JP3166147B2 - Test signal generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test signal generator used for an IC tester for performing a test by applying various test signals to a device under test (IC, LSI, etc.).
The present invention relates to a test signal generator that can output various test signals, has a short set time, and has a small memory capacity.

[0002]

2. Description of the Related Art For example, in a conventional IC tester, when testing an FM demodulator or an AM demodulator, a signal output from a sine wave generator is FM-modulated or AM-modulated by a modulator. And AM demodulators as test signals. However, when testing an FM demodulator or an AM demodulator, such a test signal obtained by modulating a sine wave is not sufficient, and a signal obtained by modulating a two-tone signal obtained by combining two frequency signals or a signal obtained by modulating a triangular wave is used. Are also required as test signals. Further, in order to test a TV audio receiver, an FM stereo receiver, and the like, a TV audio multiplexed signal and an FM stereo signal are required, but the above configuration could not be output. Therefore, when such a test signal is generated, the test signal is stored in a memory, data is read from the memory, D / A converted, and an FM demodulator, an AM demodulator, a TV audio receiver, and an FM stereo are output. Testing of receivers, etc. was being conducted.

[0003]

In such a configuration,
A test of a demodulator requires a large memory capacity because a test signal component includes a high-frequency carrier. This generally increases the cost of the device because the memory is expensive. In addition, a large amount of time is required for setting a modulation operation and a test signal in a memory.

[0004] Since a TV audio multiplexed signal and an FM stereo signal are multiplexed signals, they require a memory capacity of the least common multiple of the frequency of the signal to be synthesized. Therefore, as the number of signals increases, the memory capacity also increases. Further, a modulation operation of the modulation component of the multiplex signal, that is, a long setting time is required. SUMMARY OF THE INVENTION It is an object of the present invention to provide a test signal generator that can generate various test signals, has a short set time, and has a small memory capacity.

[0005]

SUMMARY OF THE INVENTION The present invention provides a memory for storing an arbitrary waveform, a sine wave generator for generating a sine wave signal which is the basis of a test signal, and an arbitrary waveform and sine wave generator from the memory. The first is to select and output the sine wave signal from
A switching section comprising a second selector, and a second
Input the output from the selector and use this signal as the modulation signal.
Includes a modulator for modulating, by adding the output from the first selector or <br/> these output and the modulator of the switching unit, an adder for outputting a test signal, the Te, the Arbitrary waves in memory
The shape is set, and the arbitrary wave is set by the first and second selectors.
Select the shape and sine wave signal, and use various multiplex signals as test signals
Can be output .

[0006]

According to the present invention, the sine wave which is the basis of the test signal is generated by the sine wave generator. A complicated signal (arbitrary waveform) is generated by being stored in a memory. The switching unit switches these outputs and supplies them to the modulator or the adder. Then, the adder adds the output from the switching unit and the output from the modulator, and outputs the result as a test signal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention. In the figure, reference numeral 1 denotes a memory for storing an arbitrary waveform. Reference numeral 2 denotes a sine wave generator (for example, a direct digital synthesizer) which generates a sine wave signal. Reference numeral 3 denotes a switching unit which receives an output from the memory 1 and a sine wave signal from the sine wave generator 2 and switches under the control of a control unit (not shown).
The switching unit 3 includes selectors 31 and 32,
A memory 1, a sine wave generator 2, and no input are selected and output, respectively. Reference numeral 4 denotes a modulator to which an output from the switching unit 3 (selector 32) is input, and performs modulation such as FM modulation and AM modulation. An adder 5 adds the output from the switching unit 3 (selector 31) and the output from the modulator 4 and outputs the result as a test signal.

[0008] The operation of such an apparatus will be described below for the case of testing an FM demodulator and the case of testing a TV audio receiver. When testing an FM demodulator. Here, as a test signal, a signal obtained by modulating a sine wave,
An example of outputting a two-tone signal and a modulated signal will be described. The memory 1 stores a two-tone signal as an arbitrary waveform.

First, an example of outputting a signal obtained by modulating a sine wave will be described. The control unit causes the selector 31 to select no signal and causes the selector 32 to select the sine wave generator 2. As a result, the data in the memory 1 is not used. The modulator 4 inputs the sine wave signal output from the sine wave generator 2 via the selector 32 and performs FM modulation. Then, the adder 5 adds the no-signal from the selector 31 and the signal from the modulator 4 and outputs the result as a test signal. The test signal is D / A-converted and applied to an FM demodulator (under test), and the IC tester performs a test.

When outputting a signal obtained by modulating a two-tone signal, the control unit causes the selector 31 to select no signal and the selector 32 to select the memory 1. Thus, the sine wave generator 2 is not used. The modulator 4 inputs the data from the memory 1 via the selector 32 and
Perform modulation. Then, the adder 5 adds the no-signal from the selector 31 and the signal from the modulator 4 and outputs the result as a test signal. The test signal is D / A-converted and applied to an FM demodulator (under test), and the IC tester performs a test.

When testing a TV audio receiver. FIG. 2 is a diagram showing a frequency spectrum of a TV audio multiplex signal. Here, the memory 1 stores a combined signal of the L + R signal and the pilot signal. The control unit causes the selector 31 to select the memory 1 and causes the selector 32 to select the sine wave generator 2. Here, the sine wave output from the sine wave generator 2 is an LR signal. The modulator 4 inputs the sine wave signal output from the sine wave generator 2 via the selector 32 and performs FM modulation. The adder 5 is connected to the selector 3
1 from the memory 1 and a signal from the modulator 4 are added and output as a test signal. This test signal is D / A-converted and supplied to a TV audio receiver (under test), and the IC tester performs a test.

As described above, the sine wave which is the basis of the test signal is generated by the sine wave generator 2, the complicated signal is stored in the memory 1, these are switched by the switching unit 3, and the modulation is performed by the modulator 4. Since the addition is performed by the adder 5, various test signals can be generated, and the memory capacity can be reduced.

Further, since the modulation is performed by the modulator 4, no modulation operation is required, so that the set time can be shortened. In the test of the demodulator, since the modulation is performed by the modulator 4, it is not necessary to store the carrier component in the memory 1, so that the time for storing data in the memory 1, that is, the set time can be shortened. .

The present invention is not limited to this, and in the embodiment, an example has been described in which the present invention is constituted by a digital circuit. However, the present invention may be constituted by an analog circuit. In that case,
A D / A converter is required after the memory 1. Also, the configuration in which the switching unit 3 selects no signal has been described.
May be configured so that only the memory 1 and the sine wave generator 2 are switched, the switch means is provided in the signal path, and the signal is not transmitted to the subsequent stage. The switching unit 3 is controlled by the control unit, but may be manually switched.

[0015]

According to the present invention, the following effects can be obtained. The basic sine wave of the test signal is generated by a sine wave generator, complex signals are stored in a memory, these are switched by a switching unit, modulated by a modulator, and added by an adder. Therefore, various test signals can be generated and the memory capacity can be reduced.

Further, since the modulation is performed by the modulator, no modulation operation is required, so that the set time can be shortened. In the test of the demodulator, since the modulation is performed by the modulator, it is not necessary to store the carrier component in the memory. Therefore, the time for storing the data in the memory, that is, the set time can be shortened.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a frequency spectrum of a TV audio multiplex signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Memory 2 Sine wave generator 3 Switching part 4 Modulator 5 Adder

Continuation of front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/3183 G01R 31/00 H04H 5/00 302 H04N 17/00

Claims (1)

(57) [Claims] 1. A memory for storing an arbitrary waveform, a sine wave generator for generating a sine wave signal as a basis of a test signal, and an arbitrary waveform from the memory and a sine wave signal from the sine wave generator are selected. first, to output the <br/> switching unit comprising a second selector receives an output from the second selector of the switching unit, this
Includes a modulator for modulating the signal as a modulation signal, adds the output from the output to the modulator from the first selector of the switching unit, an adder for outputting a test signal, wherein the memory And the first and second waveforms
2 Select an arbitrary waveform and a sine wave signal by the selector
A test signal generator capable of outputting various multiplexed signals as test signals.