JPS614977A - Characteristic measuring device for semiconductor element - Google Patents

Abstract

PURPOSE:To detect accurately a gain variation point in a linear operation range by adding a low-frequency, low-level signal to a high-frequency signal supplied to a semiconductor element to be measured, and measuring the variation of an output signal caused by the variation of an input signal to the semiconductor element to be measured. CONSTITUTION:The measuring device consists of a signal generator 1, directional coupler 2, semiconductor element 3 to be measured, wattmeters 4 and 5, and control part 6. Amplitude modulation is imposed upon the output signal of the signal generator 1 and the modulated signal is applied to the semiconductor element 3 to be measured through the directional coupler 2. Then, the applied electric power and the output electric power of the semiconductor element 3 to be measured are measured by the wattmeters 4 and 5, whose measured values are inputted to the control part 6. Further, the control part 6 measures the difference between the measured values to calculate the gain variation point in the linear operation range accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor device characteristic device, and more particularly to a power gain measuring device thereof.

(Prior art) For example, in the relationship between the applied power of a transistor and its output power, there is a linear amplification region where the output power increases with a constant amplification factor as the applied power increases, and a linear amplification region where the output power increases with a constant amplification factor as the applied power increases. Therefore, there is a non-linear amplification region where the amplification factor of the output power gradually decreases and increases.

For example, in the linear amplification region shown above, if a multi-stage amplifier is configured using transistors that do not exhibit a constant gain, it will cause a significant loss of amplifier performance, so it is necessary to accurately measure slight changes in transistor gain in the linear region. A device is required to do this.

The conventional method for measuring gain changes in the linear region is to use a signal generator with stable output signal level and frequency, lower the long signal to a level at which the transistor sufficiently operates in the linear amplification region, and then gradually increase the large sword signal. Generally, a method is considered in which the measurement is continued until the nonlinear amplification region is reached, and the change in gain, that is, the change in slope, in the linear region is measured.

FIG. 3 shows a system block diagram of a conventional transistor output signal characteristic measuring device, in which an input signal is applied from a signal generator 1 to a transistor to be measured 3 via a directional coupler 2, and a power meter The input signal level is measured at 4, and the output power from the transistor to be measured 3 is measured at wattmeter 5.

(Problem to be solved by the invention) In this case, when determining the gain change in the linear operating region, it cannot be determined directly, so repeated measurements are required to accurately determine the linear gain and detect slight gain changes. In addition, it requires a long measurement time, such as converting the power gain for each measurement, and has the disadvantage that it does not have the measurement accuracy to detect slight changes in gain.

An object of the present invention is to provide a measuring device that makes it possible to accurately determine a gain change point in a linear operating region.

(Means for solving the problem) According to the present invention, the power applied to the semiconductor device under test is detected using a signal obtained by adding a low frequency, low signal level signal to the high frequency signal applied to the semiconductor device under test. a first detection section that detects the output power from the semiconductor device under test;
a detection unit, and a control unit that performs predetermined processing based on the detection values of the first and second detection units;
and a signal level difference from the second detection section to obtain a semiconductor device characteristic measuring device that detects a defective portion in a constant power gain region in the amplification characteristic of the semiconductor device under test.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a characteristic measuring device according to an embodiment of the present invention, in which an output signal from a signal generator 1 is amplitude-modulated and applied to a transistor under test 3 via a directional coupler 2. . The power applied to the transistor under test 3 is determined by the wattmeter 4.
The output power of the transistor to be measured 3 is accurately measured by the wattmeter 5. The measured values of the wattmeter 4 and the wattmeter 5 are input to the control unit 6, and the difference between them is measured.

In this measurement device, in order to find the non-linear part of the linear amplification region of the input/output power characteristics of the transistor under test, a low frequency/low level signal is added to a specified high frequency signal. Measure changes in the output signal. In other words, as the gain increases or decreases, the output signal clearly shows increases and decreases. The explanation will be continued below by showing the input/output power characteristics of the transistor in FIG.

The input/output power characteristics of a normal transistor are characteristic 10.
However, in a transistor having a gain change in its input/output characteristics, a change in gain occurs in the linear amplification region as shown in characteristic 11. Regarding the output signal of the control unit 6 and each characteristic diagram, for a normal transistor, the output signal of the control unit 6 is a straight line with zero slope in the linear amplification region, and in the non-linear amplification region (saturated As the power gain gradually decreases within the region), the output signal level also decreases (characteristic 12).

However, when a gain change occurs, the output signal from the control unit 6 of a transistor that does not have a constant power gain in the linear increasing region is above or below the straight line with zero slope in the constant power gain region. This results in a signal with changes as shown in characteristic diagram 13.

(Effect of the invention) In this way, when the output signal shows a slight but steep change in response to a constant change in the input signal of the transistor,
In conventional measurements, it was difficult to detect the gain changing part, but 1
By using this measuring device, it is possible to clearly detect the presence of the gain changing section. In addition, when measuring power transistors, the measurement time is long, which causes large thermal fluctuations in the transistor, and when measuring minute changes in signals and reproducibility, there is a lack of accuracy. Is it necessary to measure the reduction in measurement time? From this point of view as well, this measuring device is extremely effective in reducing the working time and measuring accurate characteristics of transistors.

[Brief explanation of the drawing]

FIG. 1 is a system block diagram of an input/output characteristic measuring device according to an embodiment of the present invention, and FIG. 2(a) is a block diagram of the system. (b) is an input/output power characteristic diagram and an input/gain characteristic diagram according to the present embodiment. FIG. 3 is a system block diagram of a conventional input/output characteristic measuring device. 1... Signal generator, 2... Directional coupler, 3... Semiconductor element under test, 4, 5...
...Power meter, 6...Control unit, 10...
Input/output power characteristic diagram of a normal transistor, 11...
...Input/output power characteristic diagram of a transistor with gain change in the linear amplification region, 12...Characteristic diagram 10
13... Output signal of the control unit 6 for the characteristic diagram ti. Rod / Circle Potato 2 Diagram

Claims (1)

[Claims] a first detection unit that detects power applied to the semiconductor device under test using a signal obtained by adding a low frequency, low signal level signal to a high frequency signal applied to the semiconductor device under test; and an output from the semiconductor device under test. a second detection unit that detects electric power;
a control section that performs a predetermined process based on the detection values of the first and second detection sections, in the control section, a signal level difference from the first and second detection sections is determined, A characteristic measuring device for a semiconductor device, characterized in that it detects a defective part in a constant power gain region in the amplification characteristic of the semiconductor device to be measured.