Abstract: A noise suppressing circuit comprises: windings (W11, W12) inserted to conductor lines (3, 4) at respective points (P11a, P11b) and coupled to each other through a magnetic core (11); a winding (W13) coupled to the windings (W11, W12) through the core (11); capacitors (12, 13) having ends connected to the conductor lines (3, 4) at respective points (P12a, P12b) and the other ends connected to an end of the winding (W13); and windings (W14, W15) inserted to conductor lines (3, 4) at respective points (P13a, P13b) and coupled to each other through a magnetic core (14). These components reduce common mode noise. Capacitors (16, 17) reduce normal mode noise in cooperation with leakage inductances produced by the windings (W14, W15).

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.

Abstract: A noise suppressing circuit (1) suppresses noise emerging from an electronic apparatus (2) and propagating through conductive lines (3a and 3b). The noise suppressing circuit (1) comprises a low-band noise reducing circuit (10) and a high-band noise reducing circuit (80). The low-band noise reducing circuit (10) is connected to the electronic apparatus (2) through the conductive lines (3a and 3b). The high-band noise reducing circuit (80) is cascade-connected to the low-band noise reducing circuit (10) and connected to conductive lines (4a and 4b) of a power line (4).

Abstract: A small and inexpensive signal detector is provided, which can be simply used for noise detection as a development tool for development engineers of systems and devices. A signal suppression filter (22) of inhibiting high-frequency signals contained in power voltage and a signal separation filter (23) of inhibiting transmission of the high-frequency signals are provided in series in power lines (21A), (21B) connected to a power input terminal (T1), and high-frequency signals contained in power voltage between a power output terminal (T2) and the signal separation filter (23) are outputted from signal output terminals (T3) to (T5). High-frequency signals from a power source can be blocked by the signal suppression filter (22) and the signal separation filter (23), so that influence of power noise on a measurement system can be eliminated.

Abstract: A signal detector having an excellent measurement capability that enables simple and accurate cause analysis of noise generation is provided. 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.

Abstract: A common mode signal suppressing circuit comprises: a first winding (11) inserted to a conductor line (3); a second winding (12) that is inserted to a conductor line (4) and coupled to the first winding (11) through a magnetic core (10) and that suppresses common mode signals in cooperation with the first winding (11); and a third winding (13) coupled to the first and second windings (11, 12) through the core (10). The common mode signal suppressing circuit further comprises a phase-inverted signal transmitting circuit (15) connected to the third winding (13) and to the conductor lines (3, 4). The phase-inverted signal transmitting circuit (15) detects a common mode signal on the conductor lines (3, 4), and supplies a phase-inverted signal to the third winding (13), the phase-inverted signal having a phase opposite to the phase of the common mode signal.

Abstract: A normal mode noise suppressing circuit comprises: a noise suppressing section (10) provided on conductor lines (3, 4); and a capacitor (31) having an end connected to the conductor line (3) and the other end connected to the conductor line (4). The noise suppressing section (10) comprises: a winding (15a) inserted to the conductor line (3); a winding (15b) coupled to the winding (15a) through a magnetic core (15c); an injection signal transmission path (19); a capacitor (16); and an inductance element (18). The injection signal transmission path (19) has an end connected to the conductor line (3) and the other end connected to the conductor line (4). The winding (15b) and the capacitor (16) are inserted somewhere along the injection signal transmission path (19). The inductance element (18) is inserted to the conductor line (3) at a point between the winding (15a) and the node between the injection signal transmission path (19) and the conductor line (3).

Abstract: A modem for power-line communications (20A) comprises input/output terminals (71a and 71b) and input/output terminals (72a to 72d). The input/output terminals (71a and 71b) are connected to a power line and perform input and output of power-line communications signals. The input/output terminals (72a to 72d) perform input and output of data signals from and to a communications apparatus through a cable. The modem (20A) further comprises: a modem main body (73); a common mode filter (80) provided between the modem main body (73) and the input/output terminals (71a and 71b); and a common mode filter (90) provided between the modem main body (73) and the input/output terminals (72a to 72d).

Abstract: A noise suppressing circuit (1) suppresses noise emerging from an electronic apparatus (2) and propagating through conductive lines (3a and 3b). The noise suppressing circuit (1) comprises a low-band noise reducing circuit (10) and a high-band noise reducing circuit (80). The low-band noise reducing circuit (10) is connected to the electronic apparatus (2) through the conductive lines (3a and 3b). The high-band noise reducing circuit (80) is cascade-connected to the low-band noise reducing circuit (10) and connected to conductive lines (4a and 4b) of a power line (4).

Abstract: A common mode signal suppressing circuit comprises: a first winding (11) inserted to a conductor line (3); a second winding (12) that is inserted to a conductor line (4) and coupled to the first winding (11) through a magnetic core (10) and that suppresses common mode signals in cooperation with the first winding (11); and a third winding (13) coupled to the first and second windings (11, 12) through the core (10). The common mode signal suppressing circuit further comprises a phase-inverted signal transmitting circuit (15) connected to the third winding (13) and to the conductor lines (3, 4). The phase-inverted signal transmitting circuit (15) detects a common mode signal on the conductor lines (3, 4), and supplies a phase-inverted signal to the third winding (13), the phase-inverted signal having a phase opposite to the phase of the common mode signal.