality of capacitors C52 to C56 and the ground terminal. The negative terminals of the plurality of capacitors C52 to C56 are connected to the second measurement port Output2. Since the fifth high-pass filter module 820 can filter out signals below the fourth cutoff frequency, the background low-frequency noise of the universal noise measurement circuit of the present disclosure can be filtered out when the second measurement port Output2 is selected for noise measurement, thereby improving the accuracy of the noise measurement result.

[0074] Optionally, the present disclosure may further provide an additional low-pass filter between the output end of the fifth amplification module 600 and the input end of the band-pass filtering module 700. The low-pass filter is used to filter the output signal of the fifth amplification module 600 again based on the third cut-off frequency. In the present invention, by providing an additional high-pass filter and an additional low-pass filter between the circuit noise signal input port and the second measurement port, and double filtering of the band-pass filter 700, the filtering of the noise signal to be measured based on the frequency measurement range between the fourth cut-off frequency and the third cut-off frequency can be made more accurate, and the accuracy and reliability of the noise measurement result can be further improved.

[0075] The indication module 900 includes a first indicator light and a second indicator light, and the indication module 900 is respectively connected to the output end (i.e., node c) of the third filtering and amplifying module 400 and the output end (node ​​d) of the fifth amplifying module 600, so as to select the corresponding first indicator light and second indicator light according to the output signals of the third filtering and amplifying module 400 and the fifth amplifying module 600. For example, refer to Fig.13 , the indicating module 900 includes a sixth multiple-choice selection switch U23, resistors R75-R78, transistors Q19 and Q20, and light-emitting diodes LED1 and LED2. Among them, the first input end of the sixth multiple-choice selection switch U23 is connected to the output end (i.e., node c) of the third filtering and amplifying module 400, the second input end of the sixth multiple-choice selection switch U23 is connected to the output end (node ​​d) of the fifth amplifying module 600, and the output end of the sixth multiple-choice selection switch U23 is connected to the base of the transistor Q19 through the resistor R75, and is also connected to the base of the transistor Q20 through the resistor R76. The emitter of the transistor Q19 receives the power supply voltage VCC1, the collector of the transistor Q19 is connected to the anode of the light-emitting diode LED1 through the resistor R77, and the cathode of the light-emitting diode LED1 is connected to the ground end. The emitter of transistor Q20 receives the power supply voltage VDD1, the collector of transistor Q20 is connected to the cathode of the light emitting diode LED2 through resistor R78, and the anode of the light emitting diode LED2 is connected to the ground terminal. Among them, transistor Q19 is a PNP transistor, and transistor Q20 is an NPN transistor.

[0076] Further, when the first measurement port Output1 is selected for measurement, the sixth multiple-choice selection switch U23 selects its first input end (the input end connected to the node c) to be connected to its output end, and when the second measurement port Output2 is selected for measurement, the sixth multiple-choice selection switch U23 selects its second input end (the input end connected to the node d) to be connected to its output end. Afterwards, when the output end of the sixth multiple-choice selection switch U23 outputs a high level, it indicates that a signal is flowing on the currently selected measurement channel, at which time the transistor Q19 is turned off, the transistor Q20 is turned on, the light-emitting diode LED1 does not emit light, and the light-emitting diode LED2 emits light normally; when the output end of the sixth multiple-choice selection switch U23 outputs a low level, it indicates that there is no signal flowing on the currently selected measurement channel, at which time the transistor Q19 is turned on, the transistor Q20 is turned off, the light-emitting diode LED1 emits light normally, and the light-emitting diode LED2 does not emit light. That is to say, when the light-emitting diode LED1 is on, it indicates that there is no signal flowing on the current measurement channel, and when the light-emitting diode LED2 is on, it indicates that there is a signal flowing on the current measurement channel. Since the light-emitting diodes LED1 and LED2 do not light up at the same time, the purpose of indication can be achieved. Therefore, the working status of the corresponding measurement channel can be indicated, the convenience and observability of the measurement can be improved, and at the same time, it can also detect whether each measurement channel is in a normal state, which helps to improve the reliability of the measurement results.

[0077] Further, in the present disclosure, the first cutoff frequency is greater than the second cutoff frequency, the third cutoff frequency is greater than or equal to the first cutoff frequency, and the fourth cutoff frequency is greater than or equal to the second cutoff frequency. For example, the first cutoff frequency is 5 Hz, the second cutoff frequency is 0.07 Hz, the third cutoff frequency is 10 Hz, and the fourth cutoff frequency is 0.1 Hz.

[0078] It is understandable that the resistance value of each resistor and the capacitance value of each capacitor in the above modules and units can be set according to actual conditions as long as the above filtering and voltage amplification requirements can be met.

[0079] It should be noted that the power supply terminals of each operational amplifier in the universal noise measurement circuit of the present invention and other devices or circuit structures that require power supply voltage to operate normally are connected to the corresponding ports of the power module 100, receiving the corresponding power supply voltages VCC1 and VDD1 or VCC2 and VDD2, and the reference ground voltage GND for normal operation.

[0080] It should be noted that in the present disclosure, each of the above-mentioned multiple-choice selection switches can be a switch chip driven based on a control signal, or a mechanical switch such as the first switch U20, the second switch 130 and the third switch 213, or a connector connected based on a jumper cap.

[0081] It should be noted that the power supply end of each of the above remote amplifiers is also connected to the ground end through a capacitor to filter the received power supply voltage to achieve stable operation of each remote amplifier.

[0082] Fig.14 A schematic diagram showing the structure of a universal noise measurement device provided according to an embodiment of the present disclosure is shown. Fig.15a and Fig.15b The schematic diagrams of the structures of the front and rear panels of the universal noise measurement device provided according to the embodiments of the present disclosure are respectively shown.

[0083] like Fig.14 As shown, in this embodiment, the universal noise measuring device includes a shielding box 11 and at least one circuit board 1 placed in the shielding box 1 .

[0084] Among them, the side of the housing of the shielding box 1 is provided with a plurality of connecting plugs for realizing signal transmission. Figures 1 to 13 In the universal noise measurement circuit shown in , the at least one circuit board is built into the shielding box 1 and is correspondingly connected to a plurality of connecting plugs arranged on the shielding box 1 .

[0085] The shell of the shielding box 1 and the several connecting connectors are all made of metal, and the shell of the shielding box 1 and at least one circuit board 1 are single-point grounded. In this way, the integrity of the shielding layer can be further guaranteed, thereby avoiding noise interference that may be caused by external magnetic field interference, which helps to improve the accuracy of measurement.

[0086] refer to Fig.15a , a first measurement port Output1 and a second measurement port Output2 are provided on the front side of the shell of the shielding box 1, a switch 11 and an indicator light (such as LED1 and LED2, wherein LED1 and LED2 correspond to the first indicator light and the second indicator light in the universal noise measurement circuit, respectively) corresponding to the first measurement port and the second measurement port, and a selection switch (such as switch 12, switch 13 and switch 14) corresponding to a plurality of different measurement ranges of the first measurement port. Exemplarily, the first measurement port Output1 corresponds to a noise frequency measurement range greater than 10 Hz, and the second measurement port Output2 corresponds to a noise frequency measurement range of 0.1 Hz to 10 Hz. Switch 12, switch 13 and switch 14 are used to select the noise frequency measurement ranges of 10 to 100 kHz, 10 to 1 MKHz and 10 to infinity, respectively.

[0087] Furthermore, in other embodiments of the present disclosure, the switch 12, the switch 13 and the switch 14 may also be integrated into a knob switch with different gears, or a push button switch with multi-level switching capability, which is not limited in the present invention.

[0088] It should be understood that the switch 11 corresponds to Fig.13 The sixth multiple-choice selection switch U23 in the embodiment, switches 12, 13 and 14 correspond to Fig.11 The first switch U20 in.

[0089] refer to Fig.15b On the rear side of the shielding box 1, a power switch 19, a pre-charging port, a pre-charging switch 15, a charging port, an external power supply area 18, an input port for the noise signal to be measured, an internal power supply / external power supply switch 16, and a power supply / charging switch 17 corresponding to the battery pack are arranged. Among them, the external power supply area 18 includes a first power supply area 181 and a second power supply area 182, and two power supply interfaces of different specifications are arranged in the first power supply area 181 and the second power supply area 182, respectively, to increase the versatility of the input connector.

[0090] Furthermore, the power switch 19 can be selected as a switch with an indicator light, which takes into account both the power indicator light and the switch function, thereby reducing the occupied panel area.

[0091] It should be understood that the above switches 16 and 17 correspond to Figure 2 The second switch 130 in the switch 15 corresponds to Figure 4 Meanwhile, in other embodiments of the present disclosure, the charging port and the external power supply area 18 may also be integrated as follows: Figure 2 An external power supply port in the invention is not limited to this.

[0092] As described above, the present invention performs multi-stage filtering and amplification on the input noise signal to be tested through a multi-stage filtering and amplification module, and simultaneously generates at least two intermediate signals to be tested with different cutoff frequencies in the process, thereby providing the possibility of simultaneously testing the noise signal with the test within the range of two different noise parameters (noise frequencies), and avoiding the test error caused by the change of the test environment and the test system. For the first of the at least two signals to be tested, after further filtering by the bandwidth buffer module and the low-pass filter module, a noise measurement channel with noise greater than the third cutoff frequency and a plurality of noise measurement channels with noise greater than the third cutoff frequency and less than the different cutoff frequencies of a plurality of low-pass filter units can be obtained respectively, and for the second of the at least two signals to be tested, after filtering by the bandpass filter, a noise measurement channel with noise greater than the fourth cutoff frequency and less than the third cutoff frequency can be obtained. Therefore, based on the above-mentioned multiple different noise measurement channels, the present disclosure can meet the filtering and amplification of all noise parameters based on one circuit, and thus can meet the noise measurement requirements for different chips and circuits (such as different operational amplifiers, LDOs and REFs), and has strong versatility.

[0093] On the other hand, the circuit disclosed in the present invention can also effectively filter out excess noise and interference from the background noise of the circuit through multi-level filtering during the noise measurement process, thereby ensuring the integrity of the input noise signal to be measured.

[0094] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0095] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A general noise measurement circuit, wherein: include: A first filtering and amplifying module receives a noise signal to be measured, and is used to perform a first-stage filtering and amplification on the noise signal to be measured; A second filtering and amplifying module is connected to the output end of the first filtering and amplifying module, and includes a plurality of filtering and amplifying units, each of which is used to perform a second-stage filtering and amplifying on the output signal of the first filtering and amplifying module based on different cutoff frequencies, wherein the plurality of filtering and amplifying units include a first filtering and amplifying unit and a second filtering and amplifying unit, the first filtering and amplifying unit is used to perform a second-stage filtering and amplifying on the output signal of the first filtering and amplifying module based on a first cutoff frequency, and the second filtering and amplifying unit is used to perform a second-stage filtering and amplifying on the output signal of the first filtering and amplifying module based on a second cutoff frequency; a third filtering and amplifying module, connected to the output end of the first filtering and amplifying unit, and configured to perform a third level of filtering and amplifying on the output signal of the first filtering and amplifying unit based on a third cutoff frequency; a fifth amplifying module, connected to the output end of the second filtering and amplifying unit, and configured to perform a third stage amplification on the output signal of the second filtering and amplifying unit; A bandwidth buffer module, connected to the output end of the third filtering and amplifying module, for buffering and outputting the output signal of the third filtering and amplifying module to provide a noise measurement channel with noise greater than the third cutoff frequency; A low-pass filtering module, comprising a plurality of low-pass filtering units with different cut-off frequencies, each of which is connected to the output end of the third filtering and amplifying module, and the low-pass filtering module is used to perform a fourth-stage filtering on the output signal of the third filtering and amplifying module to provide a plurality of noise measurement channels whose noise is greater than the third cut-off frequency and less than different cut-off frequencies of the plurality of low-pass filtering units; a bandpass filtering module connected to the output end of the fifth amplifying module, for performing a third-stage filtering on the output signal of the fifth amplifying module based on a third cutoff frequency and a fourth cutoff frequency, so as to provide a noise measurement channel with noise greater than the fourth cutoff frequency and less than the third cutoff frequency; and The power supply module is respectively connected to the first filter amplification module, the second filter amplification module, the third filter amplification module, the fifth amplification module, the bandwidth buffer module, the low-pass filter module and the band-pass filter module to provide a power supply voltage.

2. The universal noise measurement circuit according to claim 1, wherein: The universal noise measurement circuit also includes: a fourth high-pass filtering module, whose output end is connected to the first measurement port of the universal noise measurement circuit, and whose input end is respectively connected to the output ends of the bandwidth buffer module and the low-pass filtering module, for performing high-pass filtering on the output signals of the bandwidth buffer module and the low-pass filtering module respectively based on the third cutoff frequency; A fifth high-pass filtering module has an output end connected to the second measurement port of the universal noise measurement circuit and an input end connected to the output end of the band-pass filtering module, and is used to perform high-pass filtering on the output signal of the band-pass filtering module based on a fourth cutoff frequency.

3. The universal noise measurement circuit according to any one of claims 1 and 2, wherein: The universal noise measurement circuit also includes: The indication module includes a first indicator light and a second indicator light. The indication module is respectively connected to the output end of the third filtering and amplifying module and the output end of the fifth amplifying module, and is used to select the corresponding first indicator light and second indicator light to light up according to the output signals of the third filtering and amplifying module and the fifth amplifying module.

4. The universal noise measurement circuit according to claim 1, wherein: The first filtering and amplifying module comprises: A first high-pass filtering unit, used for performing a first-stage high-pass filtering on the input noise signal to be measured; A plurality of first amplifying units connected in parallel are connected to the output end of the first high-pass filtering unit and are used to differentially amplify the output signal of the first high-pass filtering unit.

5. The universal noise measurement circuit according to claim 4, wherein: The first high-pass filtering unit comprises: A number of capacitors connected in parallel; A plurality of resistors connected between the negative terminals of the plurality of capacitors and a ground terminal; A first triode, a collector connected to the negative terminals of the plurality of capacitors, a base connected to the ground terminal, and an emitter suspended; The second transistor has a base connected to the negative terminals of the plurality of capacitors, a collector connected to the ground terminal, and an emitter suspended. Wherein, the effective part of the plurality of resistors connected between the negative terminals of the plurality of capacitors and the ground terminal is adjustable.

6. The universal noise measurement circuit according to claim 5, wherein: The universal noise measurement circuit also includes: a pre-charging unit connected to the plurality of capacitors and configured to pre-charge the plurality of capacitors; Wherein, the plurality of capacitors are all low leakage current capacitors.

7. The universal noise measurement circuit according to claim 4, wherein: The first filtering and amplifying unit comprises: A plurality of second high-pass filtering units connected in parallel are connected one-to-one with the output ends of the plurality of first amplifying units connected in parallel, and are used to perform a second stage of high-pass filtering on the output signals of the plurality of first amplifying units connected in parallel based on a first filtering frequency; A second amplifying unit is connected to the output ends of the plurality of second high-pass filtering units connected in parallel, and is used to amplify the voltage of the output signals of the plurality of second high-pass filtering units connected in parallel, Wherein, the amplification factor of the second amplification unit is adjustable.

8. The universal noise measurement circuit according to claim 4, wherein: The second filtering and amplifying unit comprises: A plurality of third high-pass filtering units connected in parallel are connected one-to-one with the output ends of the plurality of first amplifying units connected in parallel, and are used to perform a second stage of high-pass filtering on the output signals of the plurality of first amplifying units connected in parallel based on a second filtering frequency; a third amplifying unit connected to the output ends of the plurality of third high-pass filtering units connected in parallel, and configured to amplify the voltage of the output signals of the plurality of third high-pass filtering units connected in parallel, Wherein, the amplification factor of the third amplification unit is adjustable.

9. The universal noise measurement circuit according to claim 7, wherein: The third filtering and amplifying module comprises: a fourth high-pass filtering unit, connected to the output end of the second amplifying unit, for performing a third-stage high-pass filtering on the output signal of the second amplifying unit; a fourth amplifying unit connected to the output end of the fourth high-pass filtering unit and configured to amplify the voltage of the output signal of the fourth high-pass filtering unit; Wherein, the amplification factor of the fourth amplification unit is adjustable.

10. The universal noise measurement circuit according to claim 1, wherein: Each of the low-pass filter units is a fourth-order low-pass filter, and the band-pass filter module is a fourth-order band-pass filter.

11. The universal noise measurement circuit according to claim 2, wherein: The universal noise measurement circuit also includes: A first switch is connected between the output end of the bandwidth buffer module and the input end of the fourth high-pass filter module, and between the output end of each low-pass filter unit and the input end of the fourth high-pass filter module. The multiple first switches are used to selectively connect the first measurement port with one of the multiple noise measurement channels corresponding to the bandwidth buffer module and the low-pass filter module.

12. The universal noise measurement circuit according to claim 1, wherein: The first cut-off frequency is greater than the second cut-off frequency, the third cut-off frequency is greater than or equal to the first cut-off frequency, and the fourth cut-off frequency is greater than or equal to the second cut-off frequency.

13. The universal noise measurement circuit according to claim 1, wherein: The power module includes: a battery pack, a charge and discharge protection circuit, a low voltage drop linear regulator and a second switch. The battery pack is connected to the first end of the second switch through the charge and discharge protection circuit; The external power supply port of the power module is connected to the second end of the second switch; The low voltage drop linear regulator is connected to the third end of the second switch and the output end of the power module respectively; The second switch is used to select an electrical connection between the external power supply port, the output end of the power module and two of the battery packs.

14. A general noise measuring device, wherein: include: Shielding box; At least one circuit board, on which the universal noise measurement circuit as described in any one of claims 1 to 13 is integrated, and the at least one circuit board is built into the shielding box and is correspondingly connected to a plurality of connecting connectors arranged on the shielding box.

15. The universal noise measuring device according to claim 14, wherein: The shielding box and the plurality of connecting connectors are all made of metal.

16. The universal noise measuring device according to any one of claims 14 and 15, wherein: The shell of the shielding box and the at least one circuit board are both single-point grounded.

Images