| 摘要 |
PURPOSE: A frequency upconverter in a base station in a mobile system is provided to solve unstableness for temperature by designing a symmetrically operating Pi attenuator using a thermistor and to improve the transmitting signal performance of a base station system by adding a signal level adjustment function and a compulsory impedance matching function. CONSTITUTION: The first thermistor-type Pi attenuator(100), stable for variation of temperature, converts a 155MHz transmitting frequency into a desired signal level. The first LPF(Low Pass Filter)(110) executes low pass filtering for the output signal of the first thermistor-type Pi attenuator(100). The second thermistor-type Pi attenuator(120), stable for variation of temperature, converts the frequency outputted from the first LPF(110) into a desired signal level. The first VCO(Voltage Controlled Oscillator)(130) generates a local signal. The first mixer(140) mixes the frequency outputted from the second thermistor-type Pi attenuator(120) with the local signal outputted from the first VCO(130). The third thermistor-type Pi attenuator(150), stable for variation of temperature, converts the frequency outputted from the first mixer(140) into a desired signal level. The first band pass filter(160) filters the frequency signal outputted from the third thermistor-type Pi attenuator(150). An attenuator(170) attenuates the signal outputted from the first band pass filter(160). The first amplifier(180) amplifies the signal outputted from the attenuator(170). A tuning attenuator(190) executes tuning attenuation for the signal outputted from the first amplifier(180).
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