Power supply noise measuring circuit and power supply noise measuring method
First Claim
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1. A power-supply noise measuring circuit comprising:
- a voltage fluctuation detecting circuit that generates a detection current in accordance with a voltage fluctuation of a power supply;
a unit time generating circuit that generates a unit time in accordance with a clock signal;
a current measuring circuit that measures an amount of the detection current per the unit time; and
a sampling circuit that samples the amount of the detection current measured by the current measuring circuit per the unit time;
wherein the current measuring circuit includes;
a current accumulating circuit that accumulates the detection current;
an accumulation determination circuit that determines that an amount of charge accumulated at the current accumulating circuit exceeds a predetermined threshold value, and outputs a determination signal; and
a counter circuit that starts to count a number of pulses of the determination signal in response to the output of the determination signal.
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Abstract
A power-supply noise measuring circuit includes a voltage fluctuation detecting circuit, a unit time generating circuit, a current measuring circuit, and a sampling circuit. The voltage fluctuation detecting circuit generates a detection current in accordance with a voltage fluctuation of a power supply. The unit time generating circuit generates a unit time in accordance with a clock signal. The current measuring circuit treasures an amount of the detection current per unit time. The sampling circuit samples the amount of the detection current measured by the current measuring circuit, every unit time. The present invention provides the power-supply noise measuring circuit that has a small circuit area and enough accuracy.
11 Citations
8 Claims
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1. A power-supply noise measuring circuit comprising:
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a voltage fluctuation detecting circuit that generates a detection current in accordance with a voltage fluctuation of a power supply; a unit time generating circuit that generates a unit time in accordance with a clock signal; a current measuring circuit that measures an amount of the detection current per the unit time; and a sampling circuit that samples the amount of the detection current measured by the current measuring circuit per the unit time; wherein the current measuring circuit includes; a current accumulating circuit that accumulates the detection current; an accumulation determination circuit that determines that an amount of charge accumulated at the current accumulating circuit exceeds a predetermined threshold value, and outputs a determination signal; and a counter circuit that starts to count a number of pulses of the determination signal in response to the output of the determination signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A power-supply noise measuring circuit comprising:
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a voltage fluctuation detecting circuit that generates a detection current in accordance with a voltage fluctuation of a power supply; a unit time generating circuit that generates a unit time in accordance with a clock signal; a current measuring circuit that measures an amount of the detection current per the unit time; a sampling circuit that samples the amount of the detection current measured by the current measuring circuit per the unit time; and an initial value storing circuit that stores a sampling value sampled at an initialization sequence as an initial value, wherein a difference between the sampling value sampled at an normal operation and the initial value is obtained as an amount of power-supply noise.
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Specification
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Current AssigneeNEC Corporation
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Original AssigneeNEC Corporation
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InventorsKajita, Mikihiro
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Primary Examiner(s)Vazquez, Arleen M
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Assistant Examiner(s)LE, THANG XUAN
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Application NumberUS12/797,943Publication NumberTime in Patent Office1,188 DaysField of Search324/613US Class Current324/613CPC Class CodesG01R 29/26 Measuring noise figure; Mea...G01R 31/40 Testing power supplies test...
