High-precision test signal output device and test machine

Abstract

The utility model relates to a high-precision test signal output device and a test machine, and the device comprises a plurality of signal processing circuits which comprise a DC processing circuit and an AC processing circuit; a first change-over switch and a second change-over switch; the resistance value of the direct current processing circuit is far greater than that of the first change-over switch and that of the second change-over switch; the resistance selection circuit comprises a third change-over switch, a first resistance circuit and a second resistance circuit; when the input signal is a direct current signal, the direct current processing circuit, the second change-over switch, the third change-over switch and the first resistance circuit are communicated to form a first voltage division circuit, and a test signal is output after the input signal is subjected to voltage division; when the input signal is an alternating current signal, the alternating current processing circuit, the second change-over switch, the third change-over switch and the second resistance circuit are communicated to form a second voltage division circuit, and a test signal is output after the input signal is subjected to voltage division. According to the invention, the drifting phenomenon of the output test signal when the input signal is a DC signal can be avoided.

Description

Technical Field

[0001] The present application relates to the field of chip testing, and in particular to a high-precision test signal output device and a test machine. Background Art

[0002] Chip testing refers to using the test machine to output test signals to detect various parameter indicators of the device under test, eliminating defective products to control the factory quality of semiconductor devices. The test machine includes a test signal output device for outputting test signals.

[0003] In the prior art, the test signal output device is usually equipped with a pair of switching switches and at least one signal processing circuit. There are two types of switching switches: mechanical relays and RF MEMS switches. The use of mechanical relays has the disadvantages of large size and pile line effect. The typical value of the on-resistance of the RF MEMS switch is 1.6 ohms. Although it does not have the disadvantages of mechanical relays, the resistance of the RF MEMS switch is unstable over a period of time, and there is a resistance drift of 1.4 ohms. In a 50 ohm attenuation circuit, the output DC test signal will drift, resulting in a reduction in the accuracy of the test signal. Utility Model Content

[0004] Based on this, it is necessary to provide a high-precision test signal output device and a test machine to address the above technical problems.

[0005] In a first aspect, an embodiment of the present utility model provides a high-precision test signal output device, the device comprising:

[0006] A plurality of signal processing circuits corresponding to different gears; each of the signal processing circuits comprises a DC processing circuit and an AC processing circuit;

[0007] A first switch connected to the input ends of the plurality of signal processing circuits, and a second switch connected to the output ends of the plurality of signal processing circuits, for selecting access to one of the signal processing circuits; the resistance of the DC processing circuit is much greater than the resistance of the first switch and the second switch;

[0008] a resistance selection circuit connected to the second switch, the resistance selection circuit comprising a third switch, a first resistance circuit and a second resistance circuit;

[0009] When the input signal is a DC signal, the DC processing circuit, the second switching switch, the third switching switch and the first resistance circuit are connected to form a first voltage divider circuit, which divides the input signal and outputs a test signal; when the input signal is an AC signal, the AC processing circuit, the second switching switch, the third switching switch and the second resistance circuit are connected to form a second voltage divider circuit, which divides the input signal and outputs a test signal.

[0010] In one embodiment, the DC processing circuit includes a first resistor connected between the first switch and the second switch.

[0011] In one embodiment, the AC processing circuit includes a first capacitor, an attenuation circuit, and a second capacitor connected in series between the first switch and the second switch.

[0012] In one embodiment, the attenuation circuit includes a second resistor, a third resistor and a fourth resistor, the second resistor is connected between the first capacitor and the second capacitor, one end of the third resistor is connected to the middle node between the second resistor and the first capacitor, the other end of the third resistor is connected to a common ground, one end of the fourth resistor is connected to the middle node between the second resistor and the second capacitor, and the other end of the fourth resistor is connected to a common ground.

[0013] In one embodiment, the first resistance circuit includes a fifth resistor connected between a switching end of the third switch and a common ground;

[0014] The second resistance circuit includes a sixth resistor connected between the other switching end of the third switch and a common ground.

[0015] In one embodiment, the device further comprises an isolation circuit connected to an intermediate node between the second switch and the resistance selection circuit.

[0016] In one embodiment, the device further comprises a voltage conversion circuit connected to the output end of the isolation circuit.

[0017] In one embodiment, the first switch, the second switch, and the third switch are all MEMS switches.

[0018] In a second aspect, an embodiment of the present utility model provides a high-precision test signal output device, the device comprising:

[0019] Signal processing circuit, including DC processing circuit and AC processing circuit;

[0020] A first switch connected to the input end of the signal processing circuit and a second switch connected to the output end of the signal processing circuit are used to control the access of the signal processing circuit; the resistance of the DC processing circuit is much greater than the resistance of the first switch and the second switch;

[0021] a resistance selection circuit connected to the second switch, the resistance selection circuit comprising a third switch, a first resistance circuit and a second resistance circuit;

[0022] When the input signal is a DC signal, the DC processing circuit, the second switching switch, the third switching switch and the first resistance circuit are connected to form a first voltage divider circuit, which divides the input signal and outputs a test signal; when the input signal is an AC signal, the AC processing circuit, the second switching switch, the third switching switch and the second resistance circuit are connected to form a second voltage divider circuit, which divides the input signal and outputs a test signal.

[0023] In a third aspect, an embodiment of the present utility model provides a testing machine, comprising the high-precision test signal output device as described in the first aspect or the second aspect.

[0024] Compared with the prior art, this technical solution has the following technical effects:

[0025] Since the resistance of the DC processing circuit is much larger than the resistance of the first switching switch and the second switching switch, the drift of the output test signal can be avoided when the input signal is a DC signal, thereby meeting the high precision requirement of the test machine when outputting DC signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a high-precision test signal output device in one embodiment of the utility model;

[0027] Figure 2 This is a connection diagram of a high-precision test signal output device in an exemplary embodiment of the utility model;

[0028] Figure 3 It is a schematic diagram of an output signal when the input signal is a DC signal in one embodiment of the utility model;

[0029] Figure 4 It is a schematic diagram of an output signal when the input signal is an AC signal in one embodiment of the utility model;

[0030] Figure 5 It is a structural schematic diagram of a high-precision test signal output device in another embodiment of the utility model.

[0031] Among them, 10, signal processing circuit; 110, DC processing circuit; 120, AC processing circuit; 20, first switching switch; 30, second switching switch; 40, resistance selection circuit; 410, third switching switch; 420, first resistance circuit; 430, second resistance circuit; 50, isolation circuit; 60, voltage conversion circuit. DETAILED DESCRIPTION

[0032] 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.

[0033] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0034] Reference to "embodiments" in this application means that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in multiple embodiments of the application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0035] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0036] like Figure 1 As shown, an embodiment of the present application proposes a high-precision test signal output device, including: a plurality of signal processing circuits 10 corresponding to different gears; each signal processing circuit 10 includes a DC processing circuit 110 and an AC processing circuit 120; a first switching switch 20 connected to the input end of the plurality of signal processing circuits 10, and a second switching switch 30 connected to the output end of the plurality of signal processing circuits 10, for selecting the access of one of the signal processing circuits 10; the resistance value of the DC processing circuit 110 is much greater than the resistance value of the first switching switch 20 and the second switching switch 30; the resistor connected to the second switching switch 30 The selection circuit 40 includes a third switching switch 410, a first resistance circuit 420 and a second resistance circuit 430; when the input signal is a DC signal, the DC processing circuit 110, the second switching switch 30, the third switching switch 410 and the first resistance circuit 420 are connected to form a first voltage divider circuit, which divides the input signal and outputs a test signal; when the input signal is an AC signal, the AC processing circuit 120, the second switching switch 30, the third switching switch 410 and the second resistance circuit 430 are connected to form a second voltage divider circuit, which divides the input signal and outputs a test signal.

[0037] Among them, the first switch 20, the second switch 30, and the third switch 410 are all MEMS switches. Compared with mechanical relays, their wiring circuits are simple and small in size, which is convenient for implementation in the high-density circuits of existing test machines. In addition, there is no stub effect, and the test machine does not have abnormal signal attenuation when used at high frequencies.

[0038] The number of the signal processing circuits 10 is at least two, and the corresponding switching gears are also at least two, for example, there are four gears: 0.75V / V, 0.5V / V, 0.375V / V, and 0.25V / V.

[0039] The first switch 20 and the second switch 30 are a pair of switches, each having a plurality of switching ends for selecting the access of the signal processing circuit 10 of the corresponding gear.

[0040] The high-precision test signal output device in this embodiment can realize multi-gear switching for both DC signal input and AC signal input. In addition, since the resistance of the DC processing circuit 110 is much greater than the resistance of the first switch 20 and the second switch 30, it can avoid the drift of the output test signal when the input signal is a DC signal, thereby meeting the high-precision requirement of the test machine when outputting a DC signal.

[0041] In some embodiments, the apparatus further includes an isolation circuit 50 connected to an intermediate node between the second switch 30 and the resistance selection circuit 40 .

[0042] The isolation circuit 50 is used to isolate the influence of the signal processing circuit 10 on other functional module circuits, thereby improving the accuracy of the test signal.

[0043] The isolation circuit 50 is, for example, a follower operational amplifier.

[0044] In some embodiments, the device further includes a voltage conversion circuit 60 connected to the output end of the isolation circuit 50 .

[0045] The voltage conversion circuit 60 may include a sixth resistor connected in series to the output terminal of the isolation circuit 50 to convert the current test signal into a voltage test signal.

[0046] Combine the following Figure 2 A high-precision test signal output device is described in detail as an exemplary embodiment.

[0047] In this example embodiment, the high-precision test signal output device includes four signal processing circuits 10, which can realize four gear switching of 0.75V / V, 0.5V / V, 0.375V / V, and 0.25V / V. Each signal processing circuit 10 includes a DC processing circuit 110 and an AC processing circuit 120.

[0048] In the signal processing circuit 10 corresponding to the 0.75V / V gear, its DC processing circuit 110 includes a resistor R1 connected between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2); its AC processing circuit 120 includes a capacitor C1, an attenuation circuit, and a capacitor C2 connected in series between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2).

[0049] In the signal processing circuit 10 corresponding to the 0.5V / V gear, its DC processing circuit 110 includes a resistor R2 connected between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2), and its AC processing circuit 120 includes a capacitor C3, an attenuation circuit, and a capacitor C4 connected in series between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2).

[0050] In the signal processing circuit 10 corresponding to the 0.375V / V gear, its DC processing circuit 110 includes a resistor R3 connected between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2), and its AC processing circuit 120 includes a capacitor C5, an attenuation circuit, and a capacitor C6 connected in series between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2).

[0051] In the signal processing circuit 10 corresponding to the 0.25V / V gear, its DC processing circuit 110 includes a resistor R4 connected between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2), and its AC processing circuit 120 includes a capacitor C7, an attenuation circuit, and a capacitor C8 connected in series between the first switching switch 20 (SP4T_1) and the second switching switch 30 (SP4T_2).

[0052] The attenuation circuit of each signal processing circuit 10 is, for example, a π attenuation network, which is -3dB, -6dB, -9dB, and -12dB respectively.

[0053] Taking the -6dB attenuation circuit as an example, it includes resistors R8, R9 and R10. Resistor R8 is connected between capacitors C3 and C4, one end of resistor R9 is connected to the middle node between resistor R8 and capacitor C3, and the other end of resistor R9 is connected to the common ground. One end of resistor R10 is connected to the middle node between resistor R8 and capacitor C4, and the other end of resistor R10 is connected to the common ground.

[0054] The structures of the attenuation circuits of -3dB, -9dB and -12dB are the same as that of the attenuation circuit of -6dB and will not be described in detail.

[0055] The capacitors in each AC processing circuit 120 play a role in DC isolation.

[0056] The resistance of each DC processing circuit 110 is much greater than the resistance of the first switch 20 (SP4T_1) and the second switch 30 (SP4T_2). The on-resistance of the first switch 20 (SP4T_1) and the second switch 30 (SP4T_2) is typically 1.6 ohms, the resistance of the resistor R1 is, for example, 414 ohms, the resistance of the resistor R2 is, for example, 1K ohms, the resistance of the resistor R3 is, for example, 1.9K ohms, and the resistance of the resistor R4 is, for example, 3K ohms.

[0057] Since the resistance of each DC processing circuit 110 is much greater than the resistance of the first switch 20 (SP4T_1) and the second switch 30 (SP4T_2), the drift of the output test signal can be avoided when the input signal is a DC signal, thereby improving the accuracy of the test signal.

[0058] The resistance of each DC processing circuit 110 is much greater than the equivalent resistance of the corresponding attenuation circuit. The resistance of the resistor R2 is, for example, 1K ohms, and the equivalent resistance of the -6 dB attenuation circuit is, for example, 50 ohms.

[0059] When the input signal is an AC signal, since the resistance of each DC processing circuit 110 is much greater than the equivalent resistance of the corresponding attenuation circuit, most of the energy of the input signal passes through the AC processing circuit 120 .

[0060] The resistor selection circuit 40 includes a third switch 410 (SP2T), a first resistor circuit 420, and a second resistor circuit 430. Specifically, the first resistor circuit 420 includes a fifth resistor R5 connected between one switching end of the third switch 410 (SP2T) and a common ground. The second resistor circuit 430 includes a sixth resistor R6 connected between the other switching end of the third switch 410 (SP2T) and a common ground.

[0061] The fifth resistor and the sixth resistor have different resistance values. The fifth resistor is, for example, 1K ohms, and the sixth resistor is, for example, 50 ohms.

[0062] The third switching switch 410 has two switching ends for selecting the access of the first resistance circuit 420 or the second resistance circuit 430. Specifically, when the input signal is a DC signal, the first resistance circuit 420 (resistor R5) is selected for access, and the DC processing circuit 110, the third switching switch 410 (SP2T) and the first resistance circuit 420 are connected to form a first voltage divider circuit. The middle node of the first voltage divider circuit is the output end of the test signal. When the input signal is an AC signal, the second resistance circuit 430 (resistor R6) is selected for access, and the AC processing circuit 120, the third switching switch 410 (SP2T) and the second resistance circuit 430 are connected to form a second voltage divider circuit, and the middle node of the second voltage divider circuit is the output end of the test signal.

[0063] The isolation circuit 50 uses a follower operational amplifier to isolate the influence of the signal processing circuit 10 on other functional module circuits, thereby improving the accuracy of the test signal.

[0064] The voltage conversion circuit 60 includes a resistor R7 connected in series to the output end of the isolation circuit 50 to convert the current test signal into a voltage test signal.

[0065] When the input signal is a DC signal and the 0.5V / V gear switching is required, the first switch 20 (SP4T_1) and the second switch 30 (SP4T_2) are controlled so that the DC processing circuit 110 corresponding to the 0.5V / V gear forms a path. Because the input signal is a DC signal, and the capacitors C3 and C4 play a role of DC isolation, the signal energy flows out of the second switch 30 (SP4T_2) after passing through the resistor R2 in the DC processing circuit 110; at the same time, the third switch 410 (SP2T) is controlled so that the resistor R5 in the first resistor circuit 420 is connected.

[0066] In this example embodiment, R2 = R5 = 1KΩ, so the input signal is attenuated to 0.5V / V after voltage division. Figure 3 As shown, since the resistance R2 is 1K ohms, which is much larger than the resistance drift of the switch of 1.4 ohms, the output test signal has almost no drift.

[0067] When the input signal is an AC signal and the 0.5V / V gear switching is required, the first switch 20 (SP4T_1) and the second switch 30 (SP4T_2) are controlled so that the -6dB attenuation network of the 0.5V / V gear forms a path. Since the resistor R2 is 1KΩ, which is much larger than the equivalent resistance of the -6dB attenuation network of 50 ohms, the signal energy will pass through the capacitor C3, enter the -6dB attenuation network, and then flow out of the second switch 30 (SP4T_2) after passing through the capacitor C4; at the same time, the third switch 410 (SP2T) is controlled so that the resistor R6 in the second resistor circuit 430 is connected.

[0068] like Figure 4 As shown, since the input and output resistances of the -6dB attenuation network are both 50 ohms, the AC signal energy is attenuated by 6dB and the voltage is attenuated by 0.5V / V. The AC signal can also meet the precise gear switching requirements at high frequencies.

[0069] An embodiment of the present application also provides a high-precision test signal output device, such as Figure 5 As shown, the device includes: a signal processing circuit 10, including a DC processing circuit 110 and an AC processing circuit 120; a first switch 20 connected to the input end of the signal processing circuit 10, and a second switch 30 connected to the output end of the signal processing circuit 10, for controlling the access of the signal processing circuit 10; the resistance of the DC processing circuit 110 is much greater than the resistance of the first switch 20 and the second switch 30; a resistor selection circuit 40 connected to the second switch 30, the resistor selection circuit 40 includes a third switch 410, a first resistor circuit 420 and a second resistor circuit 430; when the input signal is a DC signal, the DC processing circuit 110, the second switch 30, the third switch 410 and the first resistor circuit 420 are connected to form a first voltage divider circuit, and the input signal is divided and then a test signal is output; when the input signal is an AC signal, the AC processing circuit 120, the second switch 30, the third switch 410 and the second resistor circuit 430 are connected to form a second voltage divider circuit, and the input signal is divided and then a test signal is output.

[0070] The difference between this embodiment and the above-mentioned embodiments is that this high-precision test signal output device has only one signal processing circuit, and does not perform multiple gear switching outputs for the input signal, but only processes the input signal through one signal processing circuit and then outputs it.

[0071] In this embodiment, since the resistance of the DC processing circuit 110 is much larger than the resistance of the first switching switch 20 and the second switching switch 30, it is possible to avoid drift of the output test signal when the input signal is a DC signal, thereby achieving the high precision requirement of the test machine when outputting a DC signal.

[0072] In some embodiments, the apparatus further includes an isolation circuit 50 connected to an intermediate node between the second switch 30 and the resistance selection circuit 40 .

[0073] The isolation circuit 50 is used to isolate the influence of the signal processing circuit 10 on other functional module circuits, thereby improving the accuracy of the test signal.

[0074] The isolation circuit 50 is, for example, a follower operational amplifier.

[0075] In some embodiments, the device further includes a voltage conversion circuit 60 connected to the output end of the isolation circuit 50 .

[0076] The voltage conversion circuit 60 may include a sixth resistor connected in series to the output terminal of the isolation circuit 50 to convert the current test signal into a voltage test signal.

[0077] An embodiment of the present application further provides a testing machine, comprising the high-precision test signal output device in the above embodiment.

[0078] Since the test machine includes the high-precision test signal output device in the above embodiment, it can solve the same technical problem and achieve the same technical effect, which will not be described in detail here.

[0079] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above 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.

[0080] The above 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 high-precision test signal output device, characterized in that: The device comprises: A plurality of signal processing circuits corresponding to different gears; each of the signal processing circuits comprises a DC processing circuit and an AC processing circuit; A first switch connected to the input ends of the plurality of signal processing circuits, and a second switch connected to the output ends of the plurality of signal processing circuits, for selecting access to one of the signal processing circuits; the resistance of the DC processing circuit is much greater than the resistance of the first switch and the second switch; a resistance selection circuit connected to the second switch, the resistance selection circuit comprising a third switch, a first resistance circuit and a second resistance circuit; When the input signal is a DC signal, the DC processing circuit, the second switching switch, the third switching switch and the first resistance circuit are connected to form a first voltage divider circuit, which divides the input signal and outputs a test signal; when the input signal is an AC signal, the AC processing circuit, the second switching switch, the third switching switch and the second resistance circuit are connected to form a second voltage divider circuit, which divides the input signal and outputs a test signal.

2. The high-precision test signal output device according to claim 1, characterized in that: The DC processing circuit includes a first resistor connected between the first switch and the second switch.

3. The high-precision test signal output device according to claim 1, characterized in that: The AC processing circuit includes a first capacitor, an attenuation circuit, and a second capacitor connected in series between the first switch and the second switch.

4. The high-precision test signal output device according to claim 3, characterized in that: The attenuation circuit includes a second resistor, a third resistor and a fourth resistor, the second resistor is connected between the first capacitor and the second capacitor, one end of the third resistor is connected to the middle node between the second resistor and the first capacitor, the other end of the third resistor is connected to a common ground, one end of the fourth resistor is connected to the middle node between the second resistor and the second capacitor, and the other end of the fourth resistor is connected to a common ground.

5. The high-precision test signal output device according to claim 1, characterized in that: The first resistance circuit includes a fifth resistor connected between a switching end of the third switch and a common ground; The second resistance circuit includes a sixth resistor connected between the other switching end of the third switch and a common ground.

6. The high-precision test signal output device according to claim 1, characterized in that: The apparatus further includes an isolation circuit connected to an intermediate node between the second switch and the resistance selection circuit.

7. The high-precision test signal output device according to claim 6, characterized in that: The device also includes a voltage conversion circuit connected to the output terminal of the isolation circuit.

8. The high-precision test signal output device according to claim 1, characterized in that: The first switch, the second switch, and the third switch are all MEMS switches.

9. A high-precision test signal output device, characterized in that: The device comprises: Signal processing circuit, including DC processing circuit and AC processing circuit; A first switch connected to the input end of the signal processing circuit and a second switch connected to the output end of the signal processing circuit are used to control the access of the signal processing circuit; the resistance of the DC processing circuit is much greater than the resistance of the first switch and the second switch; a resistance selection circuit connected to the second switch, the resistance selection circuit comprising a third switch, a first resistance circuit and a second resistance circuit; When the input signal is a DC signal, the DC processing circuit, the second switching switch, the third switching switch and the first resistance circuit are connected to form a first voltage divider circuit, which divides the input signal and outputs a test signal; when the input signal is an AC signal, the AC processing circuit, the second switching switch, the third switching switch and the second resistance circuit are connected to form a second voltage divider circuit, which divides the input signal and outputs a test signal.

10. A testing machine, characterized in that: It comprises the high-precision test signal output device as described in any one of claims 1 to 9.

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