Patent ID: 7298426

Claim:
A television tuner comprising: a first field-effect transistor for amplifying a television signal of a first frequency, the first field-effect transistor being disposed inside the television tuner; a second field-effect transistor for amplifying a television signal of a second frequency, the second field-effect transistor being disposed inside the television tuner; and an integrated circuit, the integrated circuit including a grounding terminal coupled to the sources of the first and second field-effect transistors; a first input terminal for inputting the television signal of a first frequency, the first input terminal being coupled to a first gate of the first field-effect transistor; and a second input terminal for inputting the television signal of a second frequency, the second input terminal being coupled to a first gate of the second field-effect transistor; wherein a switching transistor having an emitter coupled to the grounding terminal, a first resistor disposed between the first gate of the first field-effect transistor and the grounding terminal, a second resistor disposed between the first gate of the first field-effect transistor and a collector of the switching transistor, a third resistor disposed between the collector of the switching transistor and a drain of the first or second field-effect transistor, and a fourth resistor disposed between a base of the switching transistor and the first gate of the second field-effect transistor are disposed inside the integrated circuit, wherein a power-supply voltage is appliable to the drains of the first and second field-effect transistors, wherein an automatic gain control voltage is appliable to second gates of the first and second field-effect transistors, wherein a bias voltage is appliable to the second input terminal via a fifth resistor from outside of the integrated circuit when the television signal of a second frequency is received, and wherein a voltage is appliable to a bias voltage terminal from outside the integrated circuit via a sixth resistor, the bias voltage terminal being coupled to the collector of the switching transistor.