JPH1073646A - Test method for semiconductor integrated circuit - Google Patents

Abstract

(57) [Summary] To perform a gain tracking test for input signals of different input levels in a short time. In a method of providing an input signal to a semiconductor integrated circuit to be tested, detecting an output signal thereof, and performing a characteristic test of the semiconductor integrated circuit from a relationship between the input signal and the output signal, a frequency close to a measurement frequency is provided. Generating a sine wave signal group having different frequencies and different input levels within the range, providing a signal obtained by combining the sine wave signal groups to the semiconductor integrated circuit as an input signal, and outputting the semiconductor integrated circuit. The method includes a step of developing the signal to the same frequency as the input signal by Fourier transform, and a step of detecting characteristics of the semiconductor integrated circuit for each different input level from the corresponding input signal and output signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test method for a semiconductor integrated circuit, and more particularly to a test method capable of performing a gain tracking test for checking the linearity of input and output of an analog circuit in a short time.

[0002]

2. Description of the Related Art Even in a semiconductor integrated circuit, particularly in the case of an analog circuit such as an operation amplifier or an analog-to-digital converter, a test is performed to determine whether the input and output have linear characteristics. There is a need to do. In addition, with the recent short delivery time and low price of semiconductor integrated circuits, there is a demand for simplification or reduction of the test process.
In the case of an analog circuit, there are more test parameters and the test time tends to be longer than in the case of a digital circuit.

[0003]

In the case of an operation amplifier which is a typical example of an analog circuit,
The gain is generally determined by an external resistance value, and ideally the gain should be constant no matter what frequency or signal amplitude is input. However, if the input amplitude fluctuates due to variations in the circuit elements of the operation amplifier or the like, the gain also fluctuates, resulting in a response characteristic different from the circuit design value. Such a characteristic is called gain tracking property.

Conventionally, an input signal having a plurality of amplitudes is given, the amplitude of each output is determined, and the gain for each input amplitude has been determined. Then, it is checked whether the gain is within a certain allowable range. However, then it is necessary to repeat the measurement for the number of points of the input amplitude,
The test time tends to be longer.

An object of the present invention is to provide a method for testing a semiconductor integrated circuit which solves the above-mentioned problems.

It is another object of the present invention to provide a method for testing a semiconductor integrated circuit, which can perform an input / output characteristic test in a short time.

[0007]

According to the present invention, an input signal is supplied to a semiconductor integrated circuit to be tested, an output signal thereof is detected, and a relationship between the input signal and the output signal is determined. In the method for performing a characteristic test of the semiconductor integrated circuit, a step of generating a sine wave signal group having different frequencies and different input levels within a frequency range close to the measurement frequency, and synthesizing the sine wave signal group Providing a signal as an input signal to the semiconductor integrated circuit; developing an output signal of the semiconductor integrated circuit to the same frequency as the input signal by Fourier transform; and providing the input signal for each input level different from the corresponding input signal and output signal. Detecting a characteristic of the semiconductor integrated circuit.

Further, an additional sine wave signal having a frequency different from the measurement frequency and dispersed in the operating frequency range of the semiconductor integrated circuit is added to the sine wave signal group.

As described above, input signals having different amplitudes are generated with different frequencies, synthesized by an inverse Fourier transform or the like, and an output synthesized wave corresponding to the input synthesized wave is expanded to the same frequency again by the Fourier transform. The relationship between the amplitude input signal and the output signal can be detected simultaneously.

Further, by adding a sine wave having frequencies dispersed within the operating frequency range, frequency characteristics can be obtained at the same time.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention.

FIG. 1 shows an operation amplifier circuit which is an example of an analog circuit. FIG. 2 is a diagram showing the input / output characteristics. In the operation amplifier circuit, resistors R1 and R2 are connected as shown in the differential amplifier circuit 10. Then, an output Xout is generated with respect to the input Xin with a gain proportional to R2 / R1. In that case, an output Xout multiplied by the gain should be generated ideally for an input Xin of any amplitude. However, in practice, when the amplitude of the input increases, the output saturates, and the actual gain decreases.

FIG. 2 shows the saturation characteristic. 1 in the figure
Reference numeral 2 denotes a case of a normal LSI, and within a certain operation range, the input and the output maintain linearity, but the output is saturated as the input amplitude increases. However, the gain is constant while maintaining the linearity within the operating range, and thus, it is determined to be non-defective.

If the characteristics are distorted due to variations in the circuit or the like, the linearity is lost as shown by 14 and 16 in the figure. Therefore, it is necessary to test whether the output maintains linearity with respect to the input within the operating range and the gain becomes constant.

FIG. 3 shows another example of the analog circuit A / A.
It is a D conversion circuit. FIG. 4 is a diagram showing the input / output characteristics. The A / D conversion circuit 20 has an analog input A
For example, a 4-bit digital output Dout is generated for in. The normal input / output characteristics have linearity as shown in FIG. However, the characteristics may be distorted as indicated by 24 and 26 in the figure due to the variation of the internal circuit and the like. Therefore, it is necessary to check the output value when the input amplitude is changed.

FIG. 5 shows a circuit configuration for realizing the test method according to the present invention. In this test circuit, a plurality of input signals having different amplitudes are simultaneously supplied to a semiconductor integrated circuit to be tested, and gains and input / output characteristics at respective amplitudes are obtained from outputs thereof. In such a case, in order to distinguish a plurality of signals, the respective signals are provided with different frequencies.

In FIG. 5, reference numeral 30 denotes a device under test, and 31 denotes an input signal data generator. Input signal data generator 3
In step 1, sine wave data having different amplitudes sequentially at different frequencies is generated in the vicinity of a certain fundamental frequency within the operating characteristic range. This is sine wave data of a plurality of frequencies weighted to the input level. Then, the data is subjected to an inverse Fourier transform to generate synthesized wave data of a function of time.
The synthesized wave data is supplied to the arbitrary waveform generating circuit 32,
An actual analog composite wave 33 is generated. The arbitrary waveform generation circuit 32 is basically a D / A conversion circuit.

The semiconductor integrated circuit 30, which is the circuit under test,
An output wave 34 according to the internal characteristics is output. Then, the digitizer 35 detects a digital value at a certain sampling time interval. This digitizer 35 is basically an A / D conversion circuit.

The digital value of the synthesized wave extracted in this manner is subjected to Fourier transform, expanded to the original sine wave frequency, and returned to the output circuit 36. Therefore, the output amplitude for each frequency is detected, and the relationship with the amplitude of the first input signal is obtained.

For example, in the case of an operation amplifier,
From the amplitude of the input signal and the amplitude of the output signal,
= Xout / Xin, and it is checked whether the gain of the input signal is constant within the operating range of the amplitude. That is, in the example of FIG. 5, the gain is obtained by G = PointN '/ PointN. Here, N 'and N are numbers given corresponding to the input and output signals of each frequency.

As a sine wave spectrum group generated in the input signal data generation unit 31 in FIG. 5, different frequencies near the fundamental frequency in the operating range are used. That is, the frequencies of the input signals point1 to point5 are all within the operating range. Therefore, the output signal has an amplitude that depends on the amplitude characteristic without being affected by the frequency characteristic of the circuit under test 30.

FIG. 6 is a diagram showing an example of a frequency spectrum of a sine wave which is an input signal when the frequency characteristic is detected together with the amplitude characteristic. That is, this is an example of a plurality of input signals when the horizontal axis is frequency and the vertical axis is amplitude. Frequency fa,
fb and fc are the frequencies at both ends and the center in the operating frequency range. Therefore, by giving an input signal having an amplitude of the center A of the operating amplitude range to the frequencies fa, fb, and fc,
Check frequency characteristics without being affected by amplitude.

On the other hand, in order to detect the above-mentioned amplitude dependence, the center frequency fb within the operating frequency range is used as a reference frequency, and f1, f2, f3,
Input signals having different amplitudes such as f4, f5, f6, and f7 are provided. The amplitudes of these sine waves are chosen to be values widely distributed within the operating amplitude range. Therefore, these input signals f1 to f7 can check the amplitude characteristics of the circuit under test without being affected by the frequency characteristics.

Therefore, the sine wave group shown in FIG. 6 is synthesized according to the test circuit shown in FIG. 5 and given to the circuit under test, and the synthesized output is subjected to Fourier transform to develop from the time axis into the frequency domain. Output results of frequency signals can be obtained simultaneously.

Therefore, the frequency characteristics can be checked by using the signals fa, fb, and fc, and the amplitude characteristics can be checked by using the signals f1 to f7.

[0026]

As described above, according to the present invention, when the amplitude of an output signal with respect to an input signal having a plurality of amplitudes, such as a gain tracking test, is determined and the gain and the linearity of input and output are checked, the frequency is determined. By synthesizing sine wave groups having different amplitudes with different amplitudes and simultaneously applying the sine wave groups to the LSI under test and re-expanding the output for each frequency, a test can be performed in a short time. Moreover, the frequency characteristics can be checked at the same time by using the sine waves of the frequencies dispersed in the operating frequency range.

[Brief description of the drawings]

FIG. 1 is an operation amplifier circuit which is an example of an analog circuit.

FIG. 2 is a diagram showing input / output characteristics of an operation amplifier circuit.

FIG. 3 illustrates an A / D conversion circuit that is another example of an analog circuit.

FIG. 4 is a diagram showing input / output characteristics of an A / D conversion circuit.

FIG. 5 is a circuit configuration for realizing a test method according to the present invention.

FIG. 6 is a diagram illustrating an example of a frequency spectrum of a sine wave that is an input signal when detecting a frequency characteristic as well as an amplitude characteristic.

[Explanation of symbols]

 Reference Signs List 30 semiconductor integrated circuit to be tested 31 input signal data generator 32 arbitrary waveform generator 33 digitizer 34 output signal section

Claims (2)

[Claims] An input signal is supplied to a semiconductor integrated circuit to be tested, an output signal is detected, and a characteristic test of the semiconductor integrated circuit is performed based on a relationship between the input signal and the output signal. Generating a sine wave signal group having different frequencies and different input levels within a frequency range close to each other; and providing a signal obtained by synthesizing the sine wave signal group to the semiconductor integrated circuit as an input signal; Developing the output signal of the semiconductor integrated circuit to the same frequency as the input signal by Fourier transform; and detecting the characteristic of the semiconductor integrated circuit for each different input level from the corresponding input signal and output signal. Test method for a semiconductor integrated circuit. 2. The test method for a semiconductor integrated circuit according to claim 1, wherein said sine wave signal group further includes an additional sine wave having a frequency different from said measurement frequency and dispersed in an operating frequency range of said semiconductor integrated circuit. It is characterized by adding a signal.