Abstract: A multilayer circuit board having a signal and power isolation circuit, which can suppress the capacitive coupling between a chip inductor and a ground layer below the chip inductor and also suppress the characteristic impedance change occurring in a mounting pad on a microstrip line. Portions of the inner-layer ground below both the mounting pad on the microstrip line and the chip inductors connected to the mounting pad are separately removed respectively as the signal transmission characteristic compensation removal portion, which is formed by removing a portion having a predetermined area and situated immediately below the mounting pad, and the inductor characteristic compensation removal portion, which is formed by removing a mounting-surface-below portion having a predetermined area and situated immediately below the chip inductors.

Abstract: A transmission system capable of improving transmission characteristics in a low frequency range and having reduced size. A transmission system for superimposing power on a signal transmission path between a first circuit module and a second circuit module includes a first capacitor between the transmission path and a first interface IC in the first circuit module, a second capacitor between the transmission path and a second interface IC in the second circuit module, a first inductor between a first power supply circuit in the first circuit module and the transmission path, and a second inductor between a second power supply circuit in the second circuit module and the transmission path. A capacitance value of the first capacitor and a capacitance value of the second capacitor differ from each other. Inductance values of each of the first and second inductors are in a range from 20 [?H] to 50 [?H].

Abstract: An electronic circuit includes a shield line including first and second signal lines and a shield. The first and second signal lines are connected to a signal source, and the shield coating is around the first and second signal lines. The electronic circuit further includes a signal ground near the signal source; a frame ground that is isolated from the signal ground and connected to the shield; a common mode choke coil that includes first, second and third coils magnetically coupled to one another; and a capacitor that is connected in parallel with the third coil. The first coil is connected in series between the signal source and the first signal line. The second coil is connected in series between the signal source and the second signal line. The third coil and the capacitor that are connected in parallel are connected between the signal ground and the frame ground.