TWI648544B - Test structure for testing RF components - Google Patents

Abstract

A test structure for testing radio frequency components is provided with a first impedance component at the end of a transmission line of a test device, so that when testing a radio frequency component, the first impedance component generates a great impedance, thereby suppressing the transmission line Current and radiation generated at the ends.

Description

Test structure for testing radio frequency components

The invention relates to a test structure, especially a test structure for testing radio frequency components.

With the development of the electronics industry towards light, thin, short, small, high speed, and high density, wireless communication technology has been widely used in various consumer electronic products to facilitate receiving or sending various wireless signals, such as global mobile communications Global System for Mobile Communications (GMS), Wireless LAN (WLAN), Global Positioning System (GPS), Bluetooth, Bluetooth, Digital Video Broadcasting- Handheld (abbreviated as DVB-H), etc., so conventional wireless communication products are equipped with antenna modules that can receive or transmit radio frequency (Radio frequency, abbreviated as RF) signals.

Since the antenna is an important component of signal transmission and reception in wireless communication products, the transmission and reception power of the antenna needs to be tested in the production process of wireless communication products.

As shown in Figure 1, in the conventional test equipment for detecting antennas, its The test equipment connects a transmission line 1 through the signal probe 12a and the ground probe 12b to the corresponding signal test pad 9a and ground test pad 9b. Specifically, the transmission line 1 covers the signal port 11a with an insulator 10, and the signal port 11a extends out of the insulator 10 to form the signal probe 12a, and a ground layer 11b is formed outside the insulator 10 to allow the ground detection The needle 12b is provided on the ground layer 11b. Moreover, the radio frequency element 9 as an antenna is connected to the signal test pad 9a with its antenna body 90, but not connected to the ground test pads 9b.

When performing a test operation, the test equipment provides an alternating current I to the antenna body 90 via the signal port 11a and the signal test pad 9a, and emits radiation a to ambient air to allow the test equipment to receive the radiation The signal of a is used to judge the transmit and receive power of the radio frequency element 9.

However, when an AC current passes through the signal port 11a, due to the electrical reflow characteristics, a reverse AC current I 'will be generated on the surface of the ground layer 11b, and the reverse AC current I' will flow through the ground probe 12b To the ground test pad 9b, so that the ground layer 11b cannot cover the entire current, that is, the reverse AC current I 'exists on the outer surface of the transmission line 1, so the reverse AC current I' will produce radiation b, so The test equipment will not only receive the signal of the expected radiation a, but also the signal of the undesired radiation b generated by the outer surface of the transmission line 1, so that the test equipment will be interfered by the undesired radiation b when receiving the signal And cause misjudgment or test error.

Therefore, how to overcome the problems in the conventional technology has become an urgent problem to be solved.

In view of the above-mentioned lack of conventional technology, the present invention discloses a method for measuring Test the test structure of the radio frequency component, and the radio frequency component is provided with a test part. The test structure includes: a transmission line, the end of which has a plurality of external ports, and an insulator that isolates each of the external ports A probe device, so that the probe device is electrically connected to the testing part of the radio frequency element; and a first impedance device is provided outside the end of the transmission line, wherein the first impedance device includes a conductive part and an insulating part The insulating portion contacts the outside of the end of the transmission line, and the conductive portion is provided outside the insulating portion and electrically connects the transmission line.

In the aforementioned test structure, the transmission line is a cable or line configured on a test device.

In the aforementioned test structure, the first impedance element is a ring body.

In the aforementioned test structure, the length of the insulating portion is a quarter of the wavelength of the electromagnetic wave generated by the signal frequency of the radio frequency element.

In the aforementioned test structure, it further includes at least one second impedance element, which is disposed outside the first impedance element. For example, the second impedance element is a ring. Furthermore, the second impedance element includes a conductive portion and an insulating portion, the insulating portion contacts the outer side of the first impedance element, and the conductive portion is disposed on the outer side of the insulating portion and is electrically connected to the first impedance element With that transmission line. Further, the length of the insulating portion corresponds to the signal frequency of the radio frequency element.

It can be seen from the above that the test structure of the present invention is mainly provided by the first impedance member outside the end of the transmission line, so that when the test structure tests the RF element, the first impedance member has a maximum impedance, so it can be The current and radiation generated at the external port (or ground layer) outside the transmission line are suppressed.

1,2a‧‧‧Transmission line

10,20‧‧‧Insulator

11a‧‧‧Signal port

11b‧‧‧Ground layer

12a‧‧‧Signal probe

12b‧‧‧Ground probe

2,3‧‧‧Test structure

20a‧‧‧First end

20b‧‧‧Second end face

21a, 21b‧‧‧External port

22a, 22b‧‧‧probe

23‧‧‧The first impedance piece

23a‧‧‧First Conducting Department

23b‧‧‧First Insulation Department

31,32‧‧‧The second impedance piece

31a, 32a‧‧‧Second Conducting Department

31b, 32b‧‧‧Second Insulation Department

33‧‧‧Guide connector

9‧‧‧RF components

9a‧‧‧Signal test pad

9b‧‧‧Ground test pad

90‧‧‧ Antenna body

L, L0, L1, L2 ‧‧‧ length

S1‧‧‧First end

S2‧‧‧Second end

a, b‧‧‧radiation

I, I’‧‧‧ current

A1, A2, A3‧‧‧curve

Figure 1 is a schematic cross-sectional view of a transmission line of a conventional test device when in use; Figure 2 is a schematic cross-sectional schematic view of the first embodiment of the test structure of the present invention when in use; Figure 2 'is Figure 2 is a circuit diagram; Figure 3 is a schematic cross-sectional view of the second embodiment of the test structure of the present invention when in use; and Figure 4 is the radiant energy generated by the transmission lines of Figures 1, 2 and 3 Of the graph.

The following describes the implementation of the present invention by specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

It should be noted that the structure, ratio, size, etc. shown in the drawings of this specification are only used to match the content disclosed in the specification, for those who are familiar with this skill to understand and read, not to limit the implementation of the present invention The limited conditions do not have technical significance. Any modification of structure, change of proportional relationship or adjustment of size should still fall within the scope of the invention without affecting the efficacy and the purpose of the invention. The technical content disclosed by the invention can be covered. At the same time, the terms such as "outer side", "center", "first", "second" and "one" cited in this specification are only for the convenience of description, not for limiting the present invention. The scope of implementation, the change or adjustment of its relative relationship, without substantial changes in the technical content, shall also be regarded as the scope of the invention.

FIG. 2 is a schematic cross-sectional view of the first embodiment of the test structure 2 of the present invention. As shown in FIG. 2, the test structure 2 includes: a transmission line 2 a and a first impedance element 23.

In this embodiment, the test structure 2 is used to test a radio frequency element 9, such as an antenna structure. For example, the radio frequency element 9 is configured on an electronic device such as a smart phone (not shown), which includes an antenna body 90 and a plurality of electrical test pads (such as signal test) that can transmit signals to the antenna body 90 The pad 9a and the ground test pad 9b) are used as a test part, wherein the antenna body 90 is connected to the signal test pad 9a, but not connected to the ground test pad 9b.

The transmission line 2a is a cable or line arranged on a test device (not shown).

In this embodiment, the transmission line 2a has opposite first and second ends S1, S2, wherein the first end S1 is configured with a plurality of external ports 21a, 21b, and each of the external ports 21a, 21b There is an insulator 20 for isolation, and the second end S2 is installed on the test equipment. For example, one of the external ports 21a is located on the central axis of the transmission line 2a as a signal port, and the other external port 21b is located on the outer surface of the insulator 20 as a ground port. It should be understood that the outer outer port 21b can be regarded as an integrally formed surface layer, such as a metal sheet twisted into a tube, a metal layer plated on the insulator 20, and the like.

Furthermore, a probe element 22a, 22b is arranged on one side of each of the external ports 21a, 21b to contact and electrically connect the electrical test pad of the radio frequency element 9.

The first impedance element 23 is disposed outside the first end S1 of the transmission line 2a and electrically connected to the transmission line 2a.

In this embodiment, the first impedance element 23 is a ring body, such as a collar, to fit outside the first end S1.

Furthermore, the first impedance element 23 includes a first conductive portion 23a and a first insulating portion 23b, the first insulating portion 23b is sleeved outside the first end S1 of the transmission line 2a, and the first The conductive portion 23a is electrically connected to the transmission line 2a. For example, the first insulating portion 23b is located in the inner ring to contact the outer outer port 21b, and the first insulating portion 23b has opposite first end surface 20a and second end surface 20b. The probe pieces 22a, 22b are The first end surface 20a protrudes, and the transmission line 2a protrudes out of the second end surface 20b. On the other hand, the first conductive portion 23a is located on the outer ring and extends to the second end surface 20b of the first insulating portion 23b to contact the outer outer port 21b.

In addition, the length L of the first insulating portion 23b is a quarter of the wavelength λ (¼λ) of the electromagnetic wave generated by the signal frequency of the radio frequency element 9.

When the test structure 2 is used to test the radio frequency element 9, the probe pieces 22a, 22b are correspondingly contacted with the electrical test pads, so that the signal AC current provided by the test equipment passes through the central external port 21a of the transmission line 2a And the signal test pad 9a to the antenna body 90, so that the antenna body 90 emits radiation a into the ambient air, so that the test equipment receives the signal of the radiation a, thereby judging the transceiver power of the radio frequency element 9.

Therefore, if the signal bandwidth of the radio frequency element 9 is a single frequency, the design of the first impedance element 23 of the test structure 2 of the present invention can overcome the problem of test errors caused by unexpected radiation generated by the conventional technology. Specifically, with the circuit diagram shown in FIG. 2 'and the following transmission line impedance conversion formula:

Where V _S is the voltage supplied by the test equipment, the input impedance Z _in of the transmission line 2a is regarded as the impedance input from the resistor Z _S shown in FIG. 2 ', and Z _L is the terminal impedance of the transmission line 2a, Z ₀ is the characteristic impedance of the transmission line 2a, and β1 is related to the length of the transmission line 2a. When the length L of the transmission line 2a corresponding to the first insulating portion 23b is ¼ wavelength λ of the electromagnetic wave generated by the signal frequency of the radio frequency element 9, βl is equal to 90 degrees, tan ( βl ) is infinite, and when setting Z _L When = 0, Z _in is infinite (that is, the input impedance is infinite). Therefore, at a position about ¼ wavelength λ of the electromagnetic wave from the probe member 22b (that is, the length L of the first insulating portion 23b), the first conductive portion 23a contacts the outer outer port 21b to make the first conductive There is a short circuit between the portion 23a and the outer outer port 21b (or ground layer), so that the first end surface 20a of the first insulating portion 23b has a great impedance, which can suppress the current generated on the outer outer port 21b (or ground layer) and radiation.

FIG. 3 is a schematic cross-sectional view of the second embodiment of the test structure 3 of the present invention. The difference between this embodiment and the first embodiment is that a plurality of impedance members (ferrules) are added at the end of the transmission line, and the other structural configurations are substantially the same. Therefore, only the differences will be described below, and the similarities will not be repeated.

As shown in FIG. 3, the test structure 3 further includes second impedance members 31, 32, which are disposed outside the first impedance member 23 and electrically connected to the transmission line 2a. In this embodiment, two second impedance members 31, 32 are used for description. In fact, according to actual needs, additional settings may be added to the outside of the first impedance member 23 to One less (one or more) second impedance pieces.

In this embodiment, each of the second impedance members 31, 32 is a ring body, such as a collar, to fit outside the first impedance member 23, and the structure of each of the second impedance members 31, 32 and the The first impedance member 23 is substantially the same.

Furthermore, each of the second impedance elements 31, 32 includes a second conductive portion 31a, 32a and a second insulating portion 31b, 32b, and the second conductive portion 31a, 32a is electrically connected to the transmission line 2a. For example, the second insulating portions 31b, 32b are located in the inner ring, and the second conductive portions 31a, 32a are located in the outer ring, and a guide 33 is formed at the end surface to contact the second conductive portions 31a, 32a, The first conductive portion 23a and the outer outer port 21b.

When the test structure 3 is used to test the radio frequency element 9, the probe pieces 22a, 22b are correspondingly contacted with the electrical test pads, so that the signal AC current provided by the test structure 3 is externally connected through the center located on the axis The port 21a flows to the antenna body 90, so that the antenna body 90 emits the radiation a into the ambient air, so that the test equipment receives the signal of the radiation a, thereby judging the transmission and reception power of the RF element 9.

In this embodiment, if the signal bandwidth of the RF element 9 is 5G signal bandwidth or multiple frequencies, the electromagnetic waves are distributed at different frequencies (such as the signal bandwidth of 5G in 28GHz and in the range of 2GHz) at the same time The transmitted signal will be distributed in the frequency band from 27GHz to 29GHz. Therefore, the multi-loop design of the multiple impedance elements of the test structure 3 of the present invention (for example, including the first impedance element 23 and the second impedance elements 31, 32) In order to increase the impedance on the first end surface 20a of the first insulating portion 23b, it can suppress the current and radiation generated at the outer port 21b (or ground layer), which can overcome the conventional technology Unexpected radiation caused the test error.

Furthermore, the size of the second impedance element 31, 32 corresponds to the signal bandwidth of the radio frequency element 9. Specifically, with the graph shown in Figure 4 and the following formula: L (cm) = 22.5 / (f.√ε), where Figure 4 shows the curve A1 of the radiant energy measured by the conventional transmission line , The curve A2 of the radiant energy measured by the transmission line 2a of Figure 2, and the curve A3 of the radiant energy measured by the transmission line 2a of Figure 3, and the frequency f of the above formula (as shown in Figure 4 The frequencies f1, f0, and f2) are defined by the 5G bandwidth specification, and the length of the insulating portion relative to the first impedance member 23 (L in the above formula) can be defined as L0 and two second impedances as shown in FIG. 3 The length of the insulating portion of the pieces 31, 32 (L of the above formula) can be defined as L1 and L2 as shown in Figure 3, and ε is the dielectric constant of the insulating portion. Therefore, if the signal frequency f0 = 28 corresponding to the first impedance element 23 is close to 27, and the signal frequency f2 corresponding to the second impedance element 31 is close to 27, and the signal frequency f2 corresponding to the second impedance element 32 is close to 29, When the electric constant is 2, the length L0 = 0.568cm, the length L1 = 0.589cm and the length L2 = 0.548cm.

In summary, the test structure of the present invention is designed to increase the impedance of the end of the transmission line through the design of the impedance element to avoid the current and radiation generated on the surface of the transmission line. Therefore, compared with the conventional technology, the present invention The test structure can avoid undesired radiation signal interference when performing antenna testing, thus effectively reducing the interference factors, and thereby improving the measurement quality to improve the accuracy of the test results.

The above embodiments are used to exemplify the principles and effects of the present invention, rather than to limit the present invention. Anyone who is familiar with this skill can modify the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention should be as listed in the scope of patent application mentioned later.

Claims (8)

A test structure for testing a radio frequency element, and the radio frequency element is provided with a test part, the test structure includes: a transmission line, the end of which has a plurality of external ports and an insulator for isolating each external port, and the external port is connected A probe device is configured to electrically connect the probe device to the test portion of the radio frequency element; and a first impedance element is disposed outside the end of the transmission line, wherein the first impedance element includes a conductive portion and An insulating portion, the insulating portion contacts the outside of the end of the transmission line, and the conductive portion is disposed outside the insulating portion and is electrically connected to the transmission line. The test structure as described in item 1 of the patent application scope, wherein the transmission line is a cable or line arranged on a test device. The test structure as described in item 1 of the patent application scope, wherein the first impedance member is a ring body. The test structure as described in item 1 of the patent application scope, wherein the length of the insulating portion is a quarter of the wavelength of the electromagnetic wave generated by the signal frequency of the radio frequency element. The test structure as described in item 1 of the patent application scope further includes at least one second impedance element, which is disposed outside the first impedance element. The test structure as described in item 5 of the patent application scope, wherein the second impedance element is a ring body. The test structure as described in item 5 of the patent application scope, wherein the second impedance element includes a conductive portion and an insulation portion, the insulation portion contacts the outer side of the first impedance element, and the conductive portion is provided on the insulation The outer side of the part is electrically connected to the first impedance element and the transmission line. The test structure as described in item 7 of the patent application scope, wherein the length of the insulating portion corresponds to the signal frequency of the radio frequency component.