| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply which is included or assembled in electronic equipment at low cost in a simple circuital structure with no noises in all the frequency range for an electronic apparatus, without enlarging the whole body or covering a switching power supply unit with a shield member that deteriorates efficiency in heat. SOLUTION: In a switching power supply, a noise factor as an output from a receiving unit made up of an antenna 1, a high-frequency circuit 2, a mixing circuit 3, a local oscillation circuit 4, and an intermediate frequency circuit 5 is extracted through a bypass filter 36, held by a peak holding circuit 37, and compared with an output of a reference power supply 39 by using a comparator 38. When there are a large number of noise factors and the comparator 38 is operated, a switch 40 is turned on, and a load resistor 41 is connected to a switching power supply 42 to increase additional current. Then, the switching frequency of the switching power supply 42 is made to be higher under control, so as to reduce the noise factor. |
