JPH0850161A - Measuring method of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a measuring method of cut-off frequency in which the number of measuring points can be reduced while keeping the measuring precision, and the measuring time can be shortened. CONSTITUTION:Respective gains yL, yH in two minimum and maximum frequencies xL, xH of a measuring frequency range for conforming a gain to a prescribed value yADJ are measured. The approximate value x'ADJ of frequency for conforming the gain to the prescribed value yADJ is arithmetically determined by linear approximation. When the approximate value x'ADJ of frequency determined by linear approximation is largely different from xADJ which is the actual frequency value, the frequency characteristic is assumed to be a broken line to approximate it. Namely, optional frequencies x1, x2 are taken between xL and xH, and gains yL, y1, y2, yH in the respective frequencies yADJ measured It is then confirmed between which gains yADJ is situated. In this case, since yADJ is between yL and y1, the approximate value x'ADJ in yADJ is arithmetically determined by linear approximation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a semiconductor device having frequency characteristics and non-linear characteristics.

[0002]

2. Description of the Related Art When measuring a cutoff frequency, which is a frequency characteristic of an output signal of a semiconductor device, it is necessary to find a frequency corresponding to a -3 dB point which is a break point.

As a conventional method, as shown in FIG.
First, the frequency measurement range is equally divided into n (in FIG. 3, n =
Then, the gain for each frequency is measured, and the frequencies x ₄ and x ₅ giving the gains y ₄ and y ₅ including the predetermined value y ₀ are obtained. As a result, the frequency that gives a predetermined gain can be obtained with a resolution of 1 / n (n = 10 in FIG. 3) of the frequency measurement range.

Further, by dividing the frequency x ₄ and the frequency x ₅ into n and performing the same operation as described above, it is possible to obtain a frequency giving a predetermined gain with a resolution of 1 / n ² of the frequency measurement range. .

In this way, when the same operation is repeated m times, the resolution becomes 1 / n ^m of the frequency measurement range. The values of n and m may be selected according to the required measurement accuracy. Usually, for n = 10, a value of m of 2-3 is sufficient.

[0006]

However, in the above-mentioned conventional method, when the gain is made to coincide with the predetermined value y ₀ , the time required for the gain can be expressed by the number of measurement points × one measurement time. Since the score is 20 to 30, there is a problem that it takes time to complete the measurement.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a semiconductor device measuring method which can reduce the number of measuring points and shorten the measuring time while maintaining the measuring accuracy.

[0008]

In order to achieve the above object, the present invention provides a broken line approximation of the relationship between the output signal frequency and the gain in the measurement of the cutoff frequency which is the frequency characteristic of the output signal of the semiconductor device. , The cutoff frequency is approximately calculated by calculation.

[0009]

According to the structure of the present invention, the relationship between the frequency of the output signal and the gain is approximated by a polygonal line, so that the accuracy of the measurement by the approximation can be improved and the number of measurement points can be greatly reduced. Is possible.

[0010]

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

FIG. 1 is a test circuit diagram of a semiconductor device according to the present invention. In FIG. 1, a signal generator 1 is connected to an input terminal 4 of a semiconductor device 2, and a semiconductor device 2
Generate the input signal of. The AC level meter 3 is connected to the output terminal 5 of the semiconductor device 2 and
Measure the output signal of.

FIG. 2 is a diagram showing the frequency characteristic measured in the circuit shown in FIG. 1 and showing the relationship between the frequency and the gain.

[0013] As shown in FIG. 2 (a), each of the gain y _L and the first minimum and maximum two-point measurement frequency range to match the gain to a predetermined value y _ADJ frequency x _L and x _H Measure y _H. Assuming that the relationship between the frequency x and the gain y is a straight line (linear function) using this measured value, the gain x is y = y _H + (x−x _H ) (y _H −y _L ) / (x _H − x _L ) ... (1), and the approximate value x ′ _ADJ of the frequency at y _ADJ is x ′ _ADJ = x _H + (y _ADJ −y _H ) (x _H −x _L ) / (y _H − y _L ) ... Represented by (2). As a result, the approximate value x ′ _ADJ of the frequency for matching the gain with the predetermined value y _ADJ can be obtained by calculation from the linear approximation. However, as shown in FIG. 2A, the approximate value x ′ of the frequency obtained by the linear approximation
_{If ADJ} is significantly different from the actual frequency value, x _ADJ , this approximation will lack accuracy.

2 (b) will be described. Figure 2
(B) the frequency x _L, x _H takes an arbitrary frequency x _1, x ₂ between the respective frequencies x _L, x _1, x _2, x _H gain y _L,
Measure y ₁ , y ₂ , y _H. Next, check which gain y _ADJ exists between. In the case of FIG. 2B, since y _ADJ exists between y _L and y ₁ , it is possible to assume that the relationship between the frequency x and the gain y at the frequencies x _L and x ₁ is a straight line. , Y _ADJ , the approximate value x ′ _ADJ of the frequency at the time of _ADJ can be calculated.

That is, by approximating the frequency characteristic assuming that it is a broken line, it is possible to obtain a more accurate measured value than in the case of linear approximation.

Although FIG. 2B shows the case where the frequency is divided into three, if the number of divisions is further increased, the accuracy of the polygonal line approximation will be improved.

In the embodiment, the method of measuring the cutoff frequency, which is the frequency characteristic, by the polygonal line approximation has been described, but the similar polygonal line approximation can be used for the non-linear characteristic other than the frequency measurement.

[0018]

According to the semiconductor device measuring method of the present invention, the accuracy of measurement by approximation can be improved and the number of measurement points can be greatly reduced, so that the measurement time can be greatly shortened.

[Brief description of drawings]

FIG. 1 is a test circuit diagram of a semiconductor device according to an embodiment of the present invention.

2A and 2B are diagrams showing frequency characteristics measured in the circuit shown in FIG.

FIG. 3 is a diagram for explaining a conventional measuring method.

[Explanation of symbols]

 1 signal generator 2 semiconductor device 3 AC level meter

Claims (1)

[Claims] 1. A method for measuring a frequency characteristic of an output signal of a semiconductor device, wherein the cutoff frequency is calculated by performing a linear approximation of a gain at intervals of a predetermined frequency of the output signal and calculating the cutoff frequency. Measuring method.