Calibration circuit of precision measurement unit

Abstract

The utility model provides a precision measurement unit calibration circuit, which is applied to the technical field of semiconductor chip testing, and comprises a power supply circuit, a controller, an analog multiplexer, an analog-to-digital conversion circuit and a sampling resistor, the power supply circuit provides various working power supplies after stabilizing the voltage of an input power supply; the analog multiplexer and the sampling resistor are connected with a driving circuit and a sensing circuit of the precision measurement unit; the analog-to-digital conversion circuit performs digital conversion on measurement output of the precision measurement unit and transmits a digital result to the controller; the controller carries out detection and calibration configuration on the precision measurement unit. The calibration circuit is arranged on the circuit board of the precision measurement unit, so that detection and calibration can be carried out anytime and anywhere, the precision measurement unit is timely guaranteed to be free of faults, and the precision measurement unit is guaranteed to have very high precision.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor chip testing, and in particular to a precision measurement unit calibration circuit for semiconductor chip signal testing. Background Art

[0002] At present, the communication industry and consumer electronics industry are developing rapidly, and the market has put forward higher requirements for product-related performance, which has greatly promoted the development of miniaturization and integration of semiconductor devices. Correspondingly, there are also higher requirements for the test technology of semiconductor devices, such as the increasing complexity of test signals, the increasing accuracy requirements of test signals, the increasing number of load functions, and the increasing current. The overall trend puts forward higher requirements for the PMU (Precision Measurement Unit) used for test signals, causing the functions of PMU to become more and more complex, making it difficult to ensure the accuracy of PMU, and thus resulting in the final test accuracy and test efficiency being significantly restricted by the accuracy of PMU.

[0003] In addition, existing PMU calibration schemes are limited by the calibration circuit, and the calibration accuracy is usually not high. The calibration operation is also relatively slow. Some calibrations also require external calibration equipment, or even the PMU needs to be removed and special equipment needs to be used to complete the calibration, which seriously affects the semiconductor chip signal test.

[0004] Based on this, a new PMU calibration technology solution is needed. Utility Model Content

[0005] In view of this, the embodiments of the present specification provide a precision measurement unit calibration circuit for semiconductor chip signal testing. By designing a high-precision calibration circuit in the PMU, not only can the PMU be calibrated at any time, but the PMU accuracy can also be improved, thereby ensuring that the PMU has high test accuracy and test efficiency in signal testing scenarios.

[0006] The embodiments of this specification provide the following technical solutions:

[0007] The embodiment of this specification provides a precision measurement unit calibration circuit, including: a power supply circuit, a controller, an analog multiplexer, an analog-to-digital conversion circuit, and a sampling resistor;

[0008] The power supply circuit is used to provide corresponding working power to the controller, the analog multiplexer, the analog-to-digital conversion circuit and the precision measurement unit to be calibrated respectively after stabilizing the input power supply;

[0009] The analog multiplexer includes a first group of multiplex switches and a second group of multiplex switches; wherein the common end of the first group of multiplex switches is electrically connected to the driving circuit of the precision measurement unit, the common end of the second group of multiplex switches is electrically connected to the sensing circuit of the precision measurement unit, the address end and the enable end of the first group of multiplex switches, and the address end and the enable end of the second group of multiplex switches are electrically connected to the controller respectively, and the multiplex channel end of the first group of multiplex switches is correspondingly connected to the multiplex channel end of the second group of multiplex switches and is electrically connected to the sampling resistor;

[0010] The analog-to-digital conversion circuit is electrically connected to the measurement output terminal of the precision measurement unit and the first communication interface of the controller respectively, and is used to digitally convert the measurement output of the precision measurement unit and transmit the converted digital signal to the controller;

[0011] The second communication interface of the controller is electrically connected to the communication interface of the precision measurement unit, and is used to configure the precision measurement unit to output a corresponding drive signal to the sampling resistor through the drive circuit, and to configure the precision measurement unit to obtain a corresponding sampling signal formed by the drive signal on the sampling resistor through the sensing circuit.

[0012] Preferably, the power supply circuit comprises: a first power supply circuit, a second power supply circuit and a third power supply circuit;

[0013] The first power supply circuit is used to stabilize the input power supply and then provide the analog power supply positive voltage required for the operation of the analog circuit to the precision measurement unit, the second power supply circuit, the third power supply circuit, and the analog multiplexer respectively;

[0014] The second power supply circuit is used to provide the analog power supply negative voltage required for the operation of the analog circuit to the precision measurement unit and the analog multiplexer respectively after stabilizing the working power supply provided by the first power supply circuit;

[0015] The third power supply circuit is used to provide the digital power supply voltage required for the operation of the digital circuit to the precision measurement unit and the controller respectively after stabilizing the working power provided by the first power supply circuit.

[0016] Preferably, the first power supply circuit comprises a Boost circuit, wherein the Boost circuit is used to output a first positive voltage as a positive analog power supply voltage after boosting and stabilizing the input power supply;

[0017] The second power supply circuit includes a Buck circuit, wherein the Buck circuit is used to output a first negative voltage as an analog power supply negative voltage after stabilizing the first positive voltage;

[0018] The third power supply circuit includes a linear voltage stabilization circuit, wherein the linear voltage stabilization circuit is used to output a second positive voltage as a digital power supply voltage after voltage reduction and voltage stabilization according to the first positive voltage.

[0019] Preferably, the calibration range of the precision measurement unit includes -10V to 10V or -10V to 12.5V, the voltage value of the input power supply is 12V, the positive voltage of the analog power supply is 15V, the negative voltage of the analog power supply is -15V, and the digital power supply voltage is 3.3V.

[0020] Preferably, when the precision measurement unit includes a plurality of measurement channels, the precision measurement units share the analog-to-digital conversion circuit.

[0021] Preferably, the first group of multiplexing switches and the second group of multiplexing switches are both SP4T switches, and the sampling circuit includes a first resistor, a second resistor and a third resistor;

[0022] wherein the first channel port of the first group of multiplexing switches and the first channel port of the second group of multiplexing switches are connected to a signal ground;

[0023] The second channel port of the first group of multiplexing switches and the second channel port of the second group of multiplexing switches are connected to one end of the first resistor, and the other end of the first resistor is connected to the signal ground;

[0024] The third channel port of the first group of multiplexing switches and the third channel port of the second group of multiplexing switches are connected to one end of the second resistor, and the other end of the second resistor is connected to the signal ground;

[0025] The fourth channel port of the first group of multiplexing switches and the fourth channel port of the second group of multiplexing switches are connected to one end of the third resistor, and the other end of the third resistor is connected to the signal ground.

[0026] Preferably, the controller is a single-chip microcomputer, and the communication interface of the precision measurement unit includes a SIP interface; wherein the controller is electrically connected to the communication interface of the precision measurement unit includes: the GPIO of the single-chip microcomputer is electrically connected to the corresponding SIP interface of the precision measurement unit;

[0027] And / or, the controller is further configured to load a new calibration value into a register of the precision measurement unit via the communication interface when it is determined that the error of the sampling signal deviating from the calibration signal exceeds an error threshold.

[0028] Preferably, in any one of the precision measurement unit calibration circuits described in the present application, a driving circuit of the precision measurement unit is also electrically connected to an external measurement device.

[0029] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0030] By designing the calibration circuit directly onto the PMU circuit board, repeated disassembly and assembly of the PMU is avoided. In a test environment, the PMU can be quickly tested and calibrated through direct programming, ensuring that the PMU has very good accuracy and precision in semiconductor product testing. In addition, the PMU can be calibrated and tested at any time, for example, when the device is just powered on or after the device has been used for a period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a structural schematic diagram of a PMU calibration circuit in this application;

[0033] Figure 2 It is a schematic diagram of the structure of the power supply circuit in this application;

[0034] Figure 3 It is a connection diagram of the driving circuit and the sensing circuit in this application;

[0035] Figure 4 is a connection diagram of the analog-to-digital conversion circuit in this application;

[0036] Figure 5 It is the overall circuit diagram in this application;

[0037] Figure 6 It is a connection diagram of the PMU test channel connected to the analog-to-digital conversion circuit in this application. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0039] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0040] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0041] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0042] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0043] Semiconductor products (such as wafers, dies on wafers, integrated circuits, etc.) need to undergo large-scale semiconductor product testing after they are manufactured and delivered for use. In semiconductor testing, the die on the wafer or the final packaged component is used as the device under test (DUT), which is usually connected to automatic test equipment (ATE) for testing. Specifically, ATE applies power, analog signals and other test signals to it, and ATE detects its output to determine whether the DUT has defects and the performance level.

[0044] A precision measurement unit (PMU) is a test circuit in ATE, usually used for precise DC parameter measurement. The PMU first applies (i.e. drives) a test signal (such as current, voltage) to the DUT, and then measures the output signal (such as current, voltage) output by the DUT, thereby judging the defects, performance, etc. of the DUT through the output signal.

[0045] Therefore, the accuracy of the PMU itself has a very important impact on semiconductor testing, so PMU needs to be calibrated for daily maintenance in semiconductor testing applications. With the application of semiconductor devices in various industries, the market demand for semiconductor devices is increasingly strong, and the semiconductor production capacity has entered a stage of rapid growth. At this time, the existing PMU calibration scheme can no longer meet the testing needs under the new production capacity. For example, due to the low calibration accuracy, the PMU's own accuracy is limited, and the calibration operation is relatively slow. Some calibrations also require external calibration equipment, and even the PMU needs to be removed and special equipment is used to complete the calibration, which seriously affects the semiconductor testing work and makes semiconductor testing a bottleneck of semiconductor production capacity.

[0046] In view of this, through in-depth research and improvement exploration of PMU and its calibration scheme, it is found that:

[0047] On the one hand, PMU is a specific device for measuring semiconductor DC parameters. If the circuit for PMU calibration can be designed on the PMU circuit board, calibration can be carried out at any time. For example, when the device is just powered on or after the device has been used for a period of time, the calibration can be completed through this circuit, avoiding the need to connect other calibration equipment or even disassemble the PMU to complete the calibration work. In this way, a lot of time will be shortened in the PMU calibration work, and timely calibration can be carried out even in different test environments, ensuring the accuracy and precision of the PMU. When the calibrated PMU is used to complete the test, the quality of the semiconductor products will be guaranteed.

[0048] Secondly, the existing solution cannot determine at any time whether the PMU needs to be calibrated, let alone whether the PMU has an internal fault. If a detection circuit can be set on the periphery of the PMU to detect whether the PMU needs to be calibrated, or even whether there is a fault inside the PMU, that is, a pre-calibration detection circuit is set outside the PMU, it can quickly determine whether the PMU needs to be calibrated, and even quickly determine whether there is a fault inside the PMU, so that the PMU can be calibrated in time, and even a faulty PMU can be detected, avoiding the use of a PMU with performance problems to test semiconductor products;

[0049] Third, since the internal space of the PMU is limited and the calibration accuracy is required to be high, the improved circuits in the above two aspects should not take up too much circuit board space, but should also be able to ensure that the PMU completes the calibration accuracy requirements. Therefore, the circuit form also needs to be as short and high-precision as possible.

[0050] Based on this, the embodiment of this specification proposes a PMU calibration circuit solution: Figure 1The precision measurement unit calibration circuit 10 shown may include: a power supply circuit 110 , a controller 120 , an analog multiplexer and sampling resistor 130 , and an analog-to-digital conversion circuit 140 .

[0051] During implementation, the power supply circuit 110 forms a high-precision power supply voltage after stabilizing the input power supply. These high-precision power supply voltages respectively provide the working power required by circuits such as the controller 120, the analog multiplexer 130, the analog-to-digital conversion circuit 140 and the precision measurement unit 20 to be calibrated.

[0052] Specifically, the power supply circuit 110 can form a corresponding working voltage after stabilizing the working voltage required by each circuit, and the voltage stabilizing circuit used for voltage stabilization can select an existing mature voltage stabilizing circuit according to the voltage stabilization needs, such as a linear voltage stabilizing circuit, a switching voltage stabilizing circuit, etc., so that after voltage stabilization, it can provide high-precision working power to each circuit in the calibration circuit.

[0053] For example, the PMU usually includes analog circuits operating at a higher voltage and digital circuits operating at a lower voltage. For example, the analog circuit's operating power supply is a dual power supply (such as ±15V) and the digital circuit is a single power supply (such as 3.3V). In this case, the power supply circuit 110 can provide these power supplies through a voltage stabilizing circuit.

[0054] In the implementation, the analog multiplexer 130 includes a first group of multiplex switches and a second group of multiplex switches; wherein the common end of the first group of multiplex switches is electrically connected to the drive line (Force Lines) of the precision measurement unit 20, the common end of the second group of multiplex switches is electrically connected to the sense line (Sense Lines) of the precision measurement unit, the address end and the enable end of the first group of multiplex switches, and the address end and the enable end of the second group of multiplex switches are electrically connected to the GPIO of the controller respectively, and the multiplex channel end of the first group of multiplex switches is correspondingly connected to the multiplex channel end of the second group of multiplex switches and is connected to the sampling resistor (for example Figure 3 A connection diagram is shown).

[0055] The sampling resistor may be used as a device under test (DUT) used by the PMU in calibration, that is, the PMU applies a driving signal to the sampling resistor and senses and obtains a corresponding sampling signal from the sampling resistor.

[0056] In addition, the analog multiplexer (ie, multiplexing switch) can select a circuit form that provides a bidirectional path between input and output, and a circuit form with good signal integrity, small crosstalk and leakage current, which is more conducive to ensuring the accuracy of PMU calibration.

[0057] During implementation, the analog input end of the analog-to-digital conversion circuit is connected to the measurement output end of the precision measurement unit, and the digital interface of the mode conversion circuit is electrically connected to the first communication interface (such as the SPI interface) of the controller. At this time, the analog-to-digital conversion circuit can digitally convert the measurement output of the precision measurement unit, thereby transmitting the converted digital signal to the controller.

[0058] During implementation, the second communication interface (such as an SPI interface) of the controller is electrically connected to the communication interface of the precision measurement unit, and then the precision measurement unit can be configured to output a corresponding drive signal to the sampling resistor through the drive circuit, and the precision measurement unit can be configured to obtain a corresponding sampling signal formed by the drive signal on the sampling resistor through the sensing circuit.

[0059] Figure 2 A PMU calibration circuit is illustrated, the power supply circuit includes: a first power supply circuit, a second power supply circuit and a third power supply circuit, wherein the first power supply circuit is a voltage stabilizing circuit with the voltage regulator Power IC_1 as the core, the second power supply circuit is a voltage stabilizing circuit with the voltage regulator Power IC_2 as the core, and the third power supply circuit is a voltage stabilizing circuit with the voltage regulator PowerIC_3 as the core.

[0060] Specifically, Power IC_1 can be a boost circuit with a single-channel voltage regulation output or a multi-channel voltage regulation output. For example, a multi-channel output circuit can output multiple output voltages to the outside, and a single-channel voltage regulation circuit can output the same output voltage to the outside. The output voltage provides the analog power positive voltage required for the analog circuit to work, such as 15V, to the precision measurement unit (PMU), the second power circuit, the third power circuit, the analog multiplexer (Analog switch) and other circuits.

[0061] Power IC_2 can be a Buck circuit with a single-channel regulated output or a multi-channel regulated output, so that after a negative voltage regulated output is performed according to the working power provided by the first power supply circuit, the negative voltage can provide the analog power negative voltage required for the operation of the analog circuit to the precision measurement unit and the analog multiplexer, such as -15V.

[0062] Power IC_3 can be a linear voltage regulator circuit with single-channel voltage regulation output or multi-channel voltage regulation output, so that after voltage regulation based on the working power provided by the first power supply circuit, the digital power supply voltage required for the operation of the digital circuit, such as 3.3V, can be provided to the precision measurement unit and the controller respectively.

[0063] See also Figure 3Schematically, the first group of multiplexing switches and the second group of multiplexing switches are both SP4T switches, and the sampling circuit includes a first resistor R1, a second resistor R2 and a third resistor R3, and each sampling resistor is connected in series between the channel port of the first group of multiplexing switches and the signal ground.

[0064] Specifically, the first channel port (i.e., port S1) of the first group of multiplexing switches and the first channel port of the second group of multiplexing switches are connected to the signal ground; the second channel port (i.e., port S2) of the first group of multiplexing switches and the second channel port of the second group of multiplexing switches are connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to the signal ground; the third channel port (i.e., port S3) of the first group of multiplexing switches and the third channel port of the second group of multiplexing switches are connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the signal ground; the fourth channel port (i.e., port S4) of the first group of multiplexing switches and the fourth channel port of the second group of multiplexing switches are connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the signal ground.

[0065] refer to Figure 4 The analog-to-digital conversion circuit can be used to digitize the MEASOUT output of the PMU and send the digitized result to the MCU through the SPI interface. The MEASOUT pin of the PMU can be connected to the ADC after passing through an optocoupler and then through a resistor and capacitor (the resistor and capacitor form an RC low-pass filter to filter out high-frequency interference), and the ADC returns the test data to the MCU through the SPI protocol.

[0066] refer to Figure 5 The input power supply 12V passes through REF_IC (such as LT6654-5V) to power ADC1; the measout pin of PMU is connected to ADC_1 after being isolated by optocoupler (Relay) and then filtered by resistors and capacitors (resistors and capacitors form an RC low-pass filter to filter out high-frequency interference). ADC_1 returns the test data to MCU through the SPI protocol, and the MCU sends the test data to the host computer (such as a computer) through USB.

[0067] refer to Figure 6 , one channel can use one RELAY, so when the PMU has 4 channels, 4 RELAYs are used. In addition, when the MCU controls the GPIO to a high level, pin3 and pin4 of RELAY are turned on, pin4 is connected to the resistor, and the resistor is connected to the ADC for testing.

[0068] In some examples, the MCU can also send the test data to the PC via USB.

[0069] Based on the above calibration circuit, the present application also provides a precision measurement unit calibration method using the circuit for calibration, so as to perform detection, calibration test, etc. on the PMU based on any one of the above precision measurement unit calibration circuits.

[0070] The precision measurement unit calibration method provided in the present application may include:

[0071] Step S202, controlling the precision measurement unit to enter a preset target mode, and selecting a first measurement range and a first error corresponding to the target mode;

[0072] Step S204, controlling the precision measurement unit to sequentially generate a driving signal according to the target mode, and controlling the precision measurement unit to obtain a sampling signal corresponding to the calibration signal;

[0073] Step S206, determining an error value between the calibration signal and its corresponding sampling signal;

[0074] Step S208, determining whether the error value exceeds the first error, if so, determining that the PMU needs to be calibrated, and triggering the precision measurement unit to perform calibration, otherwise determining that the precision measurement unit does not need to be calibrated.

[0075] The following is a brief introduction of the working process of the calibration circuit in the form of an example and in combination with the attached drawings:

[0076] (1) The input interface provides 12V power supply;

[0077] (2) The input power uses the Boost method to output a 15V voltage to power the PMU through power IC_1;

[0078] (3) Power IC_2 uses Buck mode to output a -15V voltage through path ① to power the PMU that requires a negative power supply;

[0079] (4) Power IC_3 outputs a 3.3V voltage through path ② using LDO step-down to power the PMU and MCU;

[0080] (5) The controller MCU communicates with the PMU via the SPI protocol;

[0081] (6) The PMU enters FVMV (force voltage measure voltage) mode and selects an appropriate range to start testing the PMU function. For example, set the PMU test voltage range to -10 to +10 V, then select the first channel of the PMU to start testing. After the first channel is tested, test the second channel, and so on until the last channel is tested.

[0082] The following example uses the PMU test voltage range of -10 to +10V, with a step of 0.5V and an error range of 2% to carry out FVMU testing, and the test is carried out according to the following process:

[0083] (1) When Force voltage = -10V, check whether the measured voltage is equal to -10V±2%;

[0084] (2) When Force voltage = -9.5V, check whether the measured voltage is equal to -9.5V ± 2%;

[0085] (3) When Force voltage = -9V, check whether the measured voltage is equal to -9V ± 2%;

[0086] (4) When Force voltage = -8.5V, check whether the measured voltage is equal to -8.5V ± 2%;

[0087] (5) When Force voltage = -8V, check whether the measured voltage is equal to -8V ± 2%;

[0088] (6) When Force voltage = -7.5V, check whether the measured voltage is equal to -7.5V ± 2%;

[0089] (7) When Force voltage = -7V, check whether the measured voltage is equal to -7V ± 2%;

[0090] (8) When Force voltage = -6.5V, check whether the measured voltage is equal to -6.5V ± 2%;

[0091] (9) When Force voltage = -6V, check whether the measured voltage is equal to -6V ± 2%;

[0092] (10) When Force voltage = -5.5V, check whether the measured voltage is equal to -5.5V±2%;

[0093] (11) When Force voltage = -5V, check whether the measured voltage is equal to -5V ± 2%;

[0094] (12) When Force voltage = -4.5V, check whether the measured voltage is equal to -4.5V ± 2%;

[0095] (13) When Force voltage = -4V, check whether the measured voltage is equal to -4V±2%;

[0096] (14) When Force voltage = -3.5V, check whether the measured voltage is equal to -3.5V ± 2%;

[0097] (15) When Force voltage = -3V, check whether the measured voltage is equal to -3V ± 2%;

[0098] (16) When Force voltage = -2.5V, check whether the measured voltage is equal to -2.5V±2%;

[0099] (17) When Force voltage = -2V, check whether the measured voltage is equal to -2V ± 2%;

[0100] (18) When Force voltage = -1.5V, check whether the measured voltage is equal to -1.5V±2%;

[0101] (19) When Force voltage = -1V, check whether the measured voltage is equal to -1V ± 2%;

[0102] (20) When Force voltage = -0.5V, check whether the measured voltage is equal to -0.5V ± 2%;

[0103] (21) When Force voltage = 0V, check whether the measured voltage is equal to 0V ± 2%;

[0104] (22) When Force voltage = 0.5V, check whether the measured voltage is equal to 0.5V ± 2%;

[0105] (23) When Force voltage = 1V, check whether the measured voltage is equal to 1V ± 2%;

[0106] (24) When Force voltage = 1.5V, check whether the measured voltage is equal to 1.5V ± 2%;

[0107] (25) When Force voltage = 2V, check whether the measured voltage is equal to 2V ± 2%;

[0108] (26) When Force voltage = 2.5V, check whether the measured voltage is equal to 2.5V ± 2%;

[0109] (27) When Force voltage = 3V, check whether the measured voltage is equal to 3V ± 2%;

[0110] (28) When Force voltage = 3.5V, check whether the measured voltage is equal to 3.5V ± 2%;

[0111] (29) When Force voltage = 4V, check whether the measured voltage is equal to 4V ± 2%;

[0112] (30) When Force voltage = 4.5V, check whether the measured voltage is equal to 4.5V ± 2%;

[0113] (31) When Force voltage = 5V, check whether the measured voltage is equal to 5V ± 2%;

[0114] (32) When Force voltage = 5.5V, check whether the measured voltage is equal to 5.5V ± 2%;

[0115] (33) When Force voltage = 6V, check whether the measured voltage is equal to 6V ± 2%;

[0116] (34) When Force voltage = 6.5V, check whether the measured voltage is equal to 6.5V ± 2%;

[0117] (35) When Force voltage = 7V, check whether the measured voltage is equal to 7V ± 2%;

[0118] (36) When Force voltage = 7.5V, check whether the measured voltage is equal to 7.5V ± 2%;

[0119] (37) When Force voltage = 8V, check whether the measured voltage is equal to 8V ± 2%;

[0120] (38) When Force voltage = 8.5V, check whether the measured voltage is equal to 8.5V ± 2%;

[0121] (39) When Force voltage = 9V, check whether the measured voltage is equal to 9V ± 2%;

[0122] (40) When Force voltage = 9.5V, check whether the measured voltage is equal to 9.5V ± 2%;

[0123] (41) When Force voltage = 10V, check whether the measured voltage is equal to 10V ± 2%.

[0124] In the example, when the maximum error is set to 50mV, since the test errors of each channel do not exceed the maximum value, the test results are all passed. For example, the maximum error voltage of channel 0 is about 14mV and the minimum is about 4mV; the maximum error voltage of channel 3 is about 30mV and the minimum is about 8mV.

[0125] However, when the accuracy requirement is higher, for example, when the maximum error value is set at 2mV, each channel of the PMU cannot meet the accuracy requirement, and PMU calibration is required.

[0126] In addition, the PMU test voltage range can be set to -10 to +12.5 V, and the PMU can be tested again, that is, the above steps (1) to (41) can be repeated to further observe whether the PMU meets the requirements.

[0127] After the test, if the error between the force voltage (ie, theoretical voltage value) and the tested voltage (ie, actual tested voltage value) is greater than 2%, the calibration function can be used to make the force voltage of the PMU equal to the measured voltage or within the error range.

[0128] Specifically, taking the calibration of a PMU (such as a PMU with AD5522 as the core) to meet the requirement of 2mV accuracy as an example, the process is as follows:

[0129] (1) Reduce the zero point error so that the zero point is as close to 0 as possible;

[0130] (2) Set the force voltage as low as possible;

[0131] (3) Measure the actual output voltage and compare it with the force voltage. The error of zero level can be obtained by using the force voltage minus the actual measured error.

[0132] (4) adding the calculated error to the error register, or subtracting the calculated error from the value of the error register;

[0133] (5) Reduce the gain error to make it as small as possible;

[0134] (6) Error in measuring zero level;

[0135] (7) Set the force voltage to the maximum value possible;

[0136] (8) Measure the actual output voltage and use the force voltage minus the actual measured error to get the gain error.

[0137] (9) subtracting the gain error from the gain error register by calculating a binary number equal to the gain error;

[0138] (10) The device is configured by writing control registers so that different functions can be set as needed;

[0139] (11) Calibrate the device to remove the errors and load the required calibration values ​​into the gain (M) and offset (C) registers.

[0140] After the PMU is calibrated, the errors of each channel are very small. For example, the maximum error of channel 3 is 0.525MV, that is, the maximum error is about 0.5mV, which well meets the accuracy requirement of 2mV.

[0141] In another example, the PMU is set to enter the FIMI (force current measure current) mode. The following example uses the PMU test current range of 0 to 50 mA, and the FIMI test is performed with a step of 1 mA and an error range of 2%. The test is performed according to the following process:

[0142] (1) When Force current = 0mA, check whether the measured current is equal to 0±2%;

[0143] (2) When Force current = 1mA, check whether the measured current is equal to 1±2%;

[0144] (3) When Force current = 2mA, check whether the measured current is equal to 2±2%;

[0145] (4) When Force current = 3mA, check whether the measured current is equal to 3±2%;

[0146] (5) When Force current = 4mA, check whether the measured current is equal to 4±2%;

[0147] (6) When Force current = 5mA, check whether the measured current is equal to 5±2%;

[0148] (7) When Force current = 10mA, check whether the measured current is equal to 10±2%;

[0149] (8) When Force current = 15mA, check whether the measured current is equal to 15±2%;

[0150] (9) When Force current = 20mA, check whether the measured current is equal to 15±2%;

[0151] (10) When Force current = 25mA, check whether the measured current is equal to 25±2%;

[0152] (11) When Force current = 30mA, check whether the measured current is equal to 30±2%;

[0153] (12) When Force current = 35mA, check whether the measured current is equal to 35±2%;

[0154] (13) When Force current = 40mA, check whether the measured current is equal to 40±2%;

[0155] (14) When Force current = 45mA, check whether the measured current is equal to 45±2%;

[0156] (15) When Force current = 50mA, check whether the measured current is equal to 50±2%.

[0157] After the test, if the error between the force current and the measured current is greater than 2%, the calibration function can be used to make the force current and the measured current equal, or within the error range.

[0158] The calibration process of AD5522 is shown as follows:

[0159] (1) In force current mode, write zero scale to the FIN DAC and measure the error between the external current and the internal current.

[0160] (2) Repeat the above steps, load the full scale to the FIN DAC, and calculate the error gain (M) and offset (C) values.

[0161] (3) Write the values ​​of error gain (M) and offset (C) into the gain register and offset register respectively;

[0162] (4) Repeat this process to find more suitable values ​​of M and C.

[0163] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0164] The above is only a specific implementation of the present application, but the protection scope of the present application 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 in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A precision measurement unit calibration circuit, characterized in that: include: Power supply circuit, controller, analog multiplexer, analog-to-digital conversion circuit and sampling resistor; The power supply circuit is used to provide corresponding working power to the controller, the analog multiplexer, the analog-to-digital conversion circuit and the precision measurement unit to be calibrated respectively after stabilizing the input power supply; The analog multiplexer includes a first group of multiplex switches and a second group of multiplex switches; wherein the common end of the first group of multiplex switches is electrically connected to the driving circuit of the precision measurement unit, the common end of the second group of multiplex switches is electrically connected to the sensing circuit of the precision measurement unit, the address end and the enable end of the first group of multiplex switches, and the address end and the enable end of the second group of multiplex switches are electrically connected to the controller respectively, and the multiplex channel end of the first group of multiplex switches is correspondingly connected to the multiplex channel end of the second group of multiplex switches and is electrically connected to the sampling resistor; The analog-to-digital conversion circuit is electrically connected to the measurement output terminal of the precision measurement unit and the first communication interface of the controller respectively, and is used to digitally convert the measurement output of the precision measurement unit and transmit the converted digital signal to the controller; The second communication interface of the controller is electrically connected to the communication interface of the precision measurement unit, and is used to configure the precision measurement unit to output a corresponding drive signal to the sampling resistor through the drive circuit, and to configure the precision measurement unit to obtain a corresponding sampling signal formed by the drive signal on the sampling resistor through the sensing circuit.

2. The precision measurement unit calibration circuit according to claim 1, characterized in that: The power supply circuit comprises: a first power supply circuit, a second power supply circuit and a third power supply circuit; The first power supply circuit is used to stabilize the input power supply and then provide the analog power supply positive voltage required for the operation of the analog circuit to the precision measurement unit, the second power supply circuit, the third power supply circuit, and the analog multiplexer respectively; The second power supply circuit is used to provide the analog power supply negative voltage required for the operation of the analog circuit to the precision measurement unit and the analog multiplexer respectively after stabilizing the working power supply provided by the first power supply circuit; The third power supply circuit is used to provide the digital power supply voltage required for the operation of the digital circuit to the precision measurement unit and the controller respectively after stabilizing the working power supply provided by the first power supply circuit.

3. The precision measurement unit calibration circuit according to claim 2, characterized in that: The first power supply circuit includes a Boost circuit, wherein the Boost circuit is used to output a first positive voltage as a simulated power supply positive voltage after boosting and stabilizing the input power supply; The second power supply circuit includes a Buck circuit, wherein the Buck circuit is used to output a first negative voltage as an analog power supply negative voltage after stabilizing the first positive voltage; The third power supply circuit includes a linear voltage stabilization circuit, wherein the linear voltage stabilization circuit is used to output a second positive voltage as a digital power supply voltage after voltage reduction and voltage stabilization according to the first positive voltage.

4. The precision measurement unit calibration circuit according to claim 3, characterized in that: The calibration range of the precision measurement unit includes -10V to 10V or -10V to 12.5V, the voltage value of the input power supply is 12V, the positive voltage of the analog power supply is 15V, the negative voltage of the analog power supply is -15V, and the digital power supply voltage is 3.3V.

5. The precision measurement unit calibration circuit according to claim 1, characterized in that: When the precision measurement unit includes a plurality of measurement channels, the precision measurement units share the analog-to-digital conversion circuit.

6. The precision measurement unit calibration circuit according to claim 1, characterized in that: The first group of multiplexing switches and the second group of multiplexing switches are both SP4T switches, and the sampling resistor includes a first resistor, a second resistor and a third resistor; wherein the first channel port of the first group of multiplexing switches and the first channel port of the second group of multiplexing switches are connected to a signal ground; The second channel port of the first group of multiplexing switches and the second channel port of the second group of multiplexing switches are connected to one end of the first resistor, and the other end of the first resistor is connected to the signal ground; The third channel port of the first group of multiplexing switches and the third channel port of the second group of multiplexing switches are connected to one end of the second resistor, and the other end of the second resistor is connected to the signal ground; The fourth channel port of the first group of multiplexing switches and the fourth channel port of the second group of multiplexing switches are connected to one end of the third resistor, and the other end of the third resistor is connected to the signal ground.

7. The precision measurement unit calibration circuit according to claim 1, characterized in that: The controller is a single-chip microcomputer, and the communication interface of the precision measurement unit includes a SIP interface; wherein the controller is electrically connected to the communication interface of the precision measurement unit, including: the GPIO of the single-chip microcomputer is electrically connected to the corresponding SIP interface of the precision measurement unit; And / or, the controller is further configured to load a new calibration value into a register of the precision measurement unit via the communication interface when it is determined that the error of the sampling signal deviating from the driving signal exceeds an error threshold.

8. The precision measurement unit calibration circuit according to any one of claims 1 to 7, characterized in that: The driving circuit of the precision measurement unit is also electrically connected to an external measurement device.

Images