Circular Iterative Calibration Method and Testing Equipment Using the Same

Abstract

A cyclic iterative calibration method and a test device using the same. The cyclic iterative calibration method includes: an inner loop step and an outer loop step. The inner loop step includes: adjusting the input power of a first known good unit according to a target power and an output power by a first gradient algorithm, and then adjusting the input power by a second gradient algorithm, wherein the step size of the first gradient algorithm is greater than that of the second gradient algorithm; and taking a first average value of the input power adjusted by the second gradient algorithm. The outer loop step includes: performing the inner loop step with a second known good unit to obtain a second average value of the second known good unit; and averaging the first average value and the second average value to obtain a final average value, and calibrating the test device according to the final average value. Its effects include being able to reduce the number of tests, improving the calibration efficiency, and being able to reduce the error caused by the working performance difference between multiple known good units or the random error of a single known good unit.

Description

Technical Field

[0001] The present invention relates to a related technology for chip unit testing, and particularly to a cyclic iterative calibration method and a testing device using the same. Background Art

[0002] During the production process of chip units, it is necessary to screen out chip units that meet the specifications through a testing device. However, the testing device usually generates errors due to minute environmental differences caused by factors such as an interface load board, a test card, hardware aging, or temperature. Therefore, it is necessary to calibrate the testing device using known good units (KGUs) that have been tested and meet the specifications, and then proceed with the testing and screening of the chip units.

[0003] For the power amplifier (PA) of a communication chip unit, when its power is at the intersection of the saturation region and the linear region, the linearity changes greatly, so it is not easy to calibrate or test. In addition, the working performances of multiple known good units are not exactly the same, and even a single known good unit has random errors. Moreover, if the input power is too large or the time is too long during testing or calibration, the temperature of the chip will rise, resulting in changes in the working performance. All these uncertainties will lead to low efficiency in calibration and testing and pose risks during production, thus there is a technical need. Summary of the Invention

[0004] One objective of the present invention is to provide a cyclic iterative calibration method and a testing device using the same, which can effectively improve the calibration efficiency.

[0005] An embodiment of the present invention provides a cyclic iterative calibration method and a test device using the same. The test device includes an interface carrier board, a test card, and a workstation. Known good units are provided on the interface carrier board. The workstation is used to execute a computer program to perform the cyclic iterative calibration method. The cyclic iterative calibration method includes an inner loop step and an outer loop step. The inner loop step includes: applying an input power to a first known good unit through the workstation and the test card, and measuring the output power of the first known good unit; the workstation adjusts the input power through a first gradient algorithm according to the target power and the output power, and then adjusts the input power through a second gradient algorithm, and the step size of the first gradient algorithm is greater than the step size of the second gradient algorithm; and the workstation takes a first average value of the input power adjusted by the second gradient algorithm. The outer loop step includes: performing the inner loop step with a second known good unit to obtain a second average value of the second known good unit; and the workstation takes an average of the first average value and the second average value to obtain a final average value, and performs calibration according to the final average value.

[0006] In an embodiment provided by the present invention, the inner loop step further includes: when no input power is applied, maintaining the working voltages of the first known good unit and the second known good unit through the test card, and turning off the amplifier modules in the first known good unit and the second known good unit.

[0007] In an embodiment provided by the present invention, the first gradient algorithm is an accelerated gradient algorithm, and the second gradient algorithm is a fixed gradient algorithm.

[0008] In an embodiment provided by the present invention, in the inner loop step, the number of times the workstation adjusts the input power through the first gradient algorithm according to the target power is not more than 3 times.

[0009] In an embodiment provided by the present invention, in the inner loop step, the workstation takes the first average value and the second average value of the input power after adjusting a predetermined number of times through the second gradient algorithm.

[0010] The embodiment of the present invention uses the first gradient algorithm to adjust the input power applied to the known good unit, and then adjusts the input power through the second gradient algorithm. Since the step size of the first gradient algorithm is greater than the step size of the second gradient algorithm, it can quickly approach the target input power and reduce the number of tests, improving the test efficiency. In addition, the embodiment of the present invention uses the method of taking the average value of the input power, which can reduce the error caused by the difference in working performance between multiple known good units or the random error of a single known good unit.

[0011] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically given, and in conjunction with the accompanying drawings, the details are described as follows. Description of the Drawings

[0012] Figure 1 It is a schematic diagram of the test equipment provided by the embodiment of the present invention.

[0013] Figure 2 It is a schematic flowchart of the cyclic iterative calibration method provided by the embodiment of the present invention.

[0014] Figure 3 It is a schematic diagram of the measured power consumption current value in the cyclic iterative calibration method provided by the embodiment of the present invention.

[0015] Figure 4 It is a schematic diagram of the output power versus the input power in the cyclic iterative calibration method provided by the embodiment of the present invention.

[0016] Figure 5 It is a schematic waveform diagram of the power consumption current in the cyclic iterative calibration method provided by the embodiment of the present invention. Detailed Embodiment

[0017] Figure 1 It is a schematic diagram of the test equipment provided by the embodiment of the present invention. In this embodiment, the test equipment 10, which can also be called a tester, includes an interface carrier board 101, a test head 102 (tester header), and a workstation 103. The test head 102 of the test equipment 10 can have various test cards, such as a device power supply test card 1021 (device power supply card), an RF test card 1022 (RF card), and a digital control test card 1023 (digital card), etc., but not limited thereto. Each test card is used for different test tasks. The test head 102 is electrically connected to the device under test (DUT) through the interface carrier board 101. For example, the wiring of the interface carrier board 101 electrically connects the probes of the test card and the pins of the device under test to transmit the resources of the test equipment 10, such as current, voltage, frequency, etc., to the device under test. When calibrating the test equipment 10, a known good unit (KGU) is used as the device under test. The known good unit KGU is, for example, a chip unit that has been tested in the laboratory and passed the specifications. Figure 1Take 4 known good units (KGUs) as an example, but not limited to this. The workstation 103 is, for example, a computer using a Windows or Linux system, having a memory, a processor, a display card, a screen, a human-machine interface, etc. The processor executes the computer program stored in the memory to perform the cyclic iterative calibration method, but not limited to this. Additionally, it should be supplemented that the number of original known good units (KGUs) is usually very small and cannot support the large-scale mass production requirements of the automatic test equipment (ATE) (usually the number of known good units (KGUs) provided by customers < 10 pcs). As the mass production starts to increase in volume, the number of these original known good units (KGUs) cannot support the calibration requirements of multiple test machines (testers). Moreover, it is also necessary to consider the loss of known good units (KGUs) during the normal mass production process. Therefore, it is very necessary to expand / collect the original small number of known good units (KGUs) into a certain number of known good units (KGUs) applicable to large-scale mass production while ensuring that the characteristics / data of the original known good units (KGUs) do not deviate. Therefore, a high-consistency KGU expansion / collection method is required, including the following steps: Step 1. Before the formal release of mass production, it is necessary to determine a certain position (site) on a certain carrier board (LB) as a reference (the corresponding position of this carrier board should have been confirmed to be problem-free in the laboratory and agreed upon by the customer), and all subsequent steps will use this position; Step 2. Test the original known good units (KGUs) using the cyclic iterative calibration method defined in the present invention; Step 3. Obtain the compensation value through the cyclic iterative calibration method defined in the present invention and use it in the program; Step 4. Pre-test 500 - 1000 pcs of mass production chip units in advance to obtain the overall characteristics of the current lot; Step 5. Use a script or other tools to tighten the limit of the current program according to the overall characteristics of the lot obtained in Step 4; and Step 6. Test the entire lot again and obtain known good units (KGUs) with higher consistency. In Step 5 (tightening the limit range), it is reasonably set according to the number of key test items to be compared. For example, after obtaining the lot characteristics in Step 4 (the maximum / minimum value (Max / Min) of each test item among 500 - 1000 pcs), the new limit range is tightened by 50%. If there are a total of 20 key test items to be compared, it may lead to a significant reduction in the number of known good units (KGUs) finally produced (since the average characteristics of the current lot have been mastered before, it is not an exponential relationship of decrease, but still may decrease significantly). In Step 6 (the final KGU output quantity), the result will be affected by the new limit setting in Step 5 (how many test items need to tighten the limit and how tightly the limit needs to be tightened). Through appropriate adjustment settings, it is recommended that the final output quantity of KGUs be kept below 10%.If the final output of the KGU is too high, it is necessary to increase the number of KGU in the formal mass production correction process to eliminate the error caused by the insufficient consistency of the KGU. Of course, the above combination is not fixed, and some experiments need to be done at the initial stage of mass production to balance the relationship between the yield of KGU output and the consistency of KGU.

[0018] Figure 2 It is a schematic flow chart of the cyclic iterative calibration method provided by the embodiment of the present invention. Figure 3 It is a schematic diagram of the measured power consumption current in the cyclic iterative calibration method provided by the embodiment of the present invention. Please refer to Figure 2 and Figure 3 . In this embodiment, as Figure 2 shown, the cyclic iterative calibration method performed by the test device 10 includes an inner loop step S10 and an outer loop step S20. Figure 3 shows the calibration records CL1, CL2, and CL3 of the three inner loop steps S10. The horizontal axis represents the number of measurements for each known good unit KGU; the vertical axis represents the difference between the measured power consumption current of the known good unit KGU and the target power consumption current, hereinafter referred to as ICC delta, in milliamperes (mA). In this embodiment, the target power consumption current of the known good unit KGU is used as a reference for the target power to calibrate the input power of the test device 10 to the known good unit KGU. As Figure 3 can be seen, as the number of input power adjustment times increases, the ICC delta gradually shrinks. However, the present invention is not limited thereto, and it may also be to calibrate the test device 10 by using the voltage of the known good unit KGU or referring to the voltage, current, or a combination thereof at different circuit nodes as a reference for the target power.

[0019] Figure 4 It is a schematic diagram of the output power versus the input power in the cyclic iterative calibration method provided by the embodiment of the present invention. Please refer to Figure 3 , Figure 4 , in Figure 3 shown in the calibration record CL3, it can be seen that after the 4th measurement, the ICC delta oscillates around plus or minus 20 mA. This is because when a relatively high power is input to the known good unit KGU, the known good unit KGU operates in a non-linear region (as Figure 4 shown, near point P2). Compared with operating in a linear region (as Figure 4 shown, near point P1), the power consumption current of the known good unit KGU operating in the non-linear region is sensitive and unstable, and even a slight change in the input power will have a great impact on the power consumption current of the known good unit KGU.

[0020] Please continue to refer to Figure 2In this embodiment, the inner loop step S10 includes steps S101 to S107. Next, steps S101 to S107 will be described.

[0021] Increment the measurement count value by 1 (step S101).

[0022] Apply input power to the known good unit KGU through the workstation 103 and the test head 102, and measure the output power of the known good unit KGU (step S103).

[0023] When the number of times of adjusting the input power (for example, the value obtained by subtracting 1 from the measurement count value or the number of times of adjusting the input power recorded separately) is no more than 3 times, the workstation 103 adjusts the input power according to the target power and the output power through the first gradient algorithm; when the number of times of adjusting the input power is greater than 3 times, the workstation 103 adjusts the input power according to the target power and the output power through the second gradient algorithm, where the step size of the first gradient algorithm is greater than the step size of the second gradient algorithm (step S105). Specifically, as Figure 3 shown, the ICC delta is relatively large during the first to fourth measurements. That is, during the previous adjustments of the input power, since the fluctuation of the output power accounts for a relatively small part of the ICC delta, it can be expected that the direction of adjusting the input power remains unchanged in the previous several times, that is, the input power needs to be increased or decreased in the previous several times. Therefore, first adjust the input power with the first gradient algorithm with a larger step size. The step size refers to parameters such as step size or learning rate that determine the update amount of the current input power and the next input power. Then, as Figure 3As shown, during measurements after the 5th time, the ICC delta is small, and the fluctuations in the output power start to account for the main part of the ICC delta. Therefore, the input power is adjusted using the second gradient algorithm with a smaller step size. Among them, the first gradient algorithm and the second gradient algorithm are, for example, accelerated gradient algorithms, such as algorithms like Nesterov Accelerated Gradient, and the step size (learning rate) used by the first gradient algorithm is greater than that of the second gradient algorithm; or, the first gradient algorithm and the second gradient algorithm are, for example, fixed gradient algorithms, where the second gradient algorithm adjusts the input power with a step size (learning rate) of 0.15 dBm, and the step size used by the first gradient algorithm is greater than 0.15 dBm, for example, twice that of the second gradient algorithm; or, the first gradient algorithm and the second gradient algorithm can also be a combination of the above algorithms. For example, the first gradient algorithm is an accelerated gradient algorithm, and the second gradient algorithm is a fixed gradient algorithm, but it is not limited to this. In short, for fast convergence, a search with a larger step size is implemented in the first few loop iterations, and the next search is set based on the slope of this time and the result of the previous time. It can be expected that the known good unit KGU should still operate within the linear region and will not be greatly affected by temperature from the beginning. And a search with a smaller step size is implemented after the search with a larger step size (usually 3 steps). There are two reasons for this: a. Searching multiple times may cause a significant increase in the heat / temperature of the known good unit KGU, which will lead to a decrease in the performance of the known good unit KGU, and the search may also exceed expectations and will no longer be suitable; b. The approaching target is usually at the boundary between the linear and saturation regions, resulting in too low a qualification rate, and the adjustment method is not a suitable part for the edge units. If the search is incorrect, oscillations may occur and it may never converge even if the calibration time is increased. Therefore, they are combined to perform faster, more stable / repeatable calibration.

[0024] When the measurement count value is less than 20 times, return to step S101; when the measurement count value is equal to 20 times, the workstation 103 resets the measurement count value to zero, and filters and takes the average value of the input power after being adjusted a predetermined number of times by the second gradient algorithm (step S107). For example, 20 mA is used as the screening condition, and the above-mentioned predetermined number of times is taken as 10 adjustments for example, then Figure 3In the calibration records CL1 and CL2 shown, the ICC deltas after 10 adjustments are all within 20 mA. Therefore, all the input powers after 10 adjustments will be used to calculate the average value. In the calibration record CL3, the ICC delta measured at the 17th time is greater than 20 mA. Therefore, the input power at the 17th time is excluded from all the input powers after 10 adjustments, and the remaining input powers are used to calculate the average value. In other embodiments, it is also possible to return to step S101 at different measurement count values, for example, preferably more than 10 times to reduce errors, but not limited to this.

[0025] Therefore, although it is known that the good unit KGU may be in different operating ranges during calibration and have output power curves in different forms as shown in the calibration records CL1 to CL3 Figure 3 in this embodiment, the inner loop step S10 provided enables the output power curves in different forms to be applicable by taking the average value, reducing the need for manual operation and having good versatility.

[0026] Please continue to refer to Figure 2 In this embodiment, the outer loop step S20 includes the following steps: performing the above inner loop step S10 on each known good unit KGU to obtain the average value of the input power of each known good unit KGU (step S201); and screening and taking the final average value of the average values of the input powers of each known good unit KGU, and performing calibration according to the final average value (step S203). Specifically, after obtaining multiple average values of the input powers of all known good units KGU, the extreme values or values that do not meet the conditions in the multiple average values are screened out and not used, and the remaining average values are taken as the final average value.

[0027] For example, when using 10 known good units KGU to perform the cyclic iterative calibration method, the outer loop step S20 includes: performing the above inner loop step S10 on the first known good unit KGU to obtain the first average value of the input power of the first known good unit KGU; then performing the above inner loop step S10 on the second known good unit KGU to obtain the second average value of the input power of the second known good unit KGU; and so on until obtaining the tenth average value of the input power of the tenth known good unit KGU. Then, the extreme values or average values that do not meet the conditions with large differences are screened out and not used from the first average value to the tenth average value, and the remaining average values are taken as the final average value. Finally, the workstation 103 performs calibration according to the final average value. In other embodiments, it is also possible to use more than 10 known good units KGU, such as 20 or more.

[0028] Figure 5It is a waveform diagram of the power consumption current in the loop iteration calibration method provided by the embodiment of the present invention. During the process of performing the inner loop step S10 on the known good unit (KGU), the step S103 will be performed multiple times, that is, the known good unit (KGU) is input with power multiple times (such as waveform 4) and the output power (power consumption current, such as waveforms 1 to 3) is measured. During the time interval from the end of inputting power to the known good unit (KGU) and measuring the output power to the next time of inputting power, for example, between time T2 and T3 or between time T4 and T5 shown in waveform 3, the known good unit (KGU) still has a normal working power consumption current, and such a power consumption current will also cause the known good unit (KGU) to heat up. Therefore, in this embodiment, as shown in waveform 1, the working voltage VCC of the known good unit (KGU) is maintained by the device power supply test card 1021, and a signal is sent to the control module of the known good unit (KGU) through the digital control test card 1023 to turn off the amplifier module in the known good unit (KGU) from the end of measuring the output power to the next time of inputting power, thereby avoiding test errors caused by adjusting the working voltage and reducing the change of working characteristics due to the heating of the amplifier module. The above method of turning off the amplifier module in the known good unit (KGU) is not limited to this, and it can also be to turn off the amplifier module in the known good unit (KGU) externally through the interface carrier board 101 or the test head 102, etc. In addition, it is not necessary to turn off the amplifier module in the known good unit (KGU) every time the input power ends, and it can also be selectively turned off only after a specific number of times of inputting power ends. For example Figure 5 shown in waveform 1, it is turned off only once every two times of inputting power. In other embodiments, it can also be turned off when adjusting the input power using the first gradient algorithm and not turned off when adjusting the input power using the second gradient algorithm. In other embodiments, when no power is input to this known good unit (KGU), it can also be as shown in Figure 5 waveform 2, the power supply VCC provided to the known good unit (KGU) is turned off or reduced by the device power supply test card 1021 to reduce the temperature rise.

[0029] It should be noted that in other embodiments, different numbers of times of adjusting the input power can also be used as the basis for the switching algorithm. For example, the number of times of adjusting the input power using the first gradient algorithm can also be less than 3 times or more than 3 times. And the step size of the first gradient algorithm or the second gradient algorithm can also be adjusted. For example, reduce the number of times of adjusting the input power using the first gradient algorithm and increase the step size, or increase the number of times of adjusting the input power using the first gradient algorithm and reduce the step size. In addition, the number of times can also not be used as the basis for the switching algorithm. For example, at step S105, when the measured output power approaches the target value within a range (for example, refer to Figure 3, when the ICC delta is less than 40 mA), the next adjustment switches to using the second gradient algorithm to adjust the input power. It should be noted that the basis for switching the gradient algorithm, the step size used in the gradient algorithm, and the predetermined number of times for taking the average can all be adjusted through the workstation 103 according to the measurement results or actual requirements, such as by modifying the parameters used in the computer program or rewriting the computer program.

[0030] In summary, the embodiment of the present invention uses the first gradient algorithm to adjust the input power applied to the known good unit, and then adjusts the input power through the second gradient algorithm. Since the step size of the first gradient algorithm is greater than that of the second gradient algorithm, it can quickly approach the target input power and reduce the number of tests, improving the test efficiency. In addition, the embodiment of the present invention adopts the method of taking the average of multiple input powers adjusted by the second gradient algorithm with a smaller step size for a single known good unit, which can avoid the fluctuations caused by the known good unit working in the non-linear interval. Moreover, the embodiment of the present invention adopts the method of taking the final average of the average input powers of each known good unit, which can reduce the errors caused by the differences in working performance between multiple known good units or the random errors of a single known good unit.

[0031] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the equivalent embodiments by using the methods and technical contents disclosed above within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A test device using a cyclic iteration calibration method, characterized in that, The test device includes an interface carrier board, a test card, and a workstation. Known good units are provided on the interface carrier board. The workstation is used to execute a computer program to perform the cyclic iterative calibration method. The cyclic iterative calibration method includes: An inner loop step, including: Applying an input power to a first known good unit through the workstation and the test card, and measuring the output power of the first known good unit; The workstation adjusts the input power according to the target power and the output power, first by a first gradient algorithm and then by a second gradient algorithm. The step size of the first gradient algorithm is greater than that of the second gradient algorithm; and The workstation takes a first average value of the input power adjusted by the second gradient algorithm; and An outer loop step, including: Performing the inner loop step with a second known good unit to obtain a second average value of the second known good unit; and The workstation averages the first average value and the second average value to obtain a final average value, and performs calibration according to the final average value.

2. The test device according to claim 1, wherein, The inner loop step further includes: when the input power is not applied, maintaining the operating voltages of the first known good unit and the second known good unit through the test card, and turning off the amplifier modules in the first known good unit and the second known good unit.

3. The test device according to claim 1, characterized in that, The first gradient algorithm is an accelerated gradient algorithm, and the second gradient algorithm is a fixed gradient algorithm.

4. The test device according to claim 1, characterized in that In the inner loop step, the number of times the workstation adjusts the input power by the first gradient algorithm according to the target power is not more than 3 times.

5. The test device according to claim 1, characterized in that In the inner loop step, the workstation takes the first average value and the second average value of the input power adjusted by the second gradient algorithm after a predetermined number of times.

6. A cyclic iterative calibration method, applicable to a test device, characterized in that, The test device includes an interface carrier board, a test card, and a workstation. Known good units are provided on the interface carrier board. The workstation is used to execute a computer program to perform the cyclic iterative calibration method. The cyclic iterative calibration method includes: An inner loop step, including: Applying an input power to a first known good unit through the workstation and the test card, and measuring the output power of the first known good unit; The workstation adjusts the input power according to the target power and the output power, first by a first gradient algorithm and then by a second gradient algorithm. The step size of the first gradient algorithm is greater than that of the second gradient algorithm; and The workstation takes a first average value of the input power adjusted by the second gradient algorithm; and An outer loop step, including: Performing the inner loop step with a second known good unit to obtain a second average value of the second known good unit; and The workstation averages the first average value and the second average value to obtain a final average value, and performs calibration according to the final average value.

7. The cyclic iterative calibration method according to claim 6, wherein The inner loop step further includes: when the input power is not applied, maintaining the operating voltages of the first known good unit and the second known good unit through the test card, and turning off the amplifier modules in the first known good unit and the second known good unit.

8. The cyclic iterative calibration method according to claim 6, wherein, The first gradient algorithm is an accelerated gradient algorithm, and the second gradient algorithm is a fixed gradient algorithm.

9. The cyclic iterative calibration method according to claim 6, wherein, In the inner loop step, the number of times the workstation adjusts the input power through the first gradient algorithm according to the target power is not more than 3 times.

10. The cyclic iterative calibration method according to claim 6, wherein In the inner loop step, the workstation takes the first average value and the second average value of the input power after the second gradient algorithm has adjusted it a predetermined number of times.

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