CN212727037U

CN212727037U - Tuning circuit, PCB (printed Circuit Board) and equipment for radio frequency signal test

Info

Publication number: CN212727037U
Application number: CN202021757804.3U
Authority: CN
Inventors: 刘好; 唐锡辉; 左达恒
Original assignee: Shenzhen Heyi Testing Technology Co ltd
Current assignee: Shenzhen Heyi Testing Technology Co ltd
Priority date: 2020-08-19
Filing date: 2020-08-19
Publication date: 2021-03-16
Anticipated expiration: 2030-08-19

Abstract

The utility model relates to a tuning circuit, a PCB and a device for testing radio frequency signals, which are used for adjusting matching impedance to match with the impedance of a radio frequency circuit, and comprise a variable capacitance inductance module and a control module; one end of the variable capacitance inductance module is coupled with a test point of the radio frequency circuit to be tested, and the other end of the variable capacitance inductance module is coupled with an external radio frequency signal test instrument; after the control module sends a control signal to the variable capacitance inductance module, the variable capacitance inductance module adjusts the matching impedance to be matched with the impedance of the radio frequency circuit; one end of the variable capacitance inductance module is connected to an antenna elastic sheet of the radio frequency circuit through a radio frequency test probe, the control module adjusts the matching impedance of the variable capacitance inductance module to enable the matching impedance to be matched with the impedance of the radio frequency circuit, meanwhile, the echo detection module can test and detect the echo loss, whether the matching impedance is matched in place or not is judged according to the echo loss until the matching impedance is matched with the impedance in the radio frequency circuit, and the test result is rigorous.

Description

Tuning circuit, PCB (printed Circuit Board) and equipment for radio frequency signal test

Technical Field

The utility model relates to a radio frequency signal tests technical field, especially relates to a tuned circuit, PCB board and equipment of radio frequency signal test.

Background

In recent years, along with the continuous development of communication technology, the popularity of wireless products is higher and higher, the number of wireless products produced globally every year is also increasing, and the production and the life of people are more and more convenient. Wireless products (represented by mobile phones) mainly refer to communication signals with a frequency range of 300kHz to 300GHz, which are also called radio frequency signals. In order to ensure the quality of the radio frequency signal on the main board of the wireless product so as to meet a series of most basic wireless communication requirements of the wireless product, a board-level radio frequency test is usually performed on a radio frequency chip on the main board.

The traditional board-level radio frequency test scheme is that a radio frequency test seat is added on a mainboard of a wireless product in a design and development stage, one end of a radio frequency test probe and the radio frequency test seat on the mainboard of the wireless product are buckled in a mechanical structure during testing, the other end of the radio frequency test probe is connected to a test instrument module through a radio frequency test cable, and finally whether board-level radio frequency testing of the wireless product is qualified or not is judged through a measurement result of the test instrument module, and the mainboard of the wireless product is a good product or a defective product is screened to ensure the quality of radio frequency signals. Wireless products represented by mobile phones have been developed to the 5G era, the frequency range of radio frequency signals used on the main board of the wireless products is wider and wider, and in order to ensure the communication quality of the wireless products, more complete board-level radio frequency tests need to be performed before the wireless products are on the market to cover all the frequency ranges of radio frequency signals used after the wireless products are on the market. At present, more radio frequency test seats are added on a mainboard of a wireless product through a design and development stage; the number of the radio frequency test seats on the mainboard of the wireless product in the 2-4G era is calculated by single digit, and the number in the 5G era can be increased to more than 10 to meet the requirement of traditional board-level radio frequency test; for wireless products with more and more complex design, higher performance and better user experience, the design space on the mainboard is very limited, more than 10 radio frequency test seats are only used for meeting the test requirement of guaranteeing the quality of radio frequency signals before the wireless products are sold in the market, and the receiving and transmitting quality of the radio frequency signals on the wireless product board is not improved after the wireless products are sold in the market. On the contrary, more than 10 installation spaces of the board-level radio frequency test seats are reserved in the limited mainboard space in the wireless product design stage, and the material cost of the wireless product is increased. It is therefore desirable to develop a board-level rf signal testing system that does not require an rf test socket to facilitate testing of rf signals and to save costs associated with rf test sockets in upstream designs.

In the process, a radio frequency test seat is directly omitted for testing, and a tuning circuit is required to be designed for impedance matching to ensure that the impedance of a test end is matched with the impedance in the radio frequency circuit, so that the truth and reliability of data can be ensured; because the prior art does not mention how to test the radio frequency signal without a radio frequency test seat, how to adjust and match the impedance during the test is a problem which has great application value and needs to be solved urgently.

SUMMERY OF THE UTILITY MODEL

Aiming at the existing technologies such as: in board-level radio frequency signal testing, there is no radio frequency signal testing tuning circuit for a test system that does not require a radio frequency test socket.

The tuning circuit is used for adjusting matching impedance to match with the impedance of a radio frequency circuit, and comprises a variable capacitance inductance module and a control module; one end of the variable capacitance inductance module is coupled with a test point of a radio frequency circuit to be tested, and the other end of the variable capacitance inductance module is coupled with an external radio frequency signal test instrument; the control module outputs a control signal, and the variable capacitance inductance module adjusts the matching impedance to match the radio frequency circuit impedance in response to the control signal.

Preferably, the radio frequency signal testing device further comprises an echo detection module, wherein one end of the echo detection module is coupled to a connection point of the variable capacitance inductance module and an external radio frequency signal testing instrument, and the other end of the echo detection module is coupled to the control module; the echo detection module is used for detecting echo loss, and the control module responds to the echo loss and outputs the control signal.

Preferably, the variable capacitance and inductance module comprises a plurality of variable capacitances and/or a plurality of variable inductances.

Preferably, the variable capacitance inductance module comprises a first variable capacitor, a first capacitor, a second variable capacitor, a second capacitor, a third variable capacitor and a third capacitor which are sequentially connected in series, wherein a first end of the first variable capacitor is coupled with a test point of a radio frequency circuit to be tested, a first end of the third capacitor is coupled with the third variable capacitor, and a second end of the third capacitor is coupled with an external radio frequency signal test instrument; the circuit also comprises a fourth capacitor, a fourth variable capacitor, a fifth capacitor and a fifth variable capacitor; one end of the fourth capacitor is coupled to a connection point of the first capacitor and the second variable capacitor, the other end of the fourth capacitor is coupled to one end of the fourth variable capacitor, and the other end of the fourth variable capacitor is grounded; one end of the fifth capacitor is coupled to a connection point of the second capacitor and the third variable capacitor, the other end of the fifth capacitor is coupled to one end of the fifth variable capacitor, and the other end of the fifth variable capacitor is grounded; bias voltage adjustment terminals of the first variable capacitor, the second variable capacitor, the third variable capacitor, the fourth variable capacitor, and the fifth variable capacitor are coupled to the control module.

Preferably, the first variable capacitor, the second variable capacitor, the third variable capacitor, the fourth variable capacitor and the fifth variable capacitor are of the type sttic-82G 2.

Preferably, the control module includes a main control unit and a regulation and control unit, the main control unit receives the return loss of the return detection module and receives a regulation and control signal input by a user, the regulation and control unit outputs a variable voltage to the variable capacitance and inductance module in response to the regulation and control signal, and the variable capacitance and inductance module adjusts the matching impedance in response to the variable voltage.

Preferably, the echo detection module comprises a bidirectional coupler, a one-to-two radio frequency switch, a power detector and an analog-to-digital converter which are sequentially connected, one end of the bidirectional coupler is coupled to a connection point of the variable capacitance inductance module and an external radio frequency signal test instrument, and the other end of the bidirectional coupler is connected with the one-to-two radio frequency switch; and the analog-to-digital converter converts the return loss analog signal into a digital signal and transmits the digital signal to the control module.

Preferably, the OUT terminal of the bidirectional coupler is coupled to the variable capacitance inductor module, the IN terminal is coupled to an external radio frequency signal test instrument, the ISO terminal is coupled to the RF1 terminal of the one-to-two radio frequency switch, and the CPL terminal is coupled to the RF2 terminal of the one-to-two radio frequency switch; the RFC end of the one-to-two radio frequency switch is connected with the input end of the power detector, the output end of the power detector is connected with the input end of the analog-to-digital converter, and the output end of the analog-to-digital converter outputs the return loss in a digital signal state to the control module.

A PCB board is also disclosed, which comprises the tuning circuit for testing the radio frequency signal.

A radio frequency signal test device is also disclosed, which comprises the tuning circuit for the radio frequency signal test.

The utility model has the advantages that: the utility model provides a tuning circuit for testing radio frequency signals, which is used for adjusting matching impedance to match with the impedance of a radio frequency circuit and comprises a variable capacitance inductance module and a control module; one end of the variable capacitance inductance module is coupled with a test point of the radio frequency circuit to be tested, and the other end of the variable capacitance inductance module is coupled with an external radio frequency signal test instrument; the control module outputs a control signal, and the variable capacitance inductance module responds to the control signal to adjust the matching impedance to be matched with the impedance of the radio frequency circuit; one end of the variable capacitance inductance module is connected to an antenna spring plate of the radio frequency circuit through a radio frequency test probe, the matching impedance of the variable capacitance inductance module is adjusted through the control module, so that the matching impedance is matched with the impedance of the radio frequency circuit, meanwhile, the return loss can be tested and detected through the return loss detection module, whether the matching impedance is properly matched or not is judged through the return loss until the matching impedance is matched with the impedance in the radio frequency circuit, and the aim of directly testing radio frequency signals through the antenna spring plate is fulfilled; the radio frequency test socket provides a reliable tuning circuit for saving the research of the radio frequency test socket, so that the test result is precise and the data is real.

Drawings

FIG. 1 is a system configuration diagram of the present invention;

fig. 2 is a circuit frame diagram of the present invention;

fig. 3 is a circuit diagram of the variable capacitance inductor module of the present invention;

FIG. 4 is a circuit diagram of the regulating unit of the present invention;

fig. 5 is a return loss detection module circuit of the present invention;

fig. 6 is a structural view of an application example of the present invention.

The main element symbols are as follows:

1. a variable capacitance inductance module; 2. a control module; 21. a main control unit; 22. a regulatory unit; 3. a radio frequency circuit to be tested; 4. a radio frequency signal test instrument; 5. a return loss detection module; 51. a bi-directional coupler; 52. a one-to-two radio frequency switch; 53. a power detector; 54. an analog-to-digital converter;

c17, a first variable capacitor; c18, a first capacitance; c19, a fourth variable capacitor; c20, a second variable capacitor;

c21, a second capacitor; c22, a fifth variable capacitor; c23, a third variable capacitor; c24, a third capacitance; c31, a fourth capacitance; c32, a fifth capacitance.

Detailed Description

In order to make the present invention clearer, the present invention will be further described with reference to the accompanying drawings.

The radio frequency test seat has the function that when the wireless product is used for board-level radio frequency performance test, the radio frequency probe and the radio frequency test seat are mechanically buckled to form electrical connection; when a radio frequency signal is sent or received by a radio frequency chip on a mainboard of the wireless product, the signal is transmitted to a test instrument through a radio frequency test seat and a radio frequency probe to test the radio frequency signal; after the test is finished, pulling out the probe; the signal receiving and transmitting path of the radio frequency chip is changed from the radio frequency chip to the antenna spring plate through the radio frequency test seat, and the antenna spring plate transmits radio frequency signals to achieve the purpose of wireless communication; therefore, the function of the radio frequency test seat is only for testing the test requirement of the radio frequency signal quality in the radio frequency circuit, and does not contribute to improving the radio frequency signal quality; however, with the coming of the 5G era, the design of the main board is more and more complex, the performance requirement is higher and higher, users need to experience better and better wireless products, the design space on the main board is very limited, and the rib design of the radio frequency test seat also becomes an elbow; and the material cost of the wireless product is increased. Moreover, since the design of the radio frequency circuit has been well established, a fixed industrial chain is formed in the production and design of the radio frequency test socket, and in the field of testing of radio frequency signals, technicians generally and directly recognize objective facts that the radio frequency test socket must exist, or the technicians cannot find a more preferable alternative; in order to improve the current design situation of the existing radio frequency circuit, save the design space and the production cost of a radio frequency test seat and ensure the simple and convenient test of radio frequency signals, the inventor designs a board-level radio frequency signal test system without the radio frequency test seat. In order to match such a test system, an important technical premise is to perform impedance matching before testing, but how to tune and judge whether tuned impedance and radio frequency circuit tuning are both problems to be solved.

Specifically, referring to fig. 1-2, the tuning circuit for testing a radio frequency signal is used for adjusting matching impedance to match with impedance of a radio frequency circuit, and includes a variable capacitance inductance module 1 and a control module 2; one end of the variable capacitance inductance module 1 is coupled with a test point of a radio frequency circuit 3 to be tested, and the other end is coupled with an external radio frequency signal test instrument 4; the control module 2 outputs a control signal, and the variable capacitance inductance module 1 responds to the control signal to adjust the matching impedance to be matched with the impedance of the radio frequency circuit; and matching the impedance of the variable capacitance inductance module through the control module.

In this embodiment, the variable capacitance and inductance module includes a plurality of variable capacitances and/or a plurality of variable inductances. It can be known, not limited to the utility model discloses a variable capacitance combination, variable capacitance inductance module can be the circuit that one or more components and parts in variable capacitance, electric capacity, variable inductance, the inductance were combined.

The method specifically comprises the following steps: referring to fig. 3, the variable capacitance inductance module 1 includes a first variable capacitor C17, a first capacitor C18, a second variable capacitor C20, a second capacitor C21, a third variable capacitor C23 and a third capacitor C24 connected in series in sequence, a first end of the first variable capacitor C17 is coupled to a test point of a radio frequency circuit to be tested, in a specific application, a radio frequency test probe may be connected to a first end of the first variable capacitor C17, and referring to fig. 6, the first variable capacitor C17, the first variable capacitor C18, the second variable capacitor C20, the second variable capacitor C21, the third variable capacitor C23 and the third capacitor C24 are; a first end of the third capacitor C24 is coupled to the third variable capacitor C23, and a second end of the third capacitor C24 is coupled to an external rf signal test instrument; further comprising a fourth capacitance C31, a fourth variable capacitor C19, a fifth capacitance C32 and a fifth variable capacitor C22; one end of the fourth capacitor C31 is coupled to the connection point of the first capacitor C18 and the second variable capacitor C20, the other end is coupled to one end of the fourth variable capacitor C19, and the other end of the fourth variable capacitor C19 is grounded; one end of the fifth capacitor C22 is coupled to the connection point of the second capacitor C21 and the third variable capacitor C23, the other end is coupled to one end of the fifth variable capacitor C22, and the other end of the fifth variable capacitor C22 is grounded; bias voltage adjusting terminals of the first variable capacitor C17, the second variable capacitor C20, the third variable capacitor C23, the fourth variable capacitor C24, and the fifth variable capacitor C22 are coupled to the control module. After a variable voltage is output in the control module, the bias voltage adjusting end of the variable capacitor adjusts the matching impedance of the whole variable capacitance inductance module according to the variable voltage; of course, the bias voltage adjusting terminals of the variable capacitors are respectively controlled by the individual control units in the control module. In one particular application, the first, second, third, fourth and fifth variable capacitors are model numbers STPTIC-82G 2.

In this embodiment, please refer to fig. 5, further comprising an echo detection module 5, wherein one end of the echo detection module 5 is coupled to a connection point between the variable capacitance and inductance module 1 and an external rf signal test instrument 4, and the other end is coupled to the control module 2; the return loss detection module 5 is used for detecting return loss, and the control module 2 outputs a control signal in response to the return loss. The echo detection module can obtain the echo loss of the path in the matching impedance state of the current tuning circuit, and judges whether the matching impedance is matched in place to a certain extent through the echo loss; if the return loss is within the preset range, the matching impedance of the variable capacitance inductance unit is matched with the impedance in the radio frequency circuit when the radio frequency circuit of the type is matched, the radio frequency signal can be tested, and meanwhile, after the tuning circuit impedance of a standard board of the type is tuned, the radio frequency circuit of the same type is not required to be tuned again in the follow-up process.

In this embodiment, please refer to fig. 2, the control module 2 includes a main control unit 21 and a regulation and control unit 22, the main control unit 21 receives the return loss of the return detection module, and the main control unit can directly present the return loss on the display to allow the staff of the tuning circuit to judge, the regulation and control signal input by the staff, the regulation and control unit 22 outputs a variable voltage to the variable capacitance and inductance module 1 in response to the regulation and control signal, and the variable capacitance and inductance module 1 adjusts the matching impedance in response to the variable voltage.

In one embodiment, please refer to fig. 4, corresponding to the above 5 variable capacitors, there are 5 regulating units for regulating respectively, where the regulating units include a chip (U5) with model number AD5292BRUZ-50, an SDI pin of the U5 chip is connected to receive a serial signal input, a W pin of the U5 chip is connected to an input end of the U6 chip, an output pin of the U6 chip is connected to a gate of the Q1 triode, a source of the Q1 triode is grounded, a drain of the Q1 triode is connected to a gate of the Q2 triode, a source of the Q2 triode is connected to a bias voltage regulating end of the first variable capacitor, and outputs a variable voltage for regulation; in one embodiment, the transistor Q1 is of type BSS138 and the transistor Q2 is of type SI2307 CDS. Similarly, the other four corresponding regulating units output the variable voltage for regulation in the same manner, and it can be understood that the embodiment is only illustrated by way of example, and is not limited to a component such as a variable capacitor, nor to 5 in number; and the serial model input received by the U5 chip is output through the master control unit. The input end of the main control unit receives and processes the digital signal of the echo detection module.

In the present embodiment, referring to fig. 5, the echo detection module 5 includes a bidirectional coupler 51, a one-to-two radio frequency switch 52, a power detector 53 and an analog-to-digital converter 54, which are connected in sequence, wherein one end of the bidirectional coupler 51 is coupled to a connection point between the variable capacitance inductor module 1 and the external radio frequency signal test instrument 4, and the other end is connected to the one-to-two radio frequency switch 52; the analog-to-digital converter 54 converts the return loss analog signal to a digital signal and transmits it to the control module.

IN a specific embodiment, the OUT terminal of the bidirectional coupler 51 is coupled to the variable capacitance inductor module, the IN terminal is coupled to an external RF signal tester, the ISO terminal is coupled to the RF1 terminal of the one-to-two RF switch, and the CPL terminal is coupled to the RF2 terminal of the one-to-two RF switch; the RFC end of the one-to-two radio frequency switch is connected with the input end of a power detector, the output end of the power detector is connected with the input end of an analog-to-digital converter, and the output end SDO of the analog-to-digital converter outputs return loss in a digital signal state to a control module; that is to say, the output end SDO of the analog-to-digital converter outputs the return loss in the digital signal state to the input end of the main control board, then the output end of the main control board outputs the serial number to the SDI pin of each regulation and control unit, and then the output end of the regulation and control unit outputs a signal with variable voltage to the bias voltage end of the variable capacitor, so as to adjust the matching impedance of the whole variable capacitance inductance unit.

Of course, the circuits for the above unit circuits, such as the variable capacitance inductance module, the control module and the return loss detection module, may be respectively disposed on different PCBs, or may be disposed on the same control board for implementation, and it is easily conceivable that these circuit boards carrying circuits may be directly applied to a radio frequency signal testing device, so as to achieve the purpose of tuning the matching impedance and testing without a radio frequency testing socket.

The utility model has the advantages that:

the matching impedance of the variable capacitance inductance module is adjusted through the control module, so that the matching impedance is matched with the impedance of the radio frequency circuit, meanwhile, the return loss can be tested and detected through the return loss detection module, whether the matching impedance is matched in place or not is judged according to the return loss until the matching impedance is matched with the impedance in the radio frequency circuit, and the purpose of directly testing radio frequency signals through the antenna shrapnel is achieved; the radio frequency test socket provides a reliable tuning circuit for saving the research of the radio frequency test socket, so that the test result is precise and the data is real.

The above disclosure is only for the specific embodiments of the present invention, but the present invention is not limited thereto, and any changes that can be made by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A tuning circuit for testing radio frequency signals is used for adjusting matching impedance to match with the impedance of a radio frequency circuit, and is characterized by comprising a variable capacitance inductance module and a control module; one end of the variable capacitance inductance module is coupled with a test point of a radio frequency circuit to be tested, and the other end of the variable capacitance inductance module is coupled with an external radio frequency signal test instrument; the control module outputs a control signal, and the variable capacitance inductance module adjusts the matching impedance to match the radio frequency circuit impedance in response to the control signal.

2. The tuning circuit for rf signal testing according to claim 1, further comprising an echo detection module, wherein one end of the echo detection module is coupled to a connection point between the varactor module and an external rf signal testing instrument, and the other end of the echo detection module is coupled to the control module; the echo detection module is used for detecting echo loss, and the control module responds to the echo loss and outputs the control signal.

3. The tuning circuit for radio frequency signal testing according to any one of claims 1 or 2, wherein the variable capacitance and inductance module comprises a plurality of variable capacitances and/or a plurality of variable inductances.

4. The tuning circuit for testing radio frequency signals according to claim 3, wherein the variable capacitance inductance module comprises a first variable capacitor, a first capacitor, a second variable capacitor, a second capacitor, a third variable capacitor and a third capacitor connected in series in sequence, a first end of the first variable capacitor is coupled to a test point of a radio frequency circuit to be tested, a first end of the third capacitor is coupled to the third variable capacitor, and a second end of the third capacitor is coupled to an external radio frequency signal test instrument; the circuit also comprises a fourth capacitor, a fourth variable capacitor, a fifth capacitor and a fifth variable capacitor; one end of the fourth capacitor is coupled to a connection point of the first capacitor and the second variable capacitor, the other end of the fourth capacitor is coupled to one end of the fourth variable capacitor, and the other end of the fourth variable capacitor is grounded; one end of the fifth capacitor is coupled to a connection point of the second capacitor and the third variable capacitor, the other end of the fifth capacitor is coupled to one end of the fifth variable capacitor, and the other end of the fifth variable capacitor is grounded; bias voltage adjustment terminals of the first variable capacitor, the second variable capacitor, the third variable capacitor, the fourth variable capacitor, and the fifth variable capacitor are coupled to the control module.

5. The tuning circuit for radio frequency signal testing of claim 4, wherein the first variable capacitor, the second variable capacitor, the third variable capacitor, the fourth variable capacitor and the fifth variable capacitor are of type STPTIC-82G 2.

6. The tuning circuit of claim 2, wherein the control module comprises a main control unit and a control unit, the main control unit receives the return loss of the echo detection module and receives a control signal input by a user, the control unit outputs a variable voltage to the variable capacitance inductor module in response to the control signal, and the variable capacitance inductor adjusts the matching impedance in response to the variable voltage.

7. The tuning circuit for rf signal testing according to claim 2, wherein the echo detection module comprises a bidirectional coupler, a one-to-two rf switch, a power detector and an analog-to-digital converter, which are sequentially connected, one end of the bidirectional coupler is coupled to a connection point between the variable capacitance inductor module and an external rf signal testing instrument, and the other end of the bidirectional coupler is connected to the one-to-two rf switch; and the analog-to-digital converter converts the return loss analog signal into a digital signal and transmits the digital signal to the control module.

8. The tuning circuit for radio frequency signal testing according to claim 7, wherein the OUT terminal of the bidirectional coupler is coupled to the variable capacitance inductor module, the IN terminal is coupled to an external radio frequency signal testing instrument, the ISO terminal is coupled to the RF1 terminal of the one-to-two radio frequency switch, and the CPL terminal is coupled to the RF2 terminal of the one-to-two radio frequency switch; the RFC end of the one-to-two radio frequency switch is connected with the input end of the power detector, the output end of the power detector is connected with the input end of the analog-to-digital converter, and the output end of the analog-to-digital converter outputs the return loss in a digital signal state to the control module.

9. A PCB board comprising a tuning circuit for radio frequency signal testing as claimed in any one of claims 1 to 8.

10. A radio frequency signal testing apparatus, characterized by comprising a tuning circuit for a radio frequency signal test according to any one of claims 1-8.