Patent ID: 6501338
Filing Date: 2002-12-31
Classification: H03B

Abstract:
A three-band switching oscillator comprising:a first voltage-controlled oscillator switched to oscillate in one of a first and second frequency band; a second voltage-controlled oscillator designed to oscillate in a third frequency band; and a switching circuit to switch said first and second voltage-controlled oscillators to one of an operative condition and an inoperative condition and to switch an oscillation frequency band of said first voltage-controlled oscillator, said switching circuit including: a first switch to supply a current to place said first voltage-controlled oscillator into the operative condition; a second switch to supply a current to place said second voltage-controlled oscillator into the operative condition; and first and second switching terminals to receive switching voltages, wherein said first switch is placed into one of an open and closed condition in accordance with one of a first low-level and first high-level switching voltage, respectively, inputted to said first switching terminal and the oscillation frequency band is switched in accordance with one of a second high-level and second low-level switching voltage inputted to said second switching terminal, while only when the second high-level switching voltage is inputted to said second switching terminal, said second switch is placed into an open condition by the first high-level switching voltage inputted to said first switching terminal and placed into a closed condition by the first low-level switching voltage inputted thereto, and when the second low-level switching voltage is inputted to said second switching terminal, said second switch is placed into the open condition irrespective of the switching voltage inputted to said first switching terminal.