| 摘要 |
A tuner for receiving digital cable broadcasting is provided to detect the gain of multi-channel digital cable broadcasting signals amplified and outputted from an LNA from a cable antenna and operate an AGC circuit so as for the gain-controlled multi-channel digital cable broadcasting signals to be inputted to the LNA if the gain of the multi-channel digital cable broadcasting signals is more than a preset gain level, thereby preventing the saturation of the LNA and preventing the generation of harmonics caused by the saturation of the LNA. A tuner comprises an LNA(Low Noise Amplifier)(21), an input tuning circuit(23), a high frequency gain control amplifier(24), an inter-stage tuning circuit(25), a mixer(26), a filter(27), an AGC(Auto Gain Control) circuit(20), and an auto gain level detecting circuit(22). The AGC circuit controls the gain of a digital cable signal inputted from a cable antenna(ANT). The auto gain level detecting circuit operates the AGC circuit to control the gain of multi-channel digital cable broadcasting signals inputted from the cable antenna if the gain level of a detected signal is higher than a preset gain level.
|
