Patent ID: 6226503
Filing Date: 2001-05-01
Classification: H03J

Abstract:
A double-tuned circuit comprising:a primary tuning a circuit having a high-band tuning coil and a low-band tuning coil connected in series at one end of each coil;a secondary tuning circuit having a high-band tuning coil and a low-band tuning coil connected in series at one end of each coil;a first coupling coil disposed between the ground and a connection point where the other end of the low-band turning coil in said primary tuning circuit is connected to the other end of the low-band tuning coil in said secondary tuning circuit;a first switch diode and a second switch diode connected in series disposed between the one end of the high-band tuning coil in said primary tuning circuit and the one end of the high-band tuning coil in said secondary tuning circuit;a second coupling coil disposed between the ground and the connection point of said first switch diode and said second switch diode,wherein, when a high-band television signal is received, said first switch diode and said second switch diode are set to a continuity state, and when a low-band television signal is received, said first switch diode and said second switch diode are set to non-continuity state; anda first switching terminal and a second switching terminal,wherein said first switch diode and said second switch diode are connected in series by their anodes or by their cathodes;the anodes are connected to said first switching terminal in a DC-coupling mannerthe cathodes are connected to said second switching terminal in a DC-coupling manner; andsaid first switch diode and said second switch diode are set to the continuity state and the non-continuity state by a band switching voltage applied to said first switching terminal and said second switching terminal.