| 摘要 |
PURPOSE: An AFE(Analog Front End) of an ADSL(Asymmetrical Digital Subscriber Line) system is provided to make an ADSL interface of a DSLAM(Digital Subscriber Line Access Multiplexer) implement a device for performing a transmit/receive path filtering inside of the AFE, so as to stably process analog signals to reduce power consumption and noises. CONSTITUTION: A D/A converter)(41) converts a 14-bit parallel-typed digital ADSL signal into an analog signal, and outputs the analog signal to an external HPF(High Pass Filter)(42). The digital ADSL signal is DMT(Discrete Multi Tone)-modulated in a DMT processor(35). An LPF(Low Pass Filter)(43) removes a noise from the analog signal inputted via the HPF(42). If an analog signal outputted from a line driver/receiver(37) is inputted via an external LPF(44) and an HPF(45), a PGA(Programmable Gain Amplifier)(46) amplifies a gain of the analog signal. An LPF(47) removes a noise from the gain-amplified analog signal, and outputs the noise-removed analog signal to an A/D converter buffer(48). An A/D converter(49) converts the analog signal inputted via the A/D converter buffer(48) into a 12-bit parallel-typed digital ADSL signal, and outputs the digital ADSL signal to the DMT processor(35).
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