Voltage loop of power supply board card and power supply board card

Abstract

The utility model relates to a voltage loop of a power supply board card, the power supply board card and a testing machine, the voltage loop comprises a first voltage input end, a second voltage input end, a primary gain module, a secondary gain module and a voltage output end, and the primary gain module comprises an instrument amplifier U1 and a first voltage division network resistor unit; the first input end and the second input end are respectively used for connecting two ends of a to-be-tested device; the first input end of the instrument amplifier U1 is connected with the first voltage input end through the first voltage dividing network resistor unit, the second input end of the instrument amplifier U1 is connected with the second voltage input end, the output end of the instrument amplifier U1 is connected with the secondary gain module, and the secondary gain module is connected with the voltage output end. The instrument amplifier U1 with an excellent common-mode rejection index is adopted, the voltage at the two ends of the to-be-tested device is received and processed through the first voltage division network resistor unit, the common-mode rejection ratio is increased, the common-mode interference resistance of the power supply board card is improved, and the measurement precision of the power supply board card is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor testing technology, and in particular to a voltage ring of a power board and a power board. Background Art

[0002] Semiconductor automated testing refers to the use of automatic test equipment (ATE) to detect various parameter indicators of the device under test (DUT) to eliminate defective products to control the factory quality of semiconductor devices. The power board is used in semiconductor testing equipment to provide voltage or current excitation to the chip under test to achieve functions such as voltage and current measurement. The measurement accuracy is determined by the voltage loop module of the power board. In traditional power boards, the voltage loop module uses a large number of ordinary discrete resistors, which have low temperature drift performance, and the link itself has poor common mode interference resistance, which is easy to introduce interference and directly affect the measurement results. How to improve the measurement accuracy of the power board is an urgent problem to be solved. Utility Model Content

[0003] Based on this, it is necessary to provide a voltage ring of a power board, a power board and a test machine that can improve the measurement accuracy of the power board in order to solve the above problems.

[0004] In a first aspect, the present application provides a voltage loop of a power board, comprising a first voltage input terminal, a second voltage input terminal, a first-level gain module, a second-level gain module and a voltage output terminal, wherein the first-level gain module comprises an instrumentation amplifier U1 and a first voltage divider network resistor unit; the first voltage input terminal and the second voltage input terminal are respectively used to connect two ends of a device to be tested;

[0005] The first input terminal of the instrument amplifier U1 is connected to the first voltage input terminal through the first voltage divider network resistor unit, the second input terminal of the instrument amplifier U1 is connected to the second voltage input terminal, the output terminal of the instrument amplifier U1 is connected to the secondary gain module, and the secondary gain module is connected to the voltage output terminal.

[0006] In one embodiment, the first voltage divider network resistor unit is a voltage divider network resistor unit having a plurality of gain adjustment gears.

[0007] In one embodiment, the first voltage divider network resistor unit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a first gate switch component, the first end of the resistor R1 is connected to the first voltage input end, the second end of the resistor R1 is connected to the first end of the resistor R2 and the first gate switch component, the second end of the resistor R2 is connected to the first end of the resistor R3 and the first gate switch component, the second end of the resistor R3 is connected to the first end of the resistor R4 and the first gate switch component, the second end of the resistor R4 is connected to the second input end of the instrument amplifier U1, and the first gate switch component is connected to the first input end of the instrument amplifier U1.

[0008] In one embodiment, the first selection switch component includes a switch S1, a switch S2 and a switch S3, the first end of the switch S1 is connected to the first input end of the instrument amplifier U1, the second end of the switch S1 is connected to the second end of the resistor R1 and the first end of the resistor R2, the first end of the switch S2 is connected to the first input end of the instrument amplifier U1, the second end of the switch S2 is connected to the second end of the resistor R2 and the first end of the resistor R3, the first end of the switch S3 is connected to the first input end of the instrument amplifier U1, and the second end of the switch S3 is connected to the second end of the resistor R3 and the first end of the resistor R4.

[0009] In one embodiment, the secondary gain module includes an instrumentation amplifier U2 and a second voltage divider network resistor unit, the first input terminal of the instrumentation amplifier U2 is grounded, the second input terminal of the instrumentation amplifier U2 is connected to the second voltage divider network resistor unit, and the second voltage divider network resistor unit is connected to the output terminal of the instrumentation amplifier U1, the output terminal of the instrumentation amplifier U2 and the voltage output terminal.

[0010] In one embodiment, the second voltage divider network resistor unit is a voltage divider network resistor unit having a plurality of gain adjustment gears.

[0011] In one embodiment, the second voltage divider network resistor unit includes resistors R5, R6, R7, R8, R9 and a second gate switch component. The output end of the instrument amplifier U1 is connected to the second input end of the instrument amplifier U2 through the resistor R5. The first end of the resistor R6 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R6 is connected to the second gate switch component. The first end of the resistor R7 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R7 is connected to the second gate switch component. The first end of the resistor R8 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R8 is connected to the second gate switch component. The first end of the resistor R9 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R9 is connected to the second gate switch component. The second gate switch component connects the output end of the instrument amplifier U2 and the voltage output end.

[0012] In one embodiment, the second selection switch component includes a switch S4 and a switch S5, the static contact of the switch S4 is connected to the output end of the instrumentation amplifier U2, the moving contact of the switch S4 is respectively connected to the second end of the resistor R6, the second end of the resistor R7, the second end of the resistor R8 and the second end of the resistor R9, the static contact of the switch S5 is connected to the voltage output end, and the moving contact of the switch S5 is respectively connected to the second end of the resistor R6, the second end of the resistor R7, the second end of the resistor R8 and the second end of the resistor R9.

[0013] In one embodiment, the voltage loop further includes a common-phase follower T1 and a common-phase follower T2, the first voltage divider network resistor unit is connected to the first voltage input terminal through the common-phase follower T1, and the second input terminal of the instrumentation amplifier U1 is connected to the second voltage input terminal through the common-phase follower T2.

[0014] The second aspect of the present application provides a power supply board, including an error comparator, an integrator, a power amplifier module, a sampling module and the above-mentioned voltage loop; the error comparator, the integrator, the power amplifier module and the sampling module are connected in sequence, the sampling module is connected to one end of the device to be tested through a high-level detection line, the other end of the device to be tested is connected to a low-level detection line, and the voltage ring connects the high-level detection line, the low-level detection line and the error comparator.

[0015] A third aspect of the present application provides a testing machine, comprising the above-mentioned power board.

[0016] The voltage loop of the power supply card, the power supply card and the tester, the voltage loop includes a primary gain module and a secondary gain module, the primary gain module includes an instrument amplifier U1 and a first voltage divider network resistor unit, the first input end of the instrument amplifier U1 is connected to the first voltage input end through the first voltage divider network resistor unit, the second input end of the instrument amplifier U1 is connected to the second voltage input end, and the output end of the instrument amplifier U1 is connected to the secondary gain module. The instrument amplifier U1 with excellent common mode rejection index is used, and the voltage at both ends of the device to be tested is received and processed through the first voltage divider network resistor unit, so as to improve the common mode rejection ratio, improve the anti-common mode interference capability of the power supply card, and improve the measurement accuracy of the power supply card. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural block diagram of a voltage loop in one embodiment;

[0018] Figure 2 is a structural principle diagram of a voltage loop in one embodiment;

[0019] Figure 3 FIG. 4 is a structural block diagram of a power board in an embodiment. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0022] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0023] When used herein, the singular forms "a", "an", and "the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0024] In one embodiment, Figure 1 As shown, a voltage loop of a power board is provided, including a first voltage input terminal POGO_HS, a second voltage input terminal POGO_LS, a first-level gain module 110, a second-level gain module 120 and a voltage output terminal OUT, wherein the first-level gain module 110 includes an instrumentation amplifier U1 and a first voltage divider network resistor unit 112, and the first voltage input terminal POGO_HS and the second voltage input terminal POGO_LS are respectively used to connect the two ends of the device to be tested. The first input terminal of the instrumentation amplifier U1 is connected to the first voltage input terminal POGO_HS through the first voltage divider network resistor unit 112, the second input terminal of the instrumentation amplifier U1 is connected to the second voltage input terminal POGO_LS, the output terminal of the instrumentation amplifier U1 is connected to the second-level gain module 120, and the second-level gain module 120 is connected to the voltage output terminal OUT.

[0025] The two ends of the device under test are respectively connected to a high detection line HS and a low detection line LS, and the first voltage input terminal POGO_HS and the second voltage input terminal POGO_LS can be respectively connected to the high detection line HS and the low detection line LS to access the voltages at both ends of the device under test. The specific structure of the first voltage divider network resistor unit 112 is not unique, and can be a fixed voltage divider network resistor unit or a voltage divider network resistor unit with multiple gain adjustment gears. In one embodiment, Figure 2 As shown, the first voltage divider network resistor unit 112 includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a first gate switch component 1122, the first end of the resistor R1 is connected to the first voltage input terminal POGO_HS, the second end of the resistor R1 is connected to the first end of the resistor R2 and the first gate switch component 1122, the second end of the resistor R2 is connected to the first end of the resistor R3 and the first gate switch component 1122, the second end of the resistor R3 is connected to the first end of the resistor R4 and the first gate switch component 1122, the second end of the resistor R4 is connected to the second input end of the instrument amplifier U1, and the first gate switch component 1122 is connected to the first input end of the instrument amplifier U1. Specifically, the in-phase input terminal + of the instrument amplifier U1 can be used as the first input terminal, and the inverting input terminal - of the instrument amplifier U1 can be used as the second input terminal. The first gate switch component 1122 can be a multi-channel switching chip, or it can be composed of multiple discrete switching switches. The resistance values ​​of the resistors R1, R2, R3 and R4 are different from each other. According to actual needs, the first selection switch component 1122 can be controlled to switch channels and change the gain coefficient of the instrument amplifier U1, thereby adjusting the gain gear.

[0026] The voltage loop is placed inside the power board. The GND plane of the power board is far away from the reference GND of the device to be tested and passes through many paths. When the current flows through the GND plane, a voltage drop will be generated. This voltage drop will appear in the form of common-mode interference on the high-level detection line HS and the low-level detection line LS, affecting the detection accuracy of the voltage loop for the load voltage. Therefore, it is very important to improve the voltage loop's suppression index for common-mode interference.

[0027] like Figure 2 As shown, it is assumed that the high-end voltage connected to the first voltage input terminal POGO_HS is V1, the low-end voltage connected to the second voltage input terminal POGO_LS is V2, the gain of the instrument amplifier U1 is G, and the positive voltage on the non-inverting input terminal + is V3. The equivalent resistance between the non-inverting input terminal + of the instrument amplifier U1 and the first voltage input terminal POGO_HS is R11, and the equivalent resistance between the inverting input terminal - of the instrument amplifier U1 and the second voltage input terminal POGO_LS is R12. According to the common mode definition, the common mode voltage Vcm=(V1+V2) / 2, and according to the superposition theorem, V3=V2*(R11 / (R11+R12))+V1*(R12 / (R11+R12)). The output voltage V4 of the instrument amplifier U1=(V3-V2)*G, and the two formulas are combined to obtain V4=(V1-V2)*(R12 / (R11+R12))*G. It can be deduced from the formula that the output of the instrumentation amplifier U1 is related to the differential mode voltage, voltage division ratio, and gain, but has nothing to do with the common mode voltage. Therefore, the common mode rejection ratio can be increased, and the power supply board's ability to resist common mode interference can be improved.

[0028] Furthermore, the voltage loop also includes a common-phase follower T1 and a common-phase follower T2, the first voltage-dividing network resistor unit 112 is connected to the first voltage input terminal POGO_HS through the common-phase follower T1, and the second input terminal of the instrumentation amplifier U1 is connected to the second voltage input terminal POGO_LS through the common-phase follower T2. Specifically, the input terminal of the common-phase follower T1 is connected to the first voltage input terminal POGO_HS, the output terminal of the common-phase follower T1 is connected to the first end of the resistor R1, the input terminal of the common-phase follower T2 is connected to the second voltage input terminal POGO_LS, and the output terminal of the common-phase follower T2 is connected to the second input terminal of the instrumentation amplifier U1.

[0029] In one embodiment, the first gating switch component 1122 includes a switch S1, a switch S2, and a switch S3, wherein the first end of the switch S1 is connected to the first input end of the instrument amplifier U1, the second end of the switch S1 is connected to the second end of the resistor R1 and the first end of the resistor R2, the first end of the switch S2 is connected to the first input end of the instrument amplifier U1, the second end of the switch S2 is connected to the second end of the resistor R2 and the first end of the resistor R3, the first end of the switch S3 is connected to the first input end of the instrument amplifier U1, and the second end of the switch S3 is connected to the second end of the resistor R3 and the first end of the resistor R4. An external controller can be used to connect the switch S1, the switch S2, and the switch S3, and the switch S1, the switch S2, and the switch S3 are controlled to be turned on in three choices to change the gain gear. The voltage difference between V1 and V2, that is, the voltage difference between the high detection line HS and the low detection line LS, is the voltage on the device to be tested. Four resistors with different resistance values ​​are connected in series between V1 and V2. The voltage difference between V1 and V2 is reduced by a corresponding ratio after being selected by a voltage divider network and switches S1, S2, and S3 (three-in-one switches). This belongs to the first-stage gain and is sent to the instrument amplifier U1 through a differential input.

[0030] In one embodiment, continue to refer to Figure 2 The secondary gain module 120 includes an instrumentation amplifier U2 and a second voltage divider network resistor unit 122. The first input terminal of the instrumentation amplifier U2 is grounded, the second input terminal of the instrumentation amplifier U2 is connected to the second voltage divider network resistor unit 122, and the second voltage divider network resistor unit 122 is connected to the output terminal of the instrumentation amplifier U1, the output terminal of the instrumentation amplifier U2, and the voltage output terminal OUT. Similarly, the non-inverting input terminal + of the instrumentation amplifier U2 can be used as the first input terminal, and the inverting input terminal - of the instrumentation amplifier U2 can be used as the second input terminal.

[0031] Furthermore, the voltage loop also includes a common-phase follower T3, the input end of the common-phase follower T3 is connected to the second voltage-dividing network resistor unit 122, and the output end of the common-phase follower T3 is connected to the voltage output end OUT. The output of the instrumentation amplifier U1 is amplified by the instrumentation amplifier U2 in an inverting manner and then transmitted to the common-phase follower T3. Similarly, the second voltage-dividing network resistor unit 122 can be a fixed voltage-dividing network resistor unit, or a voltage-dividing network resistor unit with multiple gain adjustment gears, and a secondary gain gear adjustment is performed.

[0032] In one embodiment, Figure 2As shown, the second voltage divider network resistor unit 122 includes resistors R5, R6, R7, R8, R9 and a second gate switch component 1222. The output end of the instrument amplifier U1 is connected to the second input end of the instrument amplifier U2 through the resistor R5. The first end of the resistor R6 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R6 is connected to the second gate switch component 1222. The first end of the resistor R7 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R7 is connected to the second gate switch component 1222. The first end of the resistor R8 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R8 is connected to the second gate switch component 1222. The first end of the resistor R9 is connected to the second input end of the instrument amplifier U2, and the second end of the resistor R9 is connected to the second gate switch component 1222. The second gate switch component 1222 is connected to the output end of the instrument amplifier U2 and the voltage output end OUT. Among them, the second gate switch component 1222 can be a multi-channel switching chip, or it can be composed of multiple discrete switching switches. The resistance values ​​of resistors R6, R7, R8 and R9 are different from each other. According to actual needs, the second selection switch component 1222 can be controlled by an external controller to switch the connected resistors to change the gain coefficient of the instrument amplifier U2, thereby adjusting the gain gear.

[0033] Specifically, the second selection switch component 1222 includes a switch S4 and a switch S5, the static contact of the switch S4 is connected to the output end of the instrumentation amplifier U2, the moving contact of the switch S4 is respectively connected to the second end of the resistor R6, the second end of the resistor R7, the second end of the resistor R8 and the second end of the resistor R9, the static contact of the switch S5 is connected to the voltage output end OUT, and can be specifically connected to the voltage output end OUT through the in-phase follower T3, and the moving contact of the switch S5 is respectively connected to the second end of the resistor R6, the second end of the resistor R7, the second end of the resistor R8 and the second end of the resistor R9. By controlling the switch S4 and the switch S5 to select one of the four, one of the resistor R6, the resistor R7, the resistor R8 and the resistor R9 is selected to be connected to the output end of the instrumentation amplifier U2 and the in-phase follower T3, and the feedback resistor of the instrumentation amplifier U2 is switched to select the corresponding gain gear, which belongs to the second-stage gain.

[0034] The above combination of the first voltage-divider network resistor unit 112 and the second voltage-divider network resistor unit 122 is to achieve the expansion of the voltage range through a two-level circuit cascade. The two-level circuit cascade can expand more voltage ranges, and it can be achieved with only a small number of resistors. The resistors selected in the first voltage-divider network resistor unit 112 and the second voltage-divider network resistor unit 122 can be a resistor array or a single precision resistor. These two resistor schemes can also be designed as a stacked pad. A single resistor is selected in the development stage, and a customized resistor array is replaced in the mass production stage. This can reduce costs and achieve complementary advantages. In this embodiment, the resistors in the first voltage-divider network resistor unit 112 and the second voltage-divider network resistor unit 122 are designed as resistor arrays. Different resistors need to be matched for different voltage ranges, which ensures the relative temperature drift and accuracy between the resistors.

[0035] The voltage loop provided by the present application improves the common-mode rejection ratio through an instrumentation amplifier. The change of the resistor voltage divider coefficient only affects the gain of the differential mode voltage and has no effect on the common-mode voltage, so it does not affect the common-mode rejection capability. Simply by selecting an instrumentation amplifier with excellent common-mode rejection indicators, the common-mode rejection performance of the entire voltage loop can be improved, which is low-cost and easy to implement. In addition, by using a small number of resistors to divide the voltage, the resistor voltage divider coefficient can be changed by using a switching switch, thereby adapting to different voltage range inputs.

[0036] In one embodiment, Figure 3 As shown, a power supply card is also provided, including an error comparator 300, an integrator 400, a power amplifier module 500, a sampling module 600 and the above-mentioned voltage loop 100; the error comparator 300, the integrator 400, the power amplifier module 500 and the sampling module 600 are connected in sequence, the sampling module 600 is connected to one end of the device under test DUT through the high-level detection line HS, and the other end of the device under test DUT is connected to the low-level detection line LS, and the voltage loop 100 is connected to the high-level detection line HS, the low-level detection line LS and the error comparator 300. Among them, the error comparator 300 is connected to the voltage Vdac, and the sampling module 600 may include a sampling resistor. Further, the power supply card may also include a common-phase follower 200, and the voltage loop 100 is connected to the error comparator 300 through the common-phase follower 200.

[0037] The power supply card can specifically be a VI power supply card, which is used in the test machine to provide voltage or current excitation to the device under test DUT and perform voltage and current measurement and other functions. The VI power supply card can realize the FVMV (pressure measurement) function, and the accuracy of FVMV is determined by the voltage loop 100. The voltage loop 100 is the voltage feedback loop part of the entire link. Its function is to extract the output signal of the link and input it to the input end of the link error amplifier after processing, so that the entire loop forms a negative feedback. Among them, the feedback signal is taken from the voltage difference between the high detection line HS and the low detection line LS: V HS -VLS , and the proportional amplification is realized by the amplifier in the voltage loop 100. Assuming that the gain of the link is -A, when -A*(VHS-VLS)+Vdac=0, the output of the error comparator 300 is 0, the input of the integrator 400 is 0, the output of the integrator 400 is stable, and the voltage Vout output to the high-level detection line HS does not change. Therefore, after the feedback reaches a steady state, there is V HS -V LS =Vdac / A. That is: Vout = Vdac / A. By changing A, the measuring range of FV and MV can be extended.

[0038] In addition, the power board may further include a switch K and an analog-to-digital converter, wherein the switch K connects the voltage loop 100, the in-phase follower 200 and the analog-to-digital converter. First, the switch K is controlled to turn on the voltage loop 100 and the in-phase follower 200, and after the feedback reaches a steady state, the switch K is controlled to turn on the voltage loop 100 and the analog-to-digital converter, and the output of the voltage loop 100 is sent to the analog-to-digital converter for collection to obtain the load terminal voltage, thereby realizing the MV pressure measurement function.

[0039] In one embodiment, a testing machine is further provided, comprising the above-mentioned power board.

[0040] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A voltage ring of a power board, characterized in that: It includes a first voltage input terminal, a second voltage input terminal, a first-level gain module, a second-level gain module and a voltage output terminal, wherein the first-level gain module includes an instrumentation amplifier U1 and a first voltage divider network resistor unit; the first voltage input terminal and the second voltage input terminal are respectively used to connect two ends of the device to be tested; The first input terminal of the instrument amplifier U1 is connected to the first voltage input terminal through the first voltage divider network resistor unit, the second input terminal of the instrument amplifier U1 is connected to the second voltage input terminal, the output terminal of the instrument amplifier U1 is connected to the secondary gain module, and the secondary gain module is connected to the voltage output terminal.

2. The voltage ring according to claim 1, characterized in that: The first voltage-dividing network resistor unit is a voltage-dividing network resistor unit having a plurality of gain adjustment gears.

3. The voltage ring according to claim 2, characterized in that: The first voltage divider network resistor unit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a first gate switch component, wherein the first end of the resistor R1 is connected to the first voltage input end, the second end of the resistor R1 is connected to the first end of the resistor R2 and the first gate switch component, the second end of the resistor R2 is connected to the first end of the resistor R3 and the first gate switch component, the second end of the resistor R3 is connected to the first end of the resistor R4 and the first gate switch component, the second end of the resistor R4 is connected to the second input end of the instrument amplifier U1, and the first gate switch component is connected to the first input end of the instrument amplifier U1.

4. The voltage ring according to claim 3, characterized in that: The first selection switch component includes a switch S1, a switch S2 and a switch S3, wherein the first end of the switch S1 is connected to the first input end of the instrument amplifier U1, the second end of the switch S1 is connected to the second end of the resistor R1 and the first end of the resistor R2, the first end of the switch S2 is connected to the first input end of the instrument amplifier U1, the second end of the switch S2 is connected to the second end of the resistor R2 and the first end of the resistor R3, the first end of the switch S3 is connected to the first input end of the instrument amplifier U1, and the second end of the switch S3 is connected to the second end of the resistor R3 and the first end of the resistor R4.

5. The voltage ring according to claim 1, characterized in that: The secondary gain module includes an instrumentation amplifier U2 and a second voltage divider network resistor unit, wherein the first input terminal of the instrumentation amplifier U2 is grounded, the second input terminal of the instrumentation amplifier U2 is connected to the second voltage divider network resistor unit, and the second voltage divider network resistor unit is connected to the output terminal of the instrumentation amplifier U1, the output terminal of the instrumentation amplifier U2 and the voltage output terminal.

6. The voltage ring according to claim 5, characterized in that: The second voltage-dividing network resistor unit is a voltage-dividing network resistor unit having a plurality of gain adjustment gears.

7. The voltage ring according to claim 6, characterized in that: The second voltage divider network resistor unit includes resistor R5, resistor R6, resistor R7, resistor R8, resistor R9 and a second gate switch component. The output end of the instrument amplifier U1 is connected to the second input end of the instrument amplifier U2 through the resistor R5, the first end of the resistor R6 is connected to the second input end of the instrument amplifier U2, the second end of the resistor R6 is connected to the second gate switch component, the first end of the resistor R7 is connected to the second input end of the instrument amplifier U2, the second end of the resistor R7 is connected to the second gate switch component, the first end of the resistor R8 is connected to the second input end of the instrument amplifier U2, the second end of the resistor R8 is connected to the second gate switch component, the first end of the resistor R9 is connected to the second input end of the instrument amplifier U2, the second end of the resistor R9 is connected to the second gate switch component, and the second gate switch component is connected to the output end of the instrument amplifier U2 and the voltage output end.

8. The voltage ring according to claim 7, characterized in that: The second selection switch component includes a switch S4 and a switch S5, the static contact of the switch S4 is connected to the output end of the instrumentation amplifier U2, the moving contact of the switch S4 is respectively connected to the second end of the resistor R6, the second end of the resistor R7, the second end of the resistor R8 and the second end of the resistor R9, the static contact of the switch S5 is connected to the voltage output end, and the moving contact of the switch S5 is respectively connected to the second end of the resistor R6, the second end of the resistor R7, the second end of the resistor R8 and the second end of the resistor R9.

9. The voltage ring according to any one of claims 1 to 8, characterized in that: It also includes a common-phase follower T1 and a common-phase follower T2. The first voltage-dividing network resistor unit is connected to the first voltage input terminal through the common-phase follower T1. The second input terminal of the instrumentation amplifier U1 is connected to the second voltage input terminal through the common-phase follower T2.

10. A power board, characterized in that: It comprises an error comparator, an integrator, a power amplification module, a sampling module and a voltage loop as described in any one of claims 1 to 9; the error comparator, the integrator, the power amplification module and the sampling module are connected in sequence, the sampling module is connected to one end of the device to be tested through a high-level detection line, the other end of the device to be tested is connected to a low-level detection line, and the voltage loop connects the high-level detection line, the low-level detection line and the error comparator.

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