| 摘要 |
PURPOSE: An apparatus for supplying a local frequency in a mobile communication system is provided so that the local frequency can be stably supplied to an up/down converter by constantly maintaining a signal level of each PLL module, when an output level of a local signal is seriously changed due to property difference of the PLL modules. CONSTITUTION: A PLL module(100) generates a local frequency and outputs the local frequency to a variable attenuator(300). The first condenser(200) is connected to a signal output terminal of the PLL module(100), for removing DC elements from the local frequency from the PLL module(100), and outputting the local frequency to the variable attenuator(300). The variable attenuator(300) receives the local frequency from the PLL module(100), attenuates a level of the local frequency to a predetermined level, and outputs the local frequency to an up/down converter(1). A variable resistance(R1) is connected to the signal output terminal of the PLL module(100), for adjusting the level of the local frequency to a predetermined level. Resistances(R2,R3) have the same time constant. The second condenser(400) is connected to the variable resistance(R1) of the variable attenuator(300), for removing the DC elements of the local frequency from the variable attenuator(300), and outputting the local frequency to the up/down converter(1).
|
