| 摘要 |
PURPOSE: A low frequency noise exclusion circuit is provided to prevent the distortion and saturation of signals by eliminating noise signals included in signals outputted from IF amplifier. CONSTITUTION: A low frequency noise exclusion circuit(100) is composed of the third low pass filter(110) and an adder(120). The third pass filter(110) passes only low frequency noise signals, making middle frequency outputted from automatic gain controller(15) get feedback. The adder eliminates noise signals included in wireless frequency outputted from IF amplifier(27), after adding wireless frequency from IF amplifier(27) to low frequency noise signals. A logic block(12) creates continuous wave of voltage type and outputs continuous wave to a D/A convertor(13), when DSP(11) of a signal processing part(10) outputs globular wave. The D/A convertor(13) converts digital signals into analog signals and outputs the analog signals to the first low pass filter(14). The first low pass filter(14) passes only signals of band to want pass.
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