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CN-122017712-A - Impedance calibration device and calibration method

CN122017712ACN 122017712 ACN122017712 ACN 122017712ACN-122017712-A

Abstract

The invention relates to the technical field of microelectronics and discloses an impedance calibration device and a calibration method, wherein the impedance calibration device comprises a circuit board, an impedance line and characteristic impedance, wherein a first contact is arranged on a copper surface of the circuit board; the impedance line is arranged on the circuit board, the second contact and the third contact are arranged on the impedance line, and the characteristic impedance is arranged at two ends of the impedance line. The differential impedance calibration is realized by pinning one signal of the probe at the second contact and the other signal at the third contact, the single-ended impedance calibration is realized by pinning one signal of the probe at the first contact and the other signal at the second contact or the third contact, and the impedance test of the internal impedance line of the board can be realized by one device realizing two operations of differential impedance calibration and single-ended impedance calibration. The impedance calibration device provided by the invention solves the problem that the impedance test calibration of the internal line of the board cannot be carried out in the board edge impedance line test mode in the prior art.

Inventors

  • ZHU ZHINING

Assignees

  • 南京测源科技有限公司

Dates

Publication Date
20260512
Application Date
20260409

Claims (9)

  1. 1. An impedance calibration apparatus, comprising: The circuit board (1), the copper surface of the circuit board (1) is provided with a first contact (4); The impedance line (2) is arranged on the circuit board (1), the impedance line (2) is provided with two sections which are oppositely arranged, and one ends of the two sections of the impedance line (2) which are close to each other are respectively provided with a second contact (5) and a third contact (6); And the characteristic impedance is respectively arranged at one end of the two sections of impedance lines (2) which are far away from each other.
  2. 2. Impedance calibration device according to claim 1, characterized in that a plurality of test areas (7) are provided on the circuit board (1), each test area (7) being provided with the impedance line (2) and the characteristic impedance, the characteristic impedance in at least two test areas (7) being set to different specification resistances.
  3. 3. Impedance calibration device according to claim 2, characterized in that the test areas (7) are arranged on the circuit board (1) in four, the characteristic impedances in the four test areas (7) are all set to different specification resistances, and the specification resistances of the characteristic impedances are set to 25-100 ohms.
  4. 4. Impedance calibration device according to claim 1, characterized in that the two impedance lines (2) are at least partially parallel and spaced apart, the spacing distance between the parallel parts of the two impedance lines (2) being 0.2 mm-6 mm.
  5. 5. Impedance calibration device according to claim 4, characterized in that the first contact (4) is arranged on the copper surface of the circuit board (1) enclosed inside two sections of the impedance line (2).
  6. 6. Impedance calibration device according to claim 4, characterized in that two sections of the impedance line (2) form a U-shaped structure, and the second contact (5) and the third contact (6) are arranged at the midpoint of the U-shaped structure formed by the impedance line (2).
  7. 7. The impedance calibration device according to any one of claims 1 to 6, wherein the characteristic impedance is provided as an air bar.
  8. 8. A calibration method employing the impedance calibration apparatus of any one of claims 1-7, comprising the steps of: differential impedance calibration, wherein one signal pin on a probe is contacted with a second contact (5) on the impedance line (2), and the other signal pin on the probe is contacted with a third contact (6) on the impedance line (2); and (3) single-ended impedance calibration, wherein one signal needle on the probe is contacted with a first contact (4) on the copper surface of the circuit board (1), and the other signal needle on the probe is contacted with a second contact (5) or a third contact (6) on the impedance line (2).
  9. 9. The calibration method according to claim 8, wherein the probe performs single-ended impedance calibration and differential impedance calibration on each test area (7) on the circuit board (1), the test result of each probe is collected as an original measurement value, and the original measurement value and a known standard value are combined to establish a calibration data pair, wherein the characteristic impedance adopts a standard air bar sample, and the known standard value is an impedance value formed by the characteristic impedance corresponding to the time of collecting the original measurement value; Taking the span of each section of 5 omega as a segmentation standard, and dividing the range of 10 omega-120 omega into a plurality of gears; Performing first-order linear least square fitting on each gear by using the calibration data points falling into the interval, and storing the obtained fitting result in a lookup table form; When the test value of the probe falls in the middle area of the gear interval, taking the compensation coefficient of the current gear, and inversely transforming to obtain a compensated impedance value; when the test value of the probe falls near the boundary of the gear interval, the compensation coefficients of two adjacent gears are taken, an interpolation compensation algorithm is adopted, the interpolation compensation coefficients are obtained according to weight interpolation, and the impedance value after compensation is obtained through inverse transformation.

Description

Impedance calibration device and calibration method Technical Field The invention relates to the technical field of microelectronics, in particular to an impedance calibration device and a calibration method. Background Impedance testing is a test method commonly used in the electrical engineering and electronics arts to evaluate the response of a circuit, device or system to an alternating current signal. Before impedance testing, the system error of the whole machine of the impedance testing machine is required to be calibrated, namely, the impedance testing machine measures an air rod with a certain resistance specification calibrated by a metering authentication mechanism, and supplements the whole machine of the impedance testing machine after obtaining the deviation value, so that the accuracy of the impedance testing is ensured. In the prior art, the calibration of the characteristic impedance of the PCB line still stays at the design impedance line of the board edge, and is manually tested by a worker, and the worker holds the test head to contact the test point. However, the deviation between the impedance value of the board internal line and the impedance value of the impedance line of the PCB board is large, and for a high-end PCB, it is required to perform an impedance test on the board internal line, so that the board edge impedance line test mode cannot meet the requirement. Disclosure of Invention The invention provides an impedance calibration device and a calibration method, which are used for solving the problem that an impedance test calibration cannot be carried out on an internal line of a board in a board edge impedance line test mode in the prior art. The invention provides an impedance calibration device which comprises a circuit board, an impedance line and characteristic impedance, wherein a first contact is arranged on a copper surface of the circuit board, the impedance line is arranged on the circuit board, the impedance line is provided with two sections which are oppositely arranged, one ends, close to each other, of the two sections of the impedance line are respectively provided with a second contact and a third contact, and one end, far away from each other, of the two sections of the impedance line is respectively provided with one characteristic impedance. The differential impedance calibration device has the advantages that when the differential impedance calibration device is used, differential impedance calibration is achieved by means of one signal pin of the probe at the second contact and the other signal pin at the third contact, differential impedance is the sum of specification resistance values of two characteristic impedances, single-ended impedance calibration is achieved by means of one signal pin of the probe at the first contact and the other signal pin at the second contact or the third contact, single-ended impedance calibration is achieved to be the specification resistance value of one characteristic impedance, and one device achieves two operations of differential impedance calibration and single-ended impedance calibration and can conduct impedance test calibration on internal lines of the board. The impedance calibration device provided by the invention solves the problem that the impedance test calibration of the internal line of the board cannot be carried out in the board edge impedance line test mode in the prior art. In an alternative implementation manner, a plurality of test areas are arranged on the circuit board, the impedance lines and the characteristic impedance are arranged in each test area, and the characteristic impedance in at least two test areas is set to be different specification resistance values. The device has the beneficial effects that different characteristic impedances are selected by the plurality of test areas, so that impedance calibration of multiple specification impedance values can be realized, and the application range of the device is improved. In an alternative implementation manner, the four test areas are arranged on the circuit board, the characteristic impedance in the four test areas is set to be different specification resistance values, and the specification resistance values of the characteristic impedance are set to be 25 ohms-100 ohms. The differential impedance calibration method has the advantages that characteristic impedance with different specification impedance values is arranged in four different test areas, differential impedance calibration and single-end impedance calibration with different specification impedance values can be formed, for example, the specification impedance values of the characteristic impedance in the four test areas are respectively 25 ohms, 50 ohms, 75 ohms and 100 ohms, when signals of the probe are pinned at the second contact and the third contact, the differential impedance is corresponding to 50 ohms, 100 ohms, 150 ohms and 200 ohms, and when signals of the probe are