Patent ID: 7852177

Claim:
A double-tuning circuit of a television tuner, the double-tuning circuit comprising: a primary tuning circuit in which a first inductor is connected in parallel with a first variable capacitive element; a secondary tuning circuit in which a second inductor is connected in parallel with a second variable capacitive element, the second inductor being inductively coupled to the first inductor; a coupling capacitor connected in series between a hot-side output terminal of the secondary tuning circuit and an input terminal of a downstream circuit; a pattern used to form a trap circuit for attenuating an image frequency component of a received television signal, the trap circuit being formed to have an infinitesimal capacitance generated between a tip part of the pattern and the first inductor when a fixed part of the pattern is connected to a connection point at which the coupling capacitor is connected to the input terminal of the downstream circuit and the tip part of the pattern extends to near the first inductor; a third inductor formed between a ground-side terminal of the first inductor and a ground; a first capacitor connected between a connection point at which the first inductor is connected to the third inductor and a ground-side terminal of the second variable capacitive element; and a second capacitor connected between a ground-side terminal of the second variable capacitive element and the ground.