Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2002-01-02
2004-06-29
Han, Jessica (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C323S232000, C323S352000
Reexamination Certificate
active
06756774
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constant voltage source, a constant voltage source circuit board and a method for supplying a constant voltage. The present invention also relates to a Japanese Patent Application No. 2000-3970 filed at Jan. 12, 2000, which is incorporated herein by reference.
2. Description of the Related Art
There is a conventional method for testing a semiconductor integrated circuit device using a semiconductor testing apparatus, where a constant voltage is supplied to the semiconductor integrated circuit device and a constant-current is measured. The semiconductor testing apparatus includes a constant voltage source for applying a constant voltage to a load. However, when the load enters into an operating state from a stand-by state, a current flows out of the constant voltage source and the voltage in the constant voltage source near the semiconductor device drops.
In general, a conventional constant voltage source has an operational amplifier and a feedback circuit The feedback circuit provides output voltage feedback to the operational amplifier, so that voltage variation is suppressed. However, as the operating speed of the semiconductor integrated circuit increases, testing on a high frequency range is required. Therefore, the output voltage feedback by the feedback circuit cannot follow the voltage variation.
Another conventional constant voltage source includes a bypass capacitor near the load in order to suppress voltage drop in the constant voltage source near the load. Since the bypass capacitor is located near the load, it is possible to correct the output voltage quicker than the feedback circuit. Therefore, it is possible to perform testing on a high frequency range, which is required as the operating speed of the semiconductor integrated circuit increases.
However, since the bypass capacitor is located near the load, the area of the bypass capacitor should be small. Therefore, it is impossible to make the capacitance of the bypass capacitor be enough to fully correct the output voltage variations. Further, in general, the bypass capacitor is coupled to the load in parallel. Therefore, a resistor and the constant voltage source in the constant voltage source form a CR circuit. The frequency characteristics of the CR circuit and the operational amplifier make the operation of the constant voltage source on a high frequency range unstable. If the capacitance of the bypass capacitor is increased, the operation of the constant voltage source becomes unstable even on a low frequency range.
Recently, operating speed of the semiconductor device has become increasingly faster. Therefore, it is required that the semiconductor testing apparatus perform a stable operation on a high frequency range by considering line resistances etc. as the operating speed increases. Further, it is also desirable to increase operating speed of the testing apparatus in order to increase throughput.
Therefore, it is required that the constant voltage source supply a predetermined level of output voltage to the load independently of the variation of currents supplied to the load.
Further, it is also required that the constant voltage source fully correct the output voltage supplied to the load before output voltage feedback of the feedback circuit follows the output voltage variation if the output voltage variation is dependent on the variation of currents flowing to the load.
Further, it is also required that the constant voltage source supply stable output voltage to the load during the operation on a high frequency range as the operating speed of a semiconductor integrated circuit device increases.
Further, it is also required that the semiconductor testing apparatus perform a stable testing on a high frequency range by considering line resistances etc. as the operating speed of a semiconductor integrated circuit device increases, and that the operating speed of the testing apparatus be increased in order to increase throughput.
Therefore, it is the object of the present invention to provide a constant voltage source, a constant voltage source circuit board and a method for supplying a constant voltage, which can meet the above and other requirements. The above object of the present invention can be achieved by combinations of features of independent claims. Dependent claims provide other preferred features of the present invention.
Therefore, it is an object of the present invention to provide a constant voltage Source, a constant voltage source circuit board and a method for applying a constant voltage which is capable of overcoming the above drawbacks accompanying the conventional art. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
SUMMARY OF THE INVENTION
According to the first aspect of the present invention, a constant voltage source circuit comprising: a constant voltage supplying circuit comprising an operational amplifier for supplying an output voltage to a load and a feedback circuit for feeding back the output voltage to the operational amplifier; a first inductance unit disposed between the constant voltage supplying circuit and the load; and a first bypass capacitor of which one terminal is coupled between the first inductance unit and the load and the other terminal is coupled to a constant voltage unit.
Inductance between the first bypass capacitor and the load of the constant voltage source circuit may be smaller than inductance between the constant voltage supplying circuit and the load.
The constant voltage source circuit may further comprise a first resistor coupled to the first inductance unit in parallel.
The constant voltage source circuit may further comprise a compensation circuit comprising a second resistor, a second inductance unit and a second bypass capacitor, one end of each of the second resistor, the second inductance unit and the second bypass capacitor being coupled to each other, wherein the other end of the second resistor is coupled to an end of the first inductance unit near the constant voltage supplying circuit, the other end of the second inductance unit is coupled to a load side end of the first inductance unit and the other end of the second bypass capacitor is coupled to the constant voltage unit.
Inductance between the second bypass capacitor and the load of the constant voltage source circuit maybe larger than inductance between the first bypass capacitor and the load.
Capacitance of the second bypass capacitor of the constant voltage source circuit may be larger than capacitance of the first bypass capacitor.
Inductance of the second inductance unit of the constant voltage source circuit maybe smaller than inductance of the first inductance unit.
At least one of inductances between respective the first and second bypass capacitors and the load of the constant voltage source circuit maybe inductance of respective wiring lines between the first and second bypass capacitors and the load.
At least one of the first and second inductance units of the constant voltage source circuit may be a wiring line.
Inductances between respective the first and second bypass capacitors and the load of the constant voltage source circuit may be inductances of wiring lines between the first or second bypass capacitors and the load, and the first and second inductance units may be wiring lines.
The constant voltage source circuit may further comprise: a first compensation circuit comprising a second resistor, a second inductance unit and a second bypass capacitor, one end of each of the second resistor, the second inductance unit and the second bypass capacitor being coupled to each other, wherein the other end of the second resistor is coupled to an end of the first inductance unit near the constant voltage supplying circuit, the other end of the second inductance unit is coupled to a load side end of the first inductance unit and the other
Advantest Corporation
Han Jessica
Osha Novak & May L.L.P.
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