A picoampere-level low current test circuit suitable for ATE testing
By designing differential voltage testing circuits and equipotential protection circuits, the problem that ATE testing equipment is difficult to achieve pico-amplitude measurement accuracy is solved, the current measurement accuracy from nano-amplitude to pico-amplitude is improved, and the printed circuit board physics is reduced The impact of leakage.
Patent Information
- Application Number
- CN201911423784.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-12-31
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2039-12-31
AI Technical Summary
Existing ATE testing equipment is difficult to achieve the measurement accuracy of the pico-amplitude level and cannot effectively detect the chip's pico-amplitude level small current.
A pico-Axis-level small current testing circuit including a differential voltage testing circuit and an isopotential protection circuit is designed. Through the combination of a first operational amplifier, a series resistor and a chip to be tested, the leakage current of the chip to be tested is used. Convert to a voltage divider of series resistors to ensure that the test link is measured at isoelectric potential.
Improves the current measurement accuracy of ATE test equipment, from nano-amp level to pico-amp level, and reduces the impact of physical leakage of printed circuit boards, ensuring measurement accuracy and accuracy.
Smart Images
Figure CN110895290B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of test circuits, and in particular to a picoampere-level small current test circuit suitable for ATE testing. Background Art
[0002] As the integration of current chips is getting higher and higher, the market's requirements for chip power consumption are also getting higher and higher, so the allowable level of chip leakage has also increased from nanoamperes to picoamperes. However, it is difficult for the mainstream ATE test equipment in the current market to achieve picoampere-level measurement accuracy. The picoampere-level low-current test circuit is designed on the Load Board that connects the ATE test equipment and the chip to be tested, which can improve the current measurement accuracy of the current ATE test equipment from nanoamperes to picoamperes. Summary of the invention
[0003] In order to overcome the deficiencies in the prior art, the present invention provides a picoampere-level low-current test circuit suitable for ATE testing, which solves the problem that the ATE testing equipment in the prior art is difficult to achieve picoampere-level measurement accuracy.
[0004] In order to achieve the above-mentioned invention object, the technical solution adopted to solve the technical problem is as follows:
[0005] A picoampere-level low current test circuit suitable for ATE testing includes a differential voltage test circuit and an equipotential protection circuit, wherein:
[0006] The differential voltage test circuit includes a first operational amplifier, a series resistor and a chip to be tested, wherein the positive input terminal of the first operational amplifier is connected to the positive terminal of an external ATE differential voltage test device, the negative input terminal is connected to the right end of the series resistor, the output terminal of the first operational amplifier is respectively connected to the negative terminal of the external ATE differential voltage test device and the left end of the series resistor, and the right end of the series resistor is connected to the chip to be tested;
[0007] The equipotential protection circuit includes a second operational amplifier, a positive input terminal of the second operational amplifier is connected to the positive electrode of an external ATE differential voltage test device, and a negative input terminal is respectively connected to the output terminal of the second operational amplifier and the chip to be tested.
[0008] Furthermore, the resistance of the series resistor is selected to be in the order of hundreds of megohms.
[0009] Preferably, the resistance of the series resistor is 100 megaohms to 200 megaohms.
[0010] Furthermore, a voltage value of a right end of the series resistor is higher than a voltage value of a left end of the series resistor.
[0011] Furthermore, the load current on the series resistor is the same as the leakage current of the chip to be tested.
[0012] Furthermore, the leakage current of the chip to be tested is I=U / R, wherein U is the divided voltage of the series resistor, and R is the resistance value of the series resistor.
[0013] Furthermore, the input voltage of the positive input terminal of the first operational amplifier is the test voltage of the pin of the chip to be tested.
[0014] Furthermore, the input voltages of the positive input terminal and the negative input terminal of the first operational amplifier are the same.
[0015] Furthermore, the input voltage of the positive input terminal of the second operational amplifier is the test voltage of the pin of the chip to be tested.
[0016] Furthermore, the input voltages of the positive input terminal and the negative input terminal of the second operational amplifier are the same.
[0017] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:
[0018] The present invention discloses a picoampere-level low-current test circuit suitable for ATE testing. The picoampere-level low-current test circuit is designed on a Load Board that connects the ATE testing equipment with a chip to be tested, and the current measurement accuracy of the current ATE testing equipment can be improved from the nanoampere level to the picoampere level. Since the dielectric substrate of the printed circuit board cannot guarantee complete insulation in actual situations, it is necessary to consider the leakage of this part during the picoampere-level current test. The present invention adopts an equipotential voltage line to completely surround the measurement circuit of the chip pin to be tested, and the originally grounded part of the periphery of the test hole or the SMA test connector also needs to be connected to the equipotential line, which can ensure that the entire test link is at the equipotential level, thereby ensuring that it is affected as little as possible by the physical leakage of the PCB. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:
[0020] Figure 1 It is a schematic diagram of a picoampere current test circuit of the present invention;
[0021] Figure 2 It is the design diagram of the equipotential protection circuit Load Board of the present invention.
[0022]
Main symbols
[0023] 1- first operational amplifier;
[0024] 2- Series resistance;
[0025] 3- Chip to be tested;
[0026] 4- Second operational amplifier. DETAILED DESCRIPTION
[0027] The following will clearly and completely describe and discuss the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all the examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0028] like Figure 1 As shown, this embodiment discloses a picoampere-level low current test circuit suitable for ATE (Automatic Test Equipment) testing, including a differential voltage test circuit and an equipotential protection circuit, wherein:
[0029] The differential voltage test circuit includes a first operational amplifier 1, a series resistor 2 and a chip to be tested 3, wherein the positive input terminal of the first operational amplifier 1 is connected to the positive terminal of an external ATE differential voltage test device, and the negative input terminal is connected to the right end of the series resistor 2 (which can ensure the accuracy of the test voltage of the port of the chip to be tested 3, which is why the positive input voltages of the first operational amplifier 1 and the second operational amplifier 4 are set to the test voltage of the pin of the chip to be tested 3), the output terminal of the first operational amplifier 1 is respectively connected to the negative terminal of the external ATE differential voltage test device and the left end of the series resistor 2, and the right end of the series resistor 2 is connected to the chip to be tested 3;
[0030] The equipotential protection circuit includes a second operational amplifier 4, a positive input terminal of the second operational amplifier 4 is connected to the positive electrode of an external ATE differential voltage test device, and a negative input terminal is respectively connected to the output terminal of the second operational amplifier 4 and the chip 3 to be tested.
[0031] In this embodiment, according to the virtual short principle ("virtual short" means that under ideal conditions, the potentials of the two input terminals are equal, as if the two input terminals are short-circuited together, but in fact they are not short-circuited, which is called "virtual short"), it can be known that the positive measurement point of the ATE differential voltage measurement only needs to be placed at the input terminal, and the negative measurement point needs to be placed at the left end of the resistor.
[0032] Furthermore, since the current to be measured is in the picoampere level, the resistance of the series resistor 2 is selected to be in the order of hundreds of megohms. Preferably, the resistance of the series resistor 2 is 100 megohms to 200 megohms.
[0033] Furthermore, the actual divided voltage on the series resistor 2 is measured. According to the direction of the current, it can be known that the voltage value at the right end of the series resistor 2 is higher than the voltage value at the left end of the series resistor 2 .
[0034] Furthermore, since the series resistor 2 and the chip to be tested 3 in the circuit are in a series relationship, the load current on the series resistor 2 is the same as the leakage current of the chip to be tested 3 .
[0035] Furthermore, the actual leakage of the chip 3 to be tested is converted by directly measuring the leakage current into measuring the voltage divider of the series resistor 2. Specifically, the leakage current of the chip 3 to be tested is I=U / R, wherein U is the voltage divider of the series resistor 2, and R is the resistance value of the series resistor 2.
[0036] Furthermore, the positive input terminal of the second operational amplifier 4 of the equipotential protection circuit and the input terminal of the first operational amplifier 1 of the differential voltage measurement circuit use the same input voltage resource. Specifically, the input voltage of the positive input terminal of the first operational amplifier 1 is the test voltage of the pin of the chip 3 to be tested, and the input voltage of the positive input terminal of the second operational amplifier 4 is the test voltage of the pin of the chip 3 to be tested.
[0037] Further, according to the virtual short principle of the operational amplifier circuit, the input voltages of the positive input terminal and the negative input terminal of the first operational amplifier 1 are the same. Meanwhile, the input voltages of the positive input terminal and the negative input terminal of the second operational amplifier 4 are the same.
[0038] like Figure 2 As shown, the equipotential voltage line completely surrounds the measurement circuit of the 3-pin of the chip to be tested, which can ensure that the entire test link is at the same potential, thereby ensuring that it is affected as little as possible by the physical leakage of the PCB.
[0039] Further, such as Figure 2 As shown, the equipotential voltage line not only completely surrounds the measurement circuit of the 3-pin of the chip to be tested, but also the originally grounded part of the periphery of the test hole or the SMA test connector needs to be connected to the equipotential line.
[0040] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A picoampere-level low current test circuit suitable for ATE testing, characterized in that: It includes a differential voltage test circuit and an equipotential protection circuit, wherein: The differential voltage test circuit includes a first operational amplifier, a series resistor and a chip to be tested, wherein the positive input terminal of the first operational amplifier is connected to the positive terminal of an external ATE differential voltage test device, the negative input terminal is connected to the right end of the series resistor, the output terminal of the first operational amplifier is respectively connected to the negative terminal of the external ATE differential voltage test device and the left end of the series resistor, and the right end of the series resistor is connected to the chip to be tested; The equipotential protection circuit comprises a second operational amplifier, wherein the positive input terminal of the second operational amplifier is connected to the positive electrode of the external ATE differential voltage test equipment, and the negative input terminal is respectively connected to the output terminal of the second operational amplifier and the chip to be tested; The input voltage of the positive input terminal of the first operational amplifier is the test voltage of the pin of the chip to be tested; The input voltage of the positive input terminal of the second operational amplifier is the test voltage of the pin of the chip to be tested; Use equipotential voltage lines to completely surround the measurement circuit of the chip pin to be tested, and the originally grounded part around the test hole or SMA test connector also needs to be connected to the equipotential lines.
2. A picoampere-level low current test circuit suitable for ATE testing according to claim 1, characterized in that: The resistance value of the series resistor is selected to be in the order of hundreds of megohms.
3. A picoampere-level low current test circuit suitable for ATE testing according to claim 2, characterized in that: The resistance of the series resistor is 100 mega-200 mega ohms.
4. The picoampere-level low current test circuit suitable for ATE testing according to claim 1, characterized in that: The voltage value of the right end of the series resistor is higher than the voltage value of the left end of the series resistor.
5. The picoampere-level low current test circuit suitable for ATE testing according to claim 1, characterized in that: The load current on the series resistor is the same as the leakage current of the chip to be tested.
6. The picoampere-level low current test circuit suitable for ATE testing according to claim 5, characterized in that: The leakage current of the chip to be tested is I=U / R, wherein U is the divided voltage of the series resistor, and R is the resistance value of the series resistor.
7. The picoampere-level low current test circuit suitable for ATE testing according to claim 1, characterized in that: The input voltages of the positive input terminal and the negative input terminal of the first operational amplifier are the same.
8. The picoampere-level low current test circuit suitable for ATE testing according to claim 1, characterized in that: The input voltages of the positive input terminal and the negative input terminal of the second operational amplifier are the same.