An impedance matching test circuit board suitable for use in a crystal network analyzer

Abstract

The utility model provides a kind of impedance matching test circuit board suitable for crystal network analyzer, it is related to electronic component testing technical field, the circuit board includes: input impedance conversion network, the input end of input impedance conversion network is used to connect the first port of network analyzer, input impedance conversion network is used to convert the transmission line impedance of network analyzer into preset low impedance value;Output impedance conversion network, the output end of output impedance conversion network is used to connect the second port of network analyzer, output impedance conversion network is used to convert back transmission line impedance from preset low impedance value;Test interface, test interface includes first test probe and second test probe, first test probe connects the output end of input impedance conversion network, second test probe connects the input end of output impedance conversion network, and first test probe and second test probe are respectively used to connect the two functional pins of crystal resonator.

Description

Technical Field

[0001] This utility model relates to the field of electronic component testing technology, specifically to an impedance matching test circuit board suitable for crystal network analyzers. Background Technology

[0002] Quartz crystal resonators, as electronic components exhibiting piezoelectric effect, are widely used in various electronic devices due to their high Q value, excellent resonant frequency stability, moderate processing difficulty, and controllable cost. They are particularly prevalent in oscillator circuits as the core resonant source, providing a stable clock frequency reference for the system. With the advancement of electronic technology towards higher precision and reliability, the impedance matching performance between the crystal resonator and the oscillation circuit has an increasingly significant impact on its operational stability. Impedance mismatch between the two will lead to severe reflections during signal transmission, reduced energy transmission efficiency, and even frequency drift and phase noise degradation, directly affecting the oscillator's performance.

[0003] In practical applications, oscillator circuits are mostly implemented using highly integrated IC chips, whose internal structures and parameters are usually fixed, making it difficult to flexibly adjust them for different crystal resonators. Therefore, in the crystal resonator production screening process, how to accurately select crystal resonators with highly matched impedance characteristics to the target oscillator circuit has become a key technical issue to ensure the stability of the final product. Currently, the industry mainly relies on precision instruments such as network analyzers to test the impedance characteristics of crystal resonators. The network analyzer measures parameters such as the resonant frequency and impedance characteristics of the crystal resonator under test (DUT) to evaluate its matching degree with the target circuit.

[0004] However, in existing testing schemes, the transmission lines of network analyzers typically employ a standard characteristic impedance design, while the actual resonant impedance of the crystal resonator under test often deviates from the characteristic impedance of the transmission line. When the termination impedance of the crystal resonator under test does not match the characteristic impedance of the network analyzer's transmission line, the signal will be strongly reflected at the interface between the transmission line and the device under test, causing the network analyzer to be unable to accurately obtain the true impedance characteristic parameters of the device under test, severely affecting the reliability of the test results. In addition, traditional test circuits are not optimized for the impedance distribution characteristics of crystal resonators, making it difficult to ensure that the termination impedance of the device under test conforms to its resonant characteristics while achieving impedance matching with the transmission line of the network analyzer, resulting in problems such as low test efficiency and insufficient screening accuracy. Utility Model Content

[0005] In view of the above problems, this utility model provides an impedance matching test circuit board suitable for a crystal network analyzer. The impedance matching test circuit board suitable for a crystal network analyzer includes: an input impedance transformation network, the input end of which is used to connect to a first port of the network analyzer, and the input impedance transformation network is used to transform the transmission line impedance of the network analyzer to a preset low impedance value.

[0006] An output impedance transformation network is provided, the output of which is connected to the second port of a network analyzer. The output impedance transformation network is used to transform the preset low impedance value back to the transmission line impedance.

[0007] The test interface includes a first test probe and a second test probe. The first test probe is connected to the output terminal of the input impedance transformation network, and the second test probe is connected to the input terminal of the output impedance transformation network. The first test probe and the second test probe are respectively used to connect to two functional pins of the crystal resonator.

[0008] In one possible implementation, the transmission line impedance ranges from 49.5Ω to 50.5Ω, and the low impedance value ranges from 12.3Ω to 12.7Ω.

[0009] In one possible implementation, the transmission line impedance is 50Ω, and the low impedance value is 12.5Ω.

[0010] In one possible implementation, both the input impedance transformation network and the output impedance transformation network are π-type resistor networks.

[0011] In one possible implementation, the input impedance transformation network includes a first resistor, a second resistor, and a third resistor, wherein:

[0012] The first end of the first resistor is connected to the first end of the second resistor, and both are connected to the input terminal;

[0013] The second end of the first resistor is connected to the first end of the third resistor, and both are connected to ground;

[0014] The second end of the second resistor is connected to the second end of the third resistor, and together they are connected to the first end of the test interface.

[0015] In one possible implementation, the output impedance transformation network includes a fourth resistor, a fifth resistor, and a sixth resistor, wherein:

[0016] The first end of the fourth resistor is connected to the first end of the fifth resistor, and together they are connected to the second end of the test interface;

[0017] The second end of the fourth resistor is connected to the first end of the sixth resistor, and both are connected to ground;

[0018] The second end of the fifth resistor is connected to the second end of the sixth resistor, and together they are connected to the output terminal.

[0019] In one possible implementation, the impedance matching test circuit board for a crystal network analyzer further includes an input port and an output port for connecting the transmission line of the network analyzer, wherein the input port and the output port are respectively connected to the input terminal of the input impedance transformation network and the output terminal of the output impedance transformation network.

[0020] The above-described one or more technical solutions in the embodiments of this application have at least one or more of the following technical effects:

[0021] This invention provides an impedance matching test circuit board suitable for crystal network analyzers. Through an input impedance transformation network, the high impedance characteristics of the network analyzer's transmission line are adapted to a low impedance state that better matches the resonant characteristics of the crystal resonator under test. This avoids signal reflection loss caused by excessive impedance differences at both ends, ensuring stable termination conditions for the device under test during testing. The output impedance transformation network further rematches this low impedance state to the high impedance requirements of the network analyzer's transmission line, achieving bidirectional impedance coordination between the device under test and the test system. This bidirectional impedance transformation mechanism effectively reduces energy reflection at the interface, enabling the network analyzer to more accurately obtain key parameters such as the true resonant frequency and impedance characteristics of the crystal resonator under test. This significantly improves the selection accuracy and testing efficiency of crystal resonators, providing reliable technical support for device selection in high-reliability oscillation circuits.

[0022] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more obvious and understandable, specific embodiments of this utility model are given below. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the module structure of the impedance matching test circuit board for a crystal network analyzer in an embodiment of this utility model;

[0025] Figure 2 This is a schematic diagram of the impedance matching test circuit board for a crystal network analyzer in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the impedance matching test circuit board for a crystal network analyzer according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 100, input impedance transformation network; 200, network analyzer; 300, test interface; 310, first test probe; 320, second test probe; 400, output impedance transformation network; 500, input port; 600, output port. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0029] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this invention as detailed in the appended claims.

[0030] The overall concept of the technical solution provided by this utility model is as follows:

[0031] Please see Figures 1 to 3 The π-type impedance matching test circuit board for the Crystal Network Analyzer 200 includes:

[0032] An input impedance transformation network 100 is used to connect to the first port of the network analyzer 200. The input impedance transformation network 100 transforms the transmission line impedance of the network analyzer 200 to a preset low impedance value. This transformation process aims to solve the impedance mismatch problem between the crystal resonator under test and the transmission line of the network analyzer 200, thereby reducing signal reflection and improving test accuracy and reliability. More specifically, the input impedance transformation network 100 is typically composed of impedance transformation elements. For example, precise impedance matching can be achieved through series and parallel resistors, and complex impedance transformations can be achieved using π-type or T-type resistor networks.

[0033] The output impedance transformation network 400 is used to connect to the second port of the network analyzer 200. The output impedance transformation network 400 transforms a preset low impedance value back to the transmission line impedance. Similar to the input impedance transformation network 100, the output impedance transformation network 400 is typically composed of impedance transformation elements. For example, precise impedance matching can be achieved through series and parallel resistors, and complex impedance transformations can be achieved using π-type or T-type resistor networks.

[0034] The test interface 300 includes a first test probe 310 and a second test probe 320. The first test probe 310 is connected to the output terminal of the input impedance transformation network 100, and the second test probe 320 is connected to the input terminal of the output impedance transformation network 400. The first test probe 310 and the second test probe 320 are respectively used to connect two functional pins of the crystal resonator. The test interface 300 is used to reliably connect the output terminal of the input impedance transformation network 100 and the input terminal of the output impedance transformation network 400 to the two functional pins of the crystal resonator under test, ensuring that the signal can be transmitted efficiently and stably.

[0035] More specifically, a crystal resonator typically has two pins, one for input signals and one for output signals. The signal from the network analyzer 200 first enters the input impedance transformation network 100. After impedance transformation, the signal is transmitted through the first test probe 310 to the input pin of the crystal resonator under test. The processed signal from the crystal resonator under test is transmitted through its output pin to the second test probe 320. After impedance transformation through the output impedance transformation network 400, the signal returns to the network analyzer 200. The first test probe 310 and the second test probe 320 are typically made of highly conductive materials, such as gold-copper alloys, to ensure good electrical contact and mechanical durability. The first test probe 310 and the second test probe 320 are typically designed with a spring-loaded structure to provide stable contact force and good contact reliability.

[0036] The output impedance transformation network 400 is used to transform the preset low impedance value output by the test interface 300 back to the characteristic impedance of the transmission line of the network analyzer 200. This process ensures that the signal can return to the network analyzer 200 with an impedance value that matches the transmission line after passing through the crystal resonator under test, thereby achieving bidirectional impedance matching, reducing signal reflection, and improving test accuracy and reliability.

[0037] The input impedance transformation network 100 adapts the high impedance characteristics of the transmission line of the network analyzer 200 to a low impedance state that better matches the resonance characteristics of the crystal resonator under test, avoiding signal reflection loss caused by excessive impedance difference between the two ends and ensuring that the device under test maintains stable termination conditions during the test. The output impedance transformation network 400 further rematches this low impedance state to the high impedance requirements of the transmission line of the network analyzer 200, realizing bidirectional impedance coordination between the device under test and the test system. This bidirectional impedance transformation mechanism effectively reduces energy reflection at the interface, enabling the network analyzer 200 to more accurately obtain the true resonant frequency, impedance characteristics and other key parameters of the crystal resonator under test, significantly improving the selection accuracy and testing efficiency of the crystal resonator, and providing reliable technical support for the selection of devices for high-reliability oscillation circuits.

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0039] Furthermore, the transmission line impedance ranges from 49.5Ω to 50.5Ω, with lower impedance values ​​ranging from 12.3Ω to 12.7Ω. In high-frequency circuits and radio frequency (RF) applications, 50Ω is the most commonly used standard transmission line characteristic impedance. This standard impedance value is widely adopted in many RF and microwave applications because it provides a good balance between power delivery and signal integrity. Choosing 12.3Ω to 12.7Ω as the lower impedance range, which is closer to the median resonant impedance of various crystal resonators, helps to achieve better impedance matching, reduce signal reflection, and improve measurement accuracy.

[0040] Preferably, the transmission line impedance is 50Ω, with a low impedance value of 12.5Ω. The 12.5Ω impedance value is closer to the median resonant impedance of many crystal resonators, meaning that in most cases, the impedance transformation network can effectively transform the 50Ω transmission line impedance of the network analyzer 200 to a value close to the resonant impedance of the crystal resonator, thereby achieving better impedance matching.

[0041] Furthermore, both the input impedance transformation network 100 and the output impedance transformation network 400 are π-type resistor networks. A π-type resistor network is a common impedance matching network, typically consisting of two parallel resistors located at the input and output terminals respectively, and a series resistor connected between the two parallel resistors. A π-type resistor network can achieve precise impedance matching by appropriately selecting resistor values, making it suitable for applications requiring high matching accuracy.

[0042] Please see Figure 2 The input impedance transformation network 100 includes a first resistor R1, a second resistor R2, and a third resistor R3, wherein:

[0043] The first end of the first resistor R1 is connected to the first end of the second resistor R2, and they are both connected to the input terminal.

[0044] The second terminal of the first resistor R1 is connected to the first terminal of the third resistor R3, and both are connected to ground;

[0045] The second end of the second resistor R2 is connected to the second end of the third resistor R3, and together they are connected to the first end of the test interface 300.

[0046] For example, the sweep signal from the network analyzer 200 enters the input impedance transformation network 100 through a 50Ω transmission line. The first resistor R1, the second resistor R2, and the third resistor R3 form a π-type impedance transformation network, which transforms the 50Ω impedance into a 12.5Ω impedance. The signal after impedance transformation is transmitted to the first functional pin of the crystal resonator under test through the first test probe 310 of the test interface 300.

[0047] Please see Figure 2 The output impedance transformation network 400 includes a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6, wherein:

[0048] The first end of the fourth resistor R4 is connected to the first end of the fifth resistor R5, and together they are connected to the second end of the test interface 300.

[0049] The second terminal of the fourth resistor R4 is connected to the first terminal of the sixth resistor R6, and together they are connected to ground;

[0050] The second end of the fifth resistor R5 is connected to the second end of the sixth resistor R6, and together they are connected to the output terminal.

[0051] For example, the sweep frequency signal enters through the first functional pin of the crystal resonator under test, resonates with the crystal resonator, and then exits from the second functional pin of the crystal resonator. It then enters the output impedance transformation network 400 through the second terminal of the test interface 300. The fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 form a π-type impedance transformation network, which transforms the 12.5Ω impedance into a 50Ω impedance. The signal after impedance transformation is transmitted to the second port of the network analyzer 200 through the output terminal.

[0052] Please see Figure 3 The π-type impedance matching test circuit board for the crystal network analyzer 200 also includes an input port 500 and an output port 600 for connecting transmission lines to the network analyzer 200. Input port 500 and output port 600 are respectively connected to the input terminal of the input impedance transformation network 100 and the output terminal of the output impedance transformation network 400. Input port 500 and output port 600 are used to connect to the first and second ports of the network analyzer 200 via transmission lines. Input port 500 and output port 600 can use coaxial 50Ω connectors, such as SMA or BNC.

[0053] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0054] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this utility model without departing from the spirit and scope of the embodiments of this utility model. Therefore, if these modifications and variations to the embodiments of this utility model fall within the scope of the claims of this utility model and their equivalents, then this utility model also intends to include these modifications and variations.

Claims

1. An impedance matching test circuit board suitable for a crystal network analyzer, characterized in that, include: An input impedance transformation network is provided, wherein the input terminal of the input impedance transformation network is used to connect to the first port of the network analyzer, and the input impedance transformation network is used to transform the transmission line impedance of the network analyzer to a preset low impedance value. An output impedance transformation network is provided, the output of which is connected to the second port of a network analyzer. The output impedance transformation network is used to transform the preset low impedance value back to the transmission line impedance. The test interface includes a first test probe and a second test probe. The first test probe is connected to the output terminal of the input impedance transformation network, and the second test probe is connected to the input terminal of the output impedance transformation network. The first test probe and the second test probe are respectively used to connect to two functional pins of the crystal resonator.

2. The impedance matching test circuit board for a crystal network analyzer according to claim 1, characterized in that, The transmission line impedance ranges from 49.5Ω to 50.5Ω, and the low impedance ranges from 12.3Ω to 12.7Ω.

3. The impedance matching test circuit board for a crystal network analyzer according to claim 2, characterized in that, The transmission line impedance is 50Ω, and the low impedance value is 12.5Ω.

4. The impedance matching test circuit board for a crystal network analyzer according to claim 1, characterized in that, Both the input impedance transformation network and the output impedance transformation network are π-type resistor networks.

5. The impedance matching test circuit board for a crystal network analyzer according to claim 1, characterized in that, The input impedance transformation network includes a first resistor, a second resistor, and a third resistor, wherein: The first end of the first resistor is connected to the first end of the second resistor, and both are connected to the input terminal; The second end of the first resistor is connected to the first end of the third resistor, and both are connected to ground; The second end of the second resistor is connected to the second end of the third resistor, and together they are connected to the first end of the test interface.

6. The impedance matching test circuit board for a crystal network analyzer according to claim 1, characterized in that, The output impedance transformation network includes a fourth resistor, a fifth resistor, and a sixth resistor, wherein: The first end of the fourth resistor is connected to the first end of the fifth resistor, and together they are connected to the second end of the test interface; The second end of the fourth resistor is connected to the first end of the sixth resistor, and both are connected to ground; The second end of the fifth resistor is connected to the second end of the sixth resistor, and together they are connected to the output terminal.

7. An impedance matching test circuit board suitable for a crystal network analyzer according to any one of claims 1-6, characterized in that, It also includes an input port and an output port for connecting the transmission line of the network analyzer, the input port and the output port being respectively connected to the input end of the input impedance transformation network and the output end of the output impedance transformation network.

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