Power supply noise measuring device
AssigneeNEC Corporation
InventorMikihiro Kajita
Life of this patent
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Abstract
According to one embodiment, a signal from a power supply line is caused to pass through a high pass filter, and a first signal is generated by adding a voltage-divided signal to the signal. In addition, a second signal obtained by adding the voltage-divided signal to an identification voltage is generated. A comparator outputs a comparison result of comparing a voltage of the first signal with a voltage of the second signal, and a counter counts up a count value when the voltage of the first signal is higher than that of the second signal. A sample hold circuit sample-holds the count value just before the counter is reset.
Claims32
A power supply noise measuring device comprising:
- a high pass filter that inputs a power supply signal from a power supply line, and that outputs a signal obtained by removing components having frequencies equal to or lower than a predetermined frequency from the input power supply signal;
- a first adder that generates a signal by adding a first direct-current signal to the signal output from the high pass filter;
- a comparator that compares a voltage of the signal output from the first adder with a reference voltage;
- a counter that performs a counting operation controlled according to a comparison result of the comparator, and that is reset in a predetermined cycle;
- and
- a sample hold circuit that sample-holds a count value of the counter just before the counter is reset.
A power supply noise measuring method comprising the steps of:
- causing a high pass filter to input a power supply signal from a power supply line, and to output a signal obtained by removing components having frequencies equal to or lower than a predetermined frequency from the input power supply signal;
- causing a first adder to generate a signal by adding a first direct-current signal to the signal output from the high pass filter;
- causing a comparator to compare a voltage of the signal output from the first adder with a reference voltage;
- causing a counter to perform a counting operation controlled according to a comparison result of the comparator, and to be reset in a predetermined cycle;
- and
- causing a sample hold circuit to sample-hold a count value of the counter just before the counter is reset.
Dependencies are inferred from the claim text.