Waveform generator, waveform shaper, and testing apparatus

• US 20070038405A1
• Filed: 05/30/2006
• Published: 02/15/2007
• Est. Priority Date: 06/01/2005
• Status: Active Grant

• Current Assignee: Advantest Corporation
• Original Assignee: Advantest Corporation
• Inventors: Kawabata, Masayuki
• Granted Patent: US 7,342,524 B2
• Time in Patent Office: Days
• US Class Current: 702/124
• CPC Class Codes: H03K 4/08 having sawtooth shape

Abstract

There is provided a waveform generator that generates a waveform. The waveform generator includes: a lamp waveform generating section that generates a lamp wave of which a signal value linearly changes for a predetermined period; a square wave generating section that generates a square wave of which pulse width is generally equivalent to the predetermined period; a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave and the square wave; and a low-pass filter that removes a predetermined frequency band component from a waveform output from the waveform adding section.

Claims

1. A waveform generator that generates a waveform, comprising:

a lamp waveform generating section that generates a lamp wave of which a signal value linearly changes for a predetermined period;

a square wave generating section that generates a square wave of which pulse width is generally equivalent to the predetermined period;

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave and the square wave; and

a low-pass filter that removes a predetermined frequency band component from a waveform output from said waveform adding section.

3. The waveform generator as claimed in claim 1, wherein said square wave generating section generates the square wave that has amplitude according to an inclination of a waveform of the lamp wave for the predetermined period and a time constant of said low-pass filters.

4. The waveform generator as claimed in claim 3, wherein said square wave generating section generates the square wave that has amplitude according to a value made by multiplying an inclination of the waveform by the time constant.

5. The waveform generator as claimed in claim 3, wherein

the waveform generator further comprises an inclination detecting section that detects an inclination of a waveform of the lamp wave, and

said square wave generating section generates the square wave based on an inclination of the waveform detected from said inclination detecting section.

2. A waveform generator that generates a waveform, comprising:

a lamp waveform generating section that generates a lamp wave of which a signal value linearly changes for a predetermined period;

a square wave generating section that generates a square wave of which pulse width is generally equivalent to the predetermined period;

a first low-pass filter that removes a predetermined frequency band component from the lamp wave;

a second low-pass filter that has the generally same characteristic as that of said first low-pass filter and removes the frequency band component from the square wave; and

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave output from said first low-pass filter and the square wave output from said second low-pass filter.

10. The waveform generator as claimed in claim 2, wherein said square wave generating section generates the square wave that has amplitude according to an inclination of a waveform of the lamp wave for the predetermined period and a time constant of said low-pass filters.

11. The waveform generator as claimed in claim 10, wherein said square wave generating section generates the square wave that has amplitude according to a value made by multiplying an inclination of the waveform by the time constant.

12. The waveform generator as claimed in claim 10, wherein

the waveform generator further comprises an inclination detecting section that detects an inclination of a waveform of the lamp wave, and

said square wave generating section generates the square wave based on an inclination of the waveform detected from said inclination detecting section.

6. A waveform shaper that removes noises from an input lamp wave, comprising:

an inclination detecting section that detects an inclination of a waveform of the lamp wave;

a period detecting section that detects a period for which a signal value in the lamp wave linearly changes;

a square wave generating section that generates a square wave according to an inclination of the waveform detected from said inclination detecting section and the period detected from said period detecting section;

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave and the square wave; and

a low-pass filter that removes a predetermined frequency band component from a waveform output from said waveform adding section.

7. A waveform shape that removes noises from an input lamp wave, comprising:

an inclination detecting section that detects an inclination of a waveform of the lamp wave;

a period detecting section that detects a period for which a signal value in the lamp wave linearly changes;

a square wave generating section that generates a square wave according to an inclination of the waveform detected from said inclination detecting section and the period detected from said period detecting section;

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave and the square wave; and

a first low-pass filter that removes a predetermined frequency band component from the lamp wave;

a second low-pass filter that has the generally same characteristic as that of said first low-pass filter and removes the frequency band component from the square wave; and

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave output from said first low-pass filter and the square wave output from said second low-pass filter.

8. A testing apparatus that tests an AD converter, comprising:

a waveform generator that generates a lamp wave to be input into the AD converter; and

a decider that decides the good or bad of the AD converter based on a digital signal output from the AD converter according to the lamp wave, wherein

said waveform generator comprises;

a lamp waveform generating section that generates a lamp wave of which a signal value linearly changes for a predetermined period;

a square wave generating section that generates a square wave of which pulse width is generally equivalent to the predetermined period;

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave and the square wave; and

a low-pass filter that removes a predetermined frequency band component from a waveform output from said waveform adding section.

9. A testing apparatus that tests an AD converter, comprising:

a waveform generator that generates a lamp wave to be input into the AD converter; and

a decider that decides the good or bad of the AD converter based on a digital signal output from the AD converter according to the lamp wave, wherein

said waveform generator comprises;

a lamp waveform generating section that generates a lamp wave of which a signal value linearly changes for a predetermined period;

a square wave generating section that generates a square wave of which pulse width is generally equivalent to the predetermined period;

a first low-pass filter that removes a predetermined frequency band component from the lamp wave;

a second low-pass filter that has the generally same characteristic as that of said first low-pass filter and removes the frequency band component from the square wave; and

a waveform adding section that generally accords a timing at which a signal value in the lamp wave begins to be changed and a timing at a leading edge of the square wave, to add the lamp wave output from said first low-pass filter and the square wave output from said second low-pass filter.