Abstract: An apparatus comprises a condenser such as a condenser for reducing power source noise to be implemented on a board, a conductor for supplying a current passing through the condenser, and a current path comprising conductors and components which are installed in the neighborhood of at least one of the condenser and conductor and the effective inductance component of the condenser is reduced by passing a current through the current path in the phase opposite to that of a current passing through the condenser and conductor.

Abstract: A multiprocessor system is provided with processor units which are grouped beforehand into some groups, a system status monitoring unit for monitoring a key input operation of a keyboard, a power demand monitoring unit for calculating the difference between the total power demand of the processor units at the present time and the total power demand of the processor units in a low power-demand mode which is measured beforehand, when the key input operation is not carried out in a normal operation mode for a predetermined time, and an operation clock controller for successively reducing or stopping operation clocks supplied to the respective processor units for each group in turn to shift the current mode to the low power-demand mode. With this construction, a power variation which occurs at the time of the switching operation between the normal operation mode and the low power-demand mode or at the time of power supply/power shut-off can be reduced.

Abstract: A shielding method which utilizes a three dimensional structure and is effective to a source of the electromagnetic radiation noise, and a circuit board employing the same are obtained. Further, for the purpose of making the shielding function at an enclosure level unnecessary and realizing the recycling of enclosure materials by using this circuit board, in a circuit board structure having at least a signal layer, a power source layer and a ground layer, a signal line on the signal layer which is sandwiched between the two conductor layers made up of the power source layer and the ground layer, or the power source layers or the ground layers, is enclosed in a three dimensional manner with the conductor layers, thereby to form a single or double electrical closed loop current path or paths. By adopting this structure, there is obtained the effect that the electromagnetic radiation noise radiated from the circuit board is greatly reduced.

Abstract: A semiconductor apparatus comprises a heat diffusing plate and a surface installing printed board. A semiconductor device of a high heat generation is installed on the heat diffusing plate. A surface installing package and chip parts are installed on both surfaces of the printed board. A through hole is formed at the center of the printed board so that the semiconductor device is located at the center. The heat diffusing plate on which the semiconductor device has been installed and the surface installing printed board are connected and integrated.