| 摘要 |
PURPOSE: An automatic gain controller for reducing power loss through precise gain control around a maximum gain while obtaining an SNR(Signal to Noise Ratio) to the maximum, a transmission device of a mobile communication terminal having the automatic gain controller and a method thereof are provided to make a gain inclination of an RF amplifier changed according to a control voltage bigger than a gain inclination of an IF amplifier, and to make an IF gain bigger than an RF gain. CONSTITUTION: A VIC(Voltage-Current Converter)(321) generates a current proportional to a control voltage by responding to the control voltage, and outputs the current. An exponential function current generator(323) outputs a bias 2 which converts the current proportional to the control voltage into a current which exponentially and functionally changes, and outputs a bias 3 which is a remaining current except the bias 2. The first linear gain control unit(325) generates an IF gain control signal for controlling an IF amplifier to show the first linear gain properties, and outputs the generated IF gain control signal. The second linear gain control unit(327) generates an RF gain control signal for controlling an RF amplifier to show the second linear gain properties, and outputs the generated RF gain control signal. |
