US 7,405,574 B2Granted

Signal detector

AssigneeTDK Corporation

InventorYoshihiro Saitoh

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Abstract

A signal suppression filter (22) that inhibits high-frequency signals contained in power voltage and a signal separation filter (23) that prevents transmission of the high-frequency signals are provided in series on power lines (21A), (21B) connected to a power input terminal (T1), and a common-mode signal detection circuit (25) and a normal-mode signal detection circuit (26) are provided separately from each other. While bi-directionally blocking transmission of a high-frequency signal (noise) between the power supply and the device to be measured by the signal suppression filter (22) and the signal separation filter (23), the common mode signal and the normal mode signal generated in the device to be measured (3) and entering through a power output terminal (T2) are detecting separately. The analysis of the cause of occurrence of a high-frequency signal produced in the device to be measured (3) is facilitated, and proper noise countermeasure may be taken.

Claims10

Dependent claims

A signal detector comprising:

a power input terminal supplied with power voltage from a power supply source;
a power output terminal connected to a device to be measured, and outputting the power voltage inputted from the power input terminal to the device to be measured;
a signal blocking circuit provided on first and second conductive lines connected to the power input terminal, and blocking transmission of a signal between the power input terminal and the power output terminal;
a common-mode signal detection circuit extracting a common mode signal from signals contained in the power voltage between the power output terminal and the signal blocking circuit;
a normal-mode signal detection circuit extracting a normal mode signal from the signals contained in the power voltage between the power output terminal and the signal blocking circuit;
a common-mode signal output terminal provided at an output end of the common-mode signal detection circuit;
and
a normal-mode signal output terminal provided at an output end of the normal-mode signal detection circuit.

5 more elements

Dependencies are inferred from the claim text.