| 摘要 |
A satellite digital tuner is provided to maintain signal reception sensitivity stable by reducing an interference between an amplified high frequency signal and signals in other frequency bands. A satellite digital tuner includes a variable HPF(High Pass Filter)(21), an LNA(Low Noise Amplifier)(22), a high frequency automatic gain amplifier circuit(23), and a demodulator(25). The variable HPF performs filtering a high frequency signal using a desired pass band. The LNA removes a noise from the filtered frequency and amplifies the result. The high frequency automatic gain amplifier circuit adjusts a reception gain by using an automatic gain adjusting signal, which is fed back from the LNA. An I/Q converting circuit mixes the result from the high frequency automatic gain amplifier circuit with a local oscillator frequency and outputs an intermediate frequency signal. The demodulator demodulates the I/Q signal to obtain original video and audio digital data. |
