| 摘要 |
PURPOSE: To decrease the number of components and to attain the transmission, processing and conversion of plural video signals due to mutually different transmission standard systems by switching one oscillator between two oscillation frequencies and tuning these frequencies. CONSTITUTION: Power is supplied to 1st and 2nd switching diodes 25 and 26 by controllable current sources 27, 28, 29 and 30. The diodes 25 and 26 are conducted by applying DC currents to them while switching on/off the current sources 27-30 or the diodes 25 and 26 are turned off by turning the current sources 27-30 into no current state. In the former case, 2nd frequency determining elements 23 and 24 are parallelly connected with 1st frequency determining elements 13-16 and an oscillator 1 is switched to the 2nd oscillation frequency. In the latter case, this parallel connection is cut off and the oscillator 1 is operated at the 1st oscillation frequency. |
