Measurement circuit and test device
Patent Information
- Application Number
- CN202510250688.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2026-09-04
AI Technical Summary
[0002]随着半导体技术和高制程加工工艺的发展，根据nm级晶圆加工的要求，以及新型封装技术等发展需要，需要用到皮安(pA)级乃至飞安(fA)级的高精密的电流测量；现有的测量电路中，包括有源测量模块、传输单元和被测器件，由于源测量模块和被测器件之间会设置传输单元，通过源测量模块将待测信号通过传输单元传输至被测器件，进一步地源测量模块可以采样流经了被测器件的待测信号以得到被测器件的电学参数，如流经被测器件的电流等，而由于在对被测器件进行测量时，无法将体积较大的源测量模块靠近被测器件设置，则传输单元需要很长，进而传输单元产生的噪声就会比较大，当流经被测器件的待测信号较小时，该较小的待测信号先通过传输单元传输至待测芯片，再传回源测量模块测量，由于传输单元的产生的噪声很大，则较小的待测信号可能甚至可能会被噪声淹没，进而使得源测量模块测得的通过被测器件的信号与真实值会有较大的差距，降低了测量电路的测量精度
[0005] This invention controls the ratio of the current flowing through the first conversion module to the current flowing through the second conversion module, thereby controlling the current gain of the preamplifier. In other words, the current of the second main signal input to the device under test (DUT) can be attenuated by the preamplifier according to the current gain, transmitting it to the DUT as a small current signal. Specifically, when measuring a small current flowing through the DUT, only the current gain of the preamplifier needs to be controlled to attenuate the current of the second main signal as needed and transmit it directly to the DUT, eliminating the need to transmit the small signal directly through a long transmission unit, thus avoiding noise interference. At this point, the current sampled by the source measurement module is actually the current in the first main signal, which is the current before attenuation, i.e., a large current. Transmitting it to the source measurement module through a long transmission unit would still result in a small current. By transmitting large signals, it is further possible to measure the current signal value in the first main signal using the source measurement module. Based on this current signal value and the current gain, the small current (actual current) flowing through the device under test can be obtained. Since all signals during transmission are large signals, noise interference experienced by small signals during transmission is avoided. In addition, the preamplifier can be placed between the source measurement module and the device under test, and closer to the device under test. The transmission distance between the preamplifier and the device under test is relatively short, so the leakage current generated between the preamplifier and the device under test is also relatively small. This further avoids noise interference during the measurement of small signals, ensuring that the actual current value flowing through the device under test obtained from the current gain of the preamplifier and the current measurement value is closer to the true value of the current flowing through the device under test. Therefore, the measurement accuracy of the measurement circuit is improved.
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Figure CN122690192A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-precision measurement, and in particular to a measurement circuit and testing equipment. Background Technology
[0002] With the development of semiconductor technology and advanced manufacturing processes, and based on the requirements of nanometer-level wafer fabrication and the development needs of new packaging technologies, high-precision current measurement at the picoampere (pA) and even femtoampere (fA) levels is required. Existing measurement circuits include an active measurement module, a transmission unit, and a device under test (DUT). A transmission unit is established between the active measurement module and the DUT. The active measurement module transmits the signal under test (SUT) to the DUT via the transmission unit. Furthermore, the active measurement module can sample the SUT signal flowing through the DUT to obtain the DUT's electrical parameters, such as the current flowing through the DUT. However, when measuring the device under test (DUT), it is impossible to place the large source measurement module close to the DUT. Therefore, the transmission unit needs to be very long, which leads to a large amount of noise generated by the transmission unit. When the test signal flowing through the DUT is small, the small test signal is first transmitted to the chip under test through the transmission unit and then transmitted back to the source measurement module for measurement. Due to the large amount of noise generated by the transmission unit, the small test signal may even be drowned out by the noise, which will cause a large difference between the signal measured by the source measurement module and the actual value, thus reducing the measurement accuracy of the measurement circuit. Summary of the Invention
[0003] The purpose of this invention is to provide a measurement circuit and testing equipment for reducing leakage current in the measurement circuit and improving measurement accuracy.
[0004] A measurement circuit, connected to a device under test (DUT), is used to perform tests on electrical signals from the DUT. The measurement circuit includes a source measurement module and a preamplifier. The preamplifier includes a first operational amplifier, a first conversion module, and a second conversion module. The current gain of the preamplifier is controlled by controlling the ratio between the current flowing through the first conversion module and the current flowing through the second conversion module. The source measurement module is connected to the non-inverting input of the first operational amplifier. A first conversion module is connected between the non-inverting input and output of the first operational amplifier. The output of the first operational amplifier is connected to the device under test (DUT) through a second conversion module, and the inverting input of the first operational amplifier is also connected to the DUT. The source measurement module outputs a first main signal, which is then connected to the non-inverting input of the first operational amplifier and the first conversion module, respectively. The second main signal obtained from the first main signal is transmitted to the device under test through the inverting input of the first operational amplifier. The source measurement module samples the signal output by the first conversion module of the preamplifier, and the source measurement module samples and measures the current signal value in the first main signal. Based on the current signal value and the current gain of the preamplifier, the actual current value flowing through the device under test is obtained.
[0005] This invention controls the ratio of the current flowing through the first conversion module to the current flowing through the second conversion module, thereby controlling the current gain of the preamplifier. In other words, the current of the second main signal input to the device under test (DUT) can be attenuated by the preamplifier according to the current gain, transmitting it to the DUT as a small current signal. Specifically, when measuring a small current flowing through the DUT, only the current gain of the preamplifier needs to be controlled to attenuate the current of the second main signal as needed and transmit it directly to the DUT, eliminating the need to transmit the small signal directly through a long transmission unit, thus avoiding noise interference. At this point, the current sampled by the source measurement module is actually the current in the first main signal, which is the current before attenuation, i.e., a large current. Transmitting it to the source measurement module through a long transmission unit would still result in a small current. By transmitting large signals, it is further possible to measure the current signal value in the first main signal using the source measurement module. Based on this current signal value and the current gain, the small current (actual current) flowing through the device under test can be obtained. Since all signals during transmission are large signals, noise interference experienced by small signals during transmission is avoided. In addition, the preamplifier can be placed between the source measurement module and the device under test, and closer to the device under test. The transmission distance between the preamplifier and the device under test is relatively short, so the leakage current generated between the preamplifier and the device under test is also relatively small. This further avoids noise interference during the measurement of small signals, ensuring that the actual current value flowing through the device under test obtained from the current gain of the preamplifier and the current measurement value is closer to the true value of the current flowing through the device under test. Therefore, the measurement accuracy of the measurement circuit is improved. Attached Figure Description
[0006] Figure 1 This is a schematic diagram of an existing measurement circuit; Figure 2 This is a schematic diagram of a measurement circuit according to the present disclosure; Figure 3 This is a schematic diagram of a measurement circuit according to an embodiment of the present disclosure; Figure 4 This is a schematic diagram of a measurement circuit according to another embodiment of the present disclosure; Figure 5 This is a schematic diagram of a measurement circuit according to another embodiment of the present disclosure; Figure 6 This is another schematic diagram of a measurement circuit according to yet another embodiment of the present disclosure; Figure 7 This is a schematic diagram of a floating power supply module; Figure 8 A schematic diagram of one embodiment of a floating power module; Figure 9 This is a schematic diagram of another embodiment of the floating power module; Figure 10 This is a schematic diagram of a measurement circuit including first and second preamplifiers, according to one embodiment of the present disclosure. Detailed Implementation
[0007] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.
[0008] Existing measurement circuits such as Figure 1 As shown, the system includes a source measurement module 01, a transmission unit 02, and a device under test (DUT) 03. The main signal output terminal and the sampling signal terminal of the source measurement module 01 are connected to the first terminal of the transmission unit 02, and the second terminal of the transmission unit 02 is connected to the DUT 03. The first main signal Force01 emitted by the main signal output terminal of the source measurement module 01 is transmitted to the DUT 03 via the transmission unit 02 to obtain the second main signal Force02. The sampling signal of the DUT 03 is defined as the second sampling signal Sense02, which is transmitted to the sampling signal terminal of the source measurement module 01 via the transmission unit 02 to obtain the first sampling signal Sense01. Since the source measurement module 01 cannot be directly close to the DUT 03, a relatively long transmission unit 02 is required to connect them. Therefore, there will be a large leakage current in the transmission unit 02. As a result, the signal flowing through the DUT 03 will have a large difference from the signal measured by the source measurement module 01, thereby reducing the measurement accuracy of the electrical parameters of the DUT 03 by the measurement circuit, such as reducing the measurement accuracy of the current flowing through the DUT 03.
[0009] To reduce leakage current in the measurement circuit and improve its measurement accuracy, this disclosure provides a measurement circuit, such as... Figure 2As shown, the circuit is connected to the device under test (DUT) 3 and used to perform tests on electrical signals from the DUT. The measurement circuit includes a source measurement module 1 and a preamplifier 2. The preamplifier 2 includes a first operational amplifier 201, a first conversion module 202, and a second conversion module 203. The current gain of the preamplifier 2 is controlled by controlling the ratio of the current flowing through the first conversion module 202 to the current flowing through the second conversion module 203. The source measurement module 1 is connected to the non-inverting input terminal + of the first operational amplifier 201. The first conversion module 202 is connected between the non-inverting input terminal + and the output terminal Out of the first operational amplifier 201. The output terminal Out of the first operational amplifier 201 is connected to the DUT 3 through the second conversion module 203, and the inverting input of the first operational amplifier 201 is connected to the DUT 3. Figure 2As can be seen, the first terminal of the first conversion module 202 is connected to the main signal output terminal of the source measurement module 1, and the sampling terminal of the source measurement module 1 is connected to the non-inverting input terminal + of the first operational amplifier 201, respectively. These three terminals share a common connection point, defined as the first connection point, with a voltage of Vin. The second terminal of the first conversion module 202 shares a common connection point with the output terminal Out of the first operational amplifier 201 and the first terminal of the second conversion module 203, defined as the second connection point, with a voltage of Vx. The second terminal of the second conversion module 203 shares a common connection point with the inverting input terminal - of the first operational amplifier 201 and the device under test 3, defined as the third connection point, with a voltage of Vo. The main signal output terminal of the source measurement module 1 outputs the first main signal Force1 with a voltage of Vin, which is then connected to the first operational amplifier. The non-inverting input terminal + of the amplifier 201 and the first terminal of the first conversion module 202 are connected to the inverting input terminal - of the first operational amplifier 201. The second main signal Force2 obtained from the first main signal Force1 is transmitted to the device under test 3. The source measurement module 1 collects the signal output by the first conversion module 202 of the preamplifier 2, and the source measurement module 1 samples and measures the current signal value in the first main signal Force1. Based on the current signal value and the current gain of the preamplifier 2, the actual current value flowing through the device under test 3 is obtained. The signal output by the first conversion module 202 of the preamplifier 2 is defined as the first sampling signal Sense1. The first sampling signal Sense1 is sent back to the source measurement module 1 to maintain the normal operation of the source measurement module 1, or the first sampling signal Sense1 can be measured to obtain the voltage under test of the device under test 3.Let I1 be the current flowing into the non-inverting input terminal (+) of the first operational amplifier 201; Iin1 be the current flowing between the first terminal of the first conversion module 202 and the first connection point; Iin be the current flowing between the first connection point and the source measurement module 1; I2 be the current flowing between the inverting input terminal (-) of the first operational amplifier 201 and the third connection point; Io1 be the current flowing between the second terminal of the second conversion module 203 and the third connection point; and Io be the current flowing between the third node and the device under test 3. Let GI be the current gain of the preamplifier 2. Therefore, GI = Io / Iin. Since the operational amplifier has… Due to the virtual short-circuit characteristic, Vo is approximately equal to Vin, therefore I2 is approximately 0, and Io and Io1 are approximately equal. In addition, since the operational amplifier has a virtual open-circuit characteristic, I1 is approximately 0, and Iin and Iin1 are approximately equal. Therefore, the equation GI=Io / Iin=Io1 / Iin1 is approximately true. Thus, by controlling the ratio between the current Iin1 flowing through the first conversion module 202 and the current Io1 flowing through the second conversion module 203, the current gain GI of the preamplifier 2 can be controlled. In other words, the value of Io can be calculated by measuring the value of Iin in the source measurement module 1 and then obtaining the value of GI. Figure 2 In the diagram, I_V+ is the first power supply terminal of the first operational amplifier 201, and I_V+ is the second power supply terminal of the first operational amplifier 201. Both are used to receive power signals so that the first operational amplifier 201 can work normally.
[0010] The measurement circuit disclosed in this embodiment connects the source measurement module 1 and the non-inverting input terminal + of the first operational amplifier 201. A first conversion module 202 is connected between the non-inverting input terminal + and the output terminal Out of the first operational amplifier 201. The output terminal Out of the first operational amplifier 201 is connected to the device under test 3 through a second conversion module 203, and the inverting input terminal - of the first operational amplifier 201 is connected between the second conversion module 203 and the device under test 3. Therefore, the first main signal Force1 output from the main signal output terminal of the source measurement module 1 is respectively connected to the non-inverting input terminal + of the first operational amplifier 201 and the first conversion module 202, and is converted through the inverting input terminal - of the first operational amplifier 201. The second main signal Force2, obtained from the first main signal Force1, is transmitted to the device under test (DUT) 3. The source measurement module 1 samples the signal output from the first conversion module 202 of the preamplifier 2 (i.e., the sampled signal) and transmits it to the source measurement module 1 to maintain its normal operation. The source measurement module 1 can also sample and measure the current signal value in the first main signal Force1. Based on the current signal value and the current gain GI of the preamplifier 2, the actual current flowing through the DUT 3 can be obtained. The actual current is generated by the first main signal after current attenuation as it flows through the DUT 3. This actual current can be a small current. Since the current Iin1 flowing through the first conversion module 202 and the control... The ratio between the currents Io1 flowing through the second conversion module 203 is used to control the current gain GI of the preamplifier 2. This means that the current of the second main signal Force2 entering the device under test (DUT) 3 can be attenuated by the preamplifier 2 according to the current gain GI, transmitting it as a small current signal to the DUT 3. Therefore, when measuring the small current (Io) flowing through the DUT 3, it is only necessary to control the current gain GI of the preamplifier 2 to attenuate the current of the second main signal Force2 as needed and transmit it directly to the DUT 3. This avoids the need to transmit the small signal directly through a long transmission unit to the DUT 3, which would cause noise interference. At this time, the current sampled by the source measurement module 1 is actually the first main signal F... The current signal in orce1, which is a large current signal, is transmitted to the source measurement module 1 through a relatively long transmission unit, still as a large signal. Furthermore, the current flowing through the device under test (DUT) 3, Io, can be obtained simply from the current signal Iin measured by the source measurement module 1. Since all signals transmitted are large, noise interference experienced by small signals during transmission is avoided. In addition, the preamplifier 2 can be positioned between the source measurement module 1 and the DUT 3, and closer to the DUT 3, resulting in a shorter transmission distance. Therefore, the leakage current between the preamplifier 2 and the DUT 3 is also relatively small, further avoiding noise interference during small signal measurements.This ensures that the current flowing through the device under test (DUT) 3, obtained from the current gain GI of preamplifier 2 and the current signal Iin of source measurement module 1, is closer to the true value of the current flowing through DUT 3, thus improving the measurement accuracy of the measurement circuit.
[0011] In some embodiments, such as Figure 3 As shown, the first conversion module 202 includes a first resistor 2021, and the second conversion module 203 includes a second resistor 2031. The first resistor 2021 is connected between the non-inverting input terminal + and the output terminal Out of the first operational amplifier 201, and the second resistor 2031 is connected between the output terminal Out of the first operational amplifier 201 and the device under test 3. By controlling the resistance values of the first resistor 2021 and the second resistor 2031, the ratio between the current Iin1 flowing through the first conversion module 202 and the current Io1 flowing through the second conversion module 203 is controlled, thereby controlling the current gain GI of the preamplifier 2. Figure 3 In this context, Iin1 = (Vin - Vx) / R1, Io1 = (Vx - Vo) / R2. Since Vin and Vo are approximately equal, in this embodiment, Vin and Vo can be considered equal. Therefore, Io1 = -((Vin - Vx) / R2). GI = Io / Iin = Io1 / Iin1 = -R2 / R1, In the formula, R1 is the resistance value of the first resistor 2021, and R2 is the resistance value of the second resistor 2031. Therefore, given the resistance values of the first resistor 2021 and the second resistor 2031, and based on the current signal Iin measured by the source measurement module 1, the current Io flowing through the device under test 3 can be calculated. In addition, to control the current gain, the value of the first resistor 2021 or the second resistor 2031 can be adjusted. This provides a simpler and easier-to-operate control method for measuring small currents, such as picoampere-level or even femtoampere-level currents. The first resistor 2021 and the second resistor 2031 can be other resistors with variable resistance values, such as sliding rheostats.
[0012] In some embodiments, such as Figure 4As shown, the first conversion module 202 includes a second operational amplifier 2023 and a third resistor 2022, and the second conversion module 203 includes a fourth resistor 2032. The non-inverting input terminal + of the second operational amplifier 2023 is connected to the output terminal Out of the first operational amplifier 201, and the inverting input terminal - of the second operational amplifier 2023 is connected to the output terminal Out of the second operational amplifier 2023. The output terminal Out of the second operational amplifier 2023 is connected to the non-inverting input terminal + of the first operational amplifier 201 through the third resistor 2022. That is, the non-inverting input terminal + is connected to the first end of the third resistor 2022, and the second end of the third resistor 2022 is connected to the second operational amplifier... The output terminal Out of the first operational amplifier 2023 is connected to the inverting input terminal of the second operational amplifier 2023; the output terminal Out of the first operational amplifier 201 is connected to the device under test 3 through the fourth resistor 2032, that is, the output terminal Out of the first operational amplifier 201 is connected to the first end of the fourth resistor 2032, and the second end of the fourth resistor 2032 is connected to both the inverting input terminal of the first operational amplifier 201 and the device under test 3, thereby controlling the resistance values of the third resistor 2022 and the fourth resistor 2032 to control the ratio between the current flowing through the first conversion module 202 and the current flowing through the second conversion module 203, and thus controlling the current gain GI of the preamplifier 2. Figure 4 In the given information, Iin1 = (Vin - Vd) / R3, Io1 = (Vx - Vo) / R4. Since Vd and Vx are approximately equal, and Vin and Vo are approximately equal, in this embodiment, Vin, Vo, and Vd can be considered equal. Therefore, Iin1 = (Vin - Vx) / R3, Io1 = -(Vin - Vx) / R4, where Vd is the voltage at the connection point formed by the third resistor 2022, the output terminal Out of the second operational amplifier 2023, and the inverting input terminal - of the second operational amplifier 2023. GI = Io / Iin = Io1 / Iin1 = -R4 / R3, In the formula, R3 is the resistance value of the third resistor 2022, and R4 is the resistance value of the fourth resistor 2032. Therefore, given the resistance values of the third resistor 2022 and the fourth resistor 2032, and based on the current signal Iin from the source measurement module 1, the current Io flowing through the device under test 3 can be calculated. Furthermore, to control the current gain GI, the value of either the third resistor 2022 or the fourth resistor 2032 can be adjusted. This provides a simpler and easier-to-operate control method for measuring small currents, such as picoampere-level or even femtoampere-level currents. The third resistor 2022 and the fourth resistor 2032 can be other variable resistors such as sliding rheostats. The purpose of introducing the second operational amplifier 2023 into the first conversion module 202 is to isolate the first main signal Force1 and the second main signal Force2, thereby reducing their mutual influence and further improving the measurement accuracy of the measurement circuit.
[0013] In some embodiments, such as Figure 5 and Figure 6 As shown, the first conversion module 202 includes a fifth resistor 2024, an amplification module 2025, and a third operational amplifier 2026. The second conversion module 203 includes a sixth resistor 2033. The first input terminal of the amplification module 2025 is connected to a signal equal to the voltage of the first main signal Force1. The second input terminal of the amplification module 2025 is connected to the output terminal Out of the third operational amplifier 2026. The output terminal of the amplification module 2025 is connected to the non-inverting input terminal + of the first operational amplifier 201 through the fifth resistor 2024. That is, the output terminal of the amplification module 2025 is connected to the second terminal of the fifth resistor 2024, and the first terminal of the fifth resistor 2024 is connected to the non-inverting input terminal + of the first operational amplifier 201. In fact, it can also be described that the first terminal of the fifth resistor 2024 is connected to the main signal output terminal of the source measurement module 1, the sampling terminal of the source measurement module 1, and... The non-inverting input terminal + of the first operational amplifier 201 is connected, the non-inverting input terminal + of the third operational amplifier 2026 is connected to the output terminal Out of the first operational amplifier 201, and the inverting input terminal - of the third operational amplifier 2026 is connected to the output terminal Out of the third operational amplifier 2026. The output terminal Out of the first operational amplifier 201 is connected to the device under test 3 through the sixth resistor 2033. That is, the output terminal Out of the first operational amplifier 201 is connected to the first end of the sixth resistor 2033, and the second end of the sixth resistor 2033 is connected to the inverting input terminal - of the first operational amplifier 201 and the device under test 3, respectively. The resistance values of the fifth resistor 2024 and the sixth resistor 2033 are controlled to control the ratio between the current flowing through the first conversion module 202 and the current flowing through the second conversion module 203, thereby controlling the current gain GI of the preamplifier 2.
[0014] In one specific implementation, such as Figure 5As shown, the first input terminal of the amplification module 2025 is connected between the non-inverting input terminal + of the first operational amplifier 201 and the fifth resistor 2024, so that the non-inverting input terminal + of the amplification module 2025 receives a signal with a voltage equal to that of the first main signal Force1; or, as shown... Figure 6 As shown, the first input terminal of the amplification module 2025 is connected between the inverting input terminal of the first operational amplifier 201 and the device under test 3, so that the first input terminal of the amplification module 2025 receives a signal with a voltage equal to that of the first main signal Force1. In this embodiment, the amplification module 2025 is introduced to ensure that the polarity of the current signal Iin from the source measurement module 1 is the same as the polarity of the current Io flowing through the device under test 3, thereby obtaining a positive current gain. This makes it easier to calculate the value of the current Io flowing through the device under test 3 based on the value of the current signal Iin. Further details can be found as follows... Figure 5 and Figure 6 As shown, the specific structure of the amplification module 2025 includes a sixth operational amplifier 20251, a first amplification resistor 20252, and a second amplification resistor 20253. The first terminal of the first amplification resistor 20252 is connected to the output terminal of the sixth operational amplifier 20251. The second terminal of the first amplification resistor 20252 is connected to both the inverting input terminal of the sixth operational amplifier 20251 and the first terminal of the second amplification resistor 20253. The second terminal of the second amplification resistor 20253 is connected to the output terminal of the third operational amplifier 2026. The sixth operational amplifier 20251... The output terminal of 51 serves as the output terminal of the amplification module 2025. The non-inverting input terminal + of the sixth operational amplifier 20251 serves as the first input terminal of the amplification module 2025, and the inverting input terminal - of the sixth operational amplifier 20251 serves as the second input terminal of the amplification module 2025. The resistance values of the first amplification resistor 20252 and the second amplification resistor 20253 are equal in this embodiment, but they can also be unequal. The current flowing into the second terminal of the fifth resistor 2024 is defined as Iin2, and the current flowing out from the first terminal of the first amplification resistor 20252 is defined as Id. Additionally, [the following is defined in the original text]. Figure 5 The current flowing into the non-inverting input terminal + of the sixth operational amplifier 20251 is I3. Figure 6 The current flowing into the non-inverting input (+) of the sixth operational amplifier 20251 is I5, and the current flowing into the inverting input (-) is I4. Figure 5In the diagram, Iin2 = (Vin - Vd0) / R5, Iin1 = Iin2 + I3, Io1 = (Vx - Vo) / R6. Because the operational amplifier has a virtual short-circuit characteristic, the voltage at the non-inverting input (+) and the voltage at the inverting input (-) of the sixth operational amplifier 20251 are both Vin, and Vin is approximately equal to Vo. In this embodiment, Vin and Vo can be considered equal. Because the operational amplifier has a virtual open-circuit characteristic, I3 and I4 are both approximately 0. Therefore, Iin1 = Iin2 = (Vin - Vd0) / R3. Also, because the first amplification resistor 2025... Since the resistance values of the first amplifying resistor 20252 and the second amplifying resistor 20253 are equal, and I4 is approximately 0, the voltages across the first amplifying resistor 20252 and the second amplifying resistor 20253 are approximately equal. In this embodiment, they can be considered equal. Therefore, Vd0 = 2Vin - Vx, and Iin1 = (Vx - Vin) / R5, Io1 = (Vin - Vx) / R6, where Vd0 is the voltage at the connection point formed by the fifth resistor 2024, the output terminal Out of the sixth operational amplifier 20251, and the inverting input terminal - of the sixth operational amplifier 20251. GI = Io / Iin = Io1 / Iin1 = R6 / R5 In the formula, R5 is the resistance value of the fifth resistor 2024, and R6 is the resistance value of the sixth resistor 2033. Therefore, given the resistance values of the fifth resistor 2024 and the sixth resistor 2033, and based on the current signal Iin from the source measurement module 1, the current Io flowing through the device under test 3 can be calculated. Furthermore, current gain control can be achieved by adjusting the values of the fifth resistor 2024 or the sixth resistor 2033. This provides a simpler and easier-to-operate control method for measuring small currents, such as picoampere-level or even femtoampere-level currents. The fifth resistor 2024 and the sixth resistor 2033 can be other variable resistors such as sliding rheostats. Figure 6 In this equation, Iin1 is equal to Iin2, I5 is approximately 0, and I2 is approximately 0. Therefore, Io1 and Io are approximately equal, and thus we get GI = Io / Iin = Io1 / Iin1 = R6 / R5.
[0015] In some embodiments, the protection signal output terminal of the source measurement module 1 outputs a first protection signal Guard1. The voltage of the first protection signal Guard1 is equal to the voltage of the first main signal Force1. The first protection signal Guard1 is used to protect the preamplifier 2. In addition, the first protection signal Guard1 can also be transmitted to the device under test 3 to protect the device under test 3.
[0016] In some embodiments, such as Figure 7As shown, the measurement circuit also includes a floating power supply module 4. The floating power supply module 4 is used to generate a floating signal FGND based on the reference signal Vref, and then generate a first floating power supply signal VF+ and a second floating power supply signal VF- using the floating signal FGND as a reference. The first floating power supply signal VF+ and the second floating power supply signal VF- are output to the preamplifier. The first floating power supply signal VF+ and the second floating power supply signal VF- are symmetrical about the reference signal Vref. The reference signal Vref is either the first main signal Force1 or the first protection signal Guard1.
[0017] The measurement circuit also includes a floating power supply module 4. The floating power supply module 4 has ports including a first external power signal input terminal I_VH+, a second external power signal input terminal I_VH-, a reference signal input terminal I_Vref, a first floating power signal output terminal O_VF+, a second floating power signal output terminal O_VF-, and a floating signal output terminal O_FGND. The floating power supply module 4 generates a floating signal FGND based on the reference signal Vref, then uses the floating signal FGND as a reference to generate a first floating power signal VF+ and a second floating power signal VF-, and outputs the first floating power signal VF+ to the reference signal output terminal O_VF+. The first operational amplifier 201 has a first power supply terminal I_V+, and outputs a second floating power signal VF- to the first power supply terminal I_V- of the first operational amplifier 201 through the second floating power signal output terminal O_VF-. The floating signal FGND can be used as a second protection signal Guard2 to be output from the floating signal output terminal O_FGND to the device under test 3 to protect the device under test 3. The first floating power signal VF+ and the second floating power signal VF- are symmetrical about the reference signal Vref, that is, the difference between the first floating power signal VF+ and the reference signal Vref is equal to the difference between the second floating power signal VF- and the reference signal Vref, but with opposite signs.
[0018] In one embodiment, such as Figure 8As shown, the internal components of the floating power module 4 also include a fourth operational amplifier 411, a first power supply circuit 409, and a second power supply circuit 410. The inverting input terminal - of the fourth operational amplifier 411 is connected to its output terminal Out. The positive input terminal In+ of the first power supply circuit 409 serves as the first external power signal input terminal I_VH+ and is connected to the first external power supply. The negative input terminal In- of the second power supply circuit 410 serves as the second external power signal input terminal I_VH- and is connected to the second external power supply. The non-inverting input terminal + of the fourth operational amplifier 411 is connected to a reference signal Vref. The fourth operational amplifier 411 generates a floating signal FGND based on the reference signal Vref and outputs it from its output terminal Out to the negative output terminal Out- of the first power supply circuit 409 and the positive output terminal Out+ of the second power supply circuit 410. The first floating power signal VF+ generated by the first power supply circuit 409 with reference to the floating signal FGND is output from its positive output terminal Out+ to the preamplifier 2. The second power supply circuit... The second floating power signal VF-, generated by the reference floating signal FGND, is output from the negative output terminal Out- of the second power circuit 410 to the preamplifier 2. The output terminal Out of the fourth operational amplifier 411 serves as the floating signal output terminal O_FGND of the floating power module 4, which is output as the floating signal FGND of the second protection signal Guard2 to the device under test 3 to protect the device under test 3. The negative input terminal In- of the first power circuit 409 and the positive input terminal In+ of the second power circuit 410 together serve as the analog ground signal receiver I-AGND, connected to the analog ground signal AGND as a potential reference point. The first power circuit 409 and the second power circuit 410 are isolated power circuits. The isolated power circuit can effectively isolate the input signal and the output signal, so that the input signal and the output signal can refer to different reference ground signals. In particular, in this embodiment, both the first floating power signal VF+ and the second floating power signal VF- can refer to the floating signal FGND, which can be set as required.
[0019] In one implementation, such as Figure 9As shown, the internal components of the floating power supply module 4 include a fifth operational amplifier 408, a first transistor 406, a second transistor 407, a seventh resistor 401, an eighth resistor 402, a ninth resistor 405, a first Zener diode 403, and a second Zener diode 404. The inverting input terminal of the fifth operational amplifier 408 is connected to its output terminal Out. The first terminal of the seventh resistor 401 and the collector of the first transistor 406 together serve as the first external power supply signal input terminal I_VH+, which is connected to the first external power supply. The second terminal of the seventh resistor 401 is connected to the first Zener diode 404. The negative terminal of the first Zener diode 403 is connected to the negative terminal of the second Zener diode 404 and simultaneously connected to one end of the ninth resistor 405. The other end of the ninth resistor 405 is connected to the output terminal of the fifth operational amplifier 408. The positive terminal of the second Zener diode 404 is connected to the second end of the eighth resistor 402. The first end of the eighth resistor 402 and the collector of the second transistor 407 together serve as the second external power supply signal input terminal I_VH-, connected to the second external power supply. The base of the first transistor 406 is connected to the second end of the seventh resistor 401. The emitter of the first transistor 406 is connected to the fifth operational amplifier 408. The first power supply terminal I_V+ of operational amplifier 408 is connected. The base of the second transistor 407 is connected to the second terminal of the eighth resistor 402. The emitter of the first transistor 406 is connected to the second power supply terminal I_V- of the fifth operational amplifier 408. The non-inverting input terminal + of the fifth operational amplifier 408 is used as the reference signal input terminal I_Vref and connected to the reference signal Vref. The fifth operational amplifier 408 generates a floating signal FGND based on the reference signal Vref and outputs the floating signal FGND through the ninth resistor 405. The first Zener diode 403 generates the first Zener diode according to the floating signal FGND. The control voltage of transistor 406 is used to control the opening of the first transistor 406 so that the first transistor 406 outputs a first floating power supply VF+ through its collector. Similarly, the second Zener diode 404 generates a control voltage for the second transistor 407 according to the floating signal FGND, so as to control the opening of the second transistor 407 so that the second transistor 407 outputs a second floating power supply VF- through its collector. At the same time, the first floating power supply signal VF+ and the second floating power supply signal VF- are also used to maintain the operating power supply of the fifth operational amplifier 408 to ensure the stable operation of the fifth operational amplifier 408.In this configuration, the first transistor 406 is an NPN transistor. The seventh resistor 401 divides the first external power supply signal to ensure that the voltage at the base (b) of the first transistor 406 is lower than the voltage at the collector (c), allowing the first transistor 406 to conduct normally. The second transistor 407 is a PNP transistor. The eighth resistor 402 divides the second external power supply signal to ensure that the voltage at the base (b) of the second transistor 407 is lower than the voltage at the collector (c), allowing the second transistor 407 to conduct normally. Additionally, the ninth resistor 405, the first Zener diode 403, and the second Zener diode 404 all serve to stabilize the floating signal FGND output from the floating signal output terminal O_FGND within a certain range. It should be noted that... Figure 8 and Figure 9 The illustrated embodiment is for illustrative purposes only. The floating power module 4 can adopt other structures, as long as it can be used to provide a floating power signal to the preamplifier so that the preamplifier can operate in the floating power domain.
[0020] In some embodiments, there are two preamplifiers 2. One preamplifier 21 has its first operational amplifier 201 output terminal Out connected to the first terminal of the device under test (DUT) 3 via a second conversion module 203, and its inverting input terminal connected to the first terminal of the DUT 3. The other preamplifier 2 has its first operational amplifier 201 output terminal Out connected to the second terminal of the DUT 3 via a second conversion module 203, and its inverting input terminal connected to the second terminal of the DUT 3. Additionally, the measurement circuit may include a first transmission unit 5, a second transmission unit 6, and a test fixture 7. The first transmission unit 5 and the second transmission unit 6... Unit 6 is used to transmit various signals, and test fixture 7 is used to fix the device under test 3. The main signal output from another main signal output terminal of the source measurement module 1 is defined as the third main signal Force3, and the main signal transmitted to the second terminal of the device under test 3 is defined as the fourth main signal Force4. The signal sampled by another sampling terminal of the source measurement module 1 is the second sampling signal Sense2. VH+ represents the first power supply signal received by the preamplifier 2, and VH- represents the second power supply signal received by the preamplifier 2. The function of the other preamplifier 2 is to provide a return path for the first main signal Force1. Therefore, the third main signal can be the reference ground signal, that is... Figure 10 The analog grounding signal AGND can also be a low-level signal to ensure that the first main signal Force1 is output from the source measurement module 1 and smoothly input back into the source measurement module 1. Additionally... Figure 10 The term "Control" refers to the control signal, which can be an external control command used to control the resistance values of the first resistor 2021, the second resistor 2031, the third resistor 2022, the fourth resistor 2032, the fifth resistor 2024, or the sixth resistor 2033, in order to control the current gain GI of the preamplifier 2.
[0021] The aforementioned source measurement module 1 can be a source measurement unit (SMU) and a parameter measurement unit (PMU), and all the voltages mentioned above are obtained based on the same potential reference signal. The potential reference signal can be an analog ground signal or other signals, depending on actual needs.
[0022] In addition, the present invention also provides a testing device, which includes multiple test channels, each of which includes the measurement circuit described in any of the above embodiments. Furthermore, it should be noted that the source-to-measure modulus module preamplifiers in the measurement circuit can be connected using a transmission unit, which can be a cable or a PCB (Printed Circuit Board), etc.
[0023] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A measurement circuit, characterized in that, Connected to the device under test (DUT), the measurement circuit is used to perform tests on electrical signals from the DUT. The measurement circuit includes a source measurement module and a preamplifier. The preamplifier includes a first operational amplifier, a first conversion module, and a second conversion module. The current gain of the preamplifier is controlled by controlling the ratio between the current flowing through the first conversion module and the current flowing through the second conversion module. The source measurement module is connected to the non-inverting input of the first operational amplifier. The first conversion module is connected between the non-inverting input and output of the first operational amplifier. The output of the first operational amplifier is connected to the device under test (DUT) through the second conversion module, and the inverting input of the first operational amplifier is connected to the DUT. The source measurement module outputs a first main signal, which is connected to the non-inverting input of the first operational amplifier and the first conversion module, respectively. The second main signal obtained from the first main signal is transmitted to the device under test through the inverting input of the first operational amplifier. The source measurement module samples the signal output by the first conversion module of the preamplifier, and the source measurement module samples and measures the current signal value in the first main signal. Based on the current signal value and the current gain of the preamplifier, the actual current value flowing through the device under test is obtained.
2. The measurement circuit according to claim 1, characterized in that, The first conversion module includes a first resistor, and the second conversion module includes a second resistor. The first resistor is connected between the non-inverting input terminal and the output terminal of the first operational amplifier, and the second resistor is connected between the output terminal of the first operational amplifier and the device under test. The resistance values of the first resistor and the second resistor are controlled respectively to control the ratio between the current flowing through the first conversion module and the current flowing through the second conversion module, thereby controlling the current gain of the preamplifier.
3. The measurement circuit according to claim 1, characterized in that, The first conversion module includes a second operational amplifier and a third resistor, and the second conversion module includes a fourth resistor. The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier, and the inverting input of the second operational amplifier is connected to the output of the second operational amplifier. The output of the second operational amplifier is connected to the non-inverting input of the first operational amplifier through the third resistor. The output of the first operational amplifier is connected to the device under test through the fourth resistor. The resistance values of the third resistor and the fourth resistor are controlled to control the ratio between the current flowing through the first conversion module and the current flowing through the second conversion module, thereby controlling the current gain of the preamplifier.
4. The measurement circuit according to claim 1, characterized in that, The first conversion module includes a fifth resistor, an amplification module, and a third operational amplifier. The second conversion module includes a sixth resistor. The first input terminal of the amplification module is connected to a signal equal to the first main signal voltage. The second input terminal of the amplification module is connected to the output terminal of the third operational amplifier. The output terminal of the amplification module is connected to the non-inverting input terminal of the first operational amplifier through the fifth resistor. The first input terminal of the third operational amplifier is connected to the output terminal of the first operational amplifier. The second input terminal of the third operational amplifier is connected to the output terminal of the third operational amplifier. The output terminal of the first operational amplifier is connected to the device under test through the sixth resistor. The resistance values of the fifth resistor and the sixth resistor are controlled to control the ratio between the current flowing through the first conversion module and the current flowing through the second conversion module, thereby controlling the current gain of the preamplifier.
5. The measurement circuit according to claim 4, characterized in that, The first input terminal of the amplification module is connected between the non-inverting input terminal of the first operational amplifier and the fifth resistor, so that the first input terminal of the amplification module is connected to a signal with a voltage equal to that of the first main signal; or, The first input terminal of the amplification module is connected between the inverting input terminal of the first operational amplifier and the device under test, so that the first input terminal of the amplification module receives a signal with a voltage equal to that of the first main signal.
6. The measuring circuit according to any one of claims 1 to 5, characterized in that, The protection signal output terminal of the source measurement module outputs a first protection signal, the voltage of which is equal to the voltage of the first main signal. The first protection signal is used to protect the preamplifier.
7. The measurement circuit according to claim 6, characterized in that, The measurement circuit further includes a floating power supply module, which generates a floating signal based on a reference signal, and then generates a first floating power supply signal and a second floating power supply signal using the floating signal as a reference. The first floating power supply signal and the second floating power supply signal are output to the preamplifier. The first floating power supply signal and the second floating power supply signal are symmetrical about the reference signal, which is either the first main signal or the first protection signal.
8. The measurement circuit according to claim 7, characterized in that, The floating power supply module includes a fourth operational amplifier, a first power supply circuit, and a second power supply circuit. The inverting input and output terminals of the fourth operational amplifier are connected, the positive input terminal of the first power supply circuit is connected to the first external power supply, the negative input terminal of the second power supply circuit is connected to the second external power supply, and the negative input terminal of the first power supply circuit and the positive input terminal of the second power supply circuit are connected to an analog reference ground signal. The reference signal is connected to the non-inverting input of the fourth operational amplifier. The fourth operational amplifier generates the floating signal based on the reference signal and outputs it to the negative output terminal of the first power supply circuit and the positive output terminal of the second power supply circuit. The first floating power signal generated by the first power supply circuit with reference to the floating signal is output from the positive output terminal to the preamplifier. The second floating power signal generated by the second power supply circuit with reference to the floating signal is output from the negative output terminal to the preamplifier.
9. The measurement circuit according to claim 1, characterized in that, The number of preamplifiers is two, and the output terminal of the first operational amplifier in one of the preamplifiers is connected to the first terminal of the device under test through the second conversion module, and the inverting input terminal is connected to the first terminal of the device under test. The output of the first operational amplifier in another preamplifier is connected to the second terminal of the device under test through the second conversion module, and the inverting input is connected to the second terminal of the device under test.
10. A testing device, characterized in that, The testing equipment includes multiple test channels, and each test channel includes a measurement circuit as described in any one of claims 1 to 9.