CN110967590A

CN110967590A - Test method and system for evaluating power tolerance of surface acoustic wave filter

Info

Publication number: CN110967590A
Application number: CN201911415359.4A
Authority: CN
Inventors: 赖定权; 宋崇希; 黄富瑶
Original assignee: Shenzhen Microgate Technology Co ltd
Current assignee: Shenzhen Microgate Technology Co ltd
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-04-07

Abstract

The invention provides a test method and a system for evaluating the power tolerance of a surface acoustic wave filter, which are used for evaluating the power tolerance of the surface acoustic wave filter, judging the reliability of each index of a product in the using process of a client and needing to carry out power related tests on the product. Has the advantages that: 1. the time consumption for testing one device is shorter; 2. the requirement on the long-time working stability of equipment such as a signal generator, a power amplifier and the like is relatively low; 3. within the band pass range, the point of worst power carrying is usually the highest frequency point of the band pass; 4. whether the device can stably work under the power can be judged by observing the fluctuation of the power output value of the device in a specific time.

Description

Test method and system for evaluating power tolerance of surface acoustic wave filter

Technical Field

The invention relates to a test method and a test system for evaluating power tolerance of a surface acoustic wave filter.

Background

With the advent of the 5G era, mobile communication systems have made higher and higher demands on the power tolerance of surface acoustic wave filters. In order to reduce the use risk of the device, prolong the service life of the device and verify whether the device can meet the requirement of the system on the service life of the power, the test of the relevant characteristics of the power is necessary. The surface acoustic wave filter converts an electric signal loaded on an input interdigital transducer into mechanical displacement by utilizing the inverse piezoelectric effect of a piezoelectric material, the mechanical displacement is transmitted on the surface of the piezoelectric material in the form of sound wave, and then the output interdigital transducer converts the acoustic signal into the electric signal by utilizing the piezoelectric effect. Mechanical displacement can generate stress in the metal electrode, and these repeated stresses can cause atomic migration of the metal material, and hillocks and cavities are generated on the surface of the electrode, so that the resistance of the electrode is increased until the electrode is opened or short-circuited, and the performance of the device is deteriorated or completely loses the performance. As the size of the saw filter decreases and the operating frequency increases, the distance between the electrode lines and the fingers becomes smaller and smaller, so that the power-tolerant characteristics of the saw filter are very important.

Generally, the service life of the surface acoustic wave filter is required to be more than 5000h under the action of normal working power. Applying normal working power to the device and then examining the service life and the reliability of each index is obviously unrealistic from the operability. At present, a commonly used method for evaluating the power tolerance of the surface acoustic wave filter is a life test of accelerated aging, and the service life of the surface acoustic wave filter under normal working power is calculated according to a test result and an Eyrings law formula of an Arrhenius model. However, the testing method needs to obtain the corresponding service lives of a plurality of groups of devices under different powers, and has the defects of long time consumption, high requirement on long-time working stability of testing equipment, large error and the like.

Disclosure of Invention

In order to evaluate the power tolerance of the surface acoustic wave filter and judge the reliability of each index of a product in the using process of a client, the power related test needs to be carried out on the product, and the method for testing the limit power which can be born by the product in a specific time is adopted to judge the power tolerance of the product: loading a power value far higher than normal working power, observing whether the device is burnt in a specific time, if the device is not burnt, increasing the input power value in a certain step until the device is burnt in the specific time, thereby obtaining a limit power value which can be borne by the device in the specific time, and further evaluating the power tolerance of the device. The initial power value applied to the device is moderate, the power is too low, and the test consumes long time; the power is too high and the device will burn out immediately.

One of the purposes of the invention is to provide a method for evaluating the power tolerance of the surface acoustic wave filter by testing the limit power on the basis of the traditional accelerated aging life test, and in the test process, the device is placed in a high-temperature incubator at 50 ℃, so that the method has the advantages of short test time, low requirement on equipment, low cost and the like.

The invention also aims to provide a test system for evaluating the power tolerance of a surface wave filter, which comprises a signal generator, a power amplifier, a power detector, a thermostat, an attenuator and a spectrum analyzer; the signal generator is an input power end; the power amplifier is connected with the signal generator and is used for amplifying the output power of a signal source output by the signal generator; the power detector is connected with the power amplifier and is used for detecting the output power of the power amplifier; the power meter calibrates the output power of the power amplifier, and the attenuator is used for attenuating the output power of the device to be tested; the frequency spectrograph is used for detecting whether the device to be detected is damaged; the device to be tested is placed in the constant temperature box, the input end of the device to be tested is connected with the power detector, and the output end of the device to be tested is connected with the attenuator.

Preferably, the input end and the output end of the surface wave filter are respectively connected in series with a first inductor and a second inductor, the input end of the first inductor is grounded through a first capacitor, and the output end of the second inductor is grounded through a second capacitor.

Preferably, the surface acoustic wave filter is connected with a network analyzer in parallel.

The invention evaluates the power tolerance of the device by testing the limit power which can be borne by the surface acoustic wave filter in a specific time, and has the advantages that:

1. the power applied to the device when the limit power is tested is higher than that when the power life test is carried out, so that the performance degradation speed of the device is higher, the time for testing one device is shorter (within tens of minutes), and the time for testing one device in the power life test is relatively longer (several hours or even several days);

2. in the power test process, the power loaded on the device needs to be stable, the time for testing one device is relatively short, and the requirement on the long-time working stability of equipment such as a signal generator, a power amplifier and the like is relatively low;

3. the power loading is point frequency loading, in the test process, the frequency point of the signal generator is set as the highest frequency point of the pass band of the device, and as for the surface acoustic wave filter, the point with the worst power bearing is usually the highest frequency point of the pass band in the pass range;

4. the spectrometer can be used to monitor whether the device performance is degraded or not, and can judge whether the device can stably work under the power by observing the fluctuation of the power output value (for example, whether the fluctuation is larger than 0.1dBm or not) within a specific time.

Drawings

FIG. 1 is a SAW filter and its matching circuit;

FIG. 2 is a schematic diagram of a limiting power test of a surface acoustic wave filter;

fig. 3 is a schematic diagram of a frequency response curve test of the surface acoustic wave filter.

Detailed Description

Referring to fig. 1, fig. 1 shows a saw filter and its matching circuit, when testing, the saw filter and its corresponding matching circuit are all soldered on a test board, so that they have normal frequency response characteristics.

Fig. 2 is a schematic diagram of limiting power test of a surface acoustic wave filter: signal generator input power; the power amplifier is responsible for amplifying the output power of the signal source; the power meter is responsible for calibrating the output power of the power amplifier; a high-temperature thermostat creates a high-temperature environment, and a power detector is arranged; the attenuator is used for attenuating the output power of the device; the spectrometer is used for monitoring the deterioration of the performance of the device; the network analyzer is used for testing the frequency response characteristics of the device before and after burning.

FIG. 3 is a schematic diagram of a frequency response curve test of a surface acoustic wave filter, wherein devices need to be taken out after each power value is loaded for a specific time, a network analyzer is used for testing the frequency response characteristics of the devices, the curve is normal, the devices are connected to a limit power test system again, and higher power is loaded; the device burns out if the curve changes significantly.

The test in the invention takes the irrecoverable damage of the device under the action of the power signal as the failure sign of the device. The basis for judging the failure of the device is as follows: (1) the power value displayed by the frequency spectrograph is obviously reduced; (2) the frequency characteristic curve of a network analyzer testing device is obviously changed; (3) and dissecting the burnt device, and confirming the burnt position of the internal chip.

Claims

1. A test method for evaluating the power tolerance of a surface acoustic wave filter is characterized in that the test method is to place a device to be tested in a thermostat with the temperature of 50 ℃ for power tolerance test.

2. A test system for evaluating the power tolerance of a surface wave filter is characterized by comprising a signal generator, a power amplifier, a power detector, an incubator, an attenuator and a spectrum analyzer; the signal generator is an input power end; the power amplifier is connected with the signal generator and is used for amplifying the output power of a signal source output by the signal generator; the power detector is connected with the power amplifier and is used for detecting the output power of the power amplifier; the power meter calibrates the output power of the power amplifier, and the attenuator is used for attenuating the output power of the device to be tested; the frequency spectrograph is used for detecting whether the device to be detected is damaged; the device to be tested is placed in the constant temperature box, the input end of the device to be tested is connected with the power detector, and the output end of the device to be tested is connected with the attenuator.

3. The test system for evaluating power tolerance of a surface acoustic wave filter as claimed in claim 2, wherein an input terminal and an output terminal of said surface acoustic wave filter are connected in series with a first inductor and a second inductor, respectively, an input terminal of said first inductor being grounded via a first capacitor, and an output terminal of said second inductor being grounded via a second capacitor.

4. The test system for evaluating power tolerance of a surface acoustic wave filter as set forth in claim 2, wherein said surface acoustic wave filter is connected in parallel with a network analyzer.