RF CUT-OFF DEVICE, PARTICULARLY CORRELATED TO REMOVING A TDMA NOISE CAUSED BY AN RF INTERFERENCE GENERATED FROM A MICROPHONE AND A SPEAKER OF A TERMINAL

摘要

PURPOSE: An RF cut-off device is provided to connect an RF cut-off bead or a varistor with a microphone and a speaker in serial or in parallel, so as to attenuate a GSM frequency band, thereby removing a TDMA noise caused by an RF interference of the GSM frequency band. CONSTITUTION: A bead(B1) is connected to the first output contact of a microphone(100) in serial. A bead(B2) is connected to the second output contact of the microphone(100) in serial. The beads(B1,B2) connected to each output contact of the microphone(100) in serial have high impedance values in a GSM frequency band. When the RF cut-off beads(B1,B2) are connected to the microphone(100) in serial, impedance of the RF cut-off beads(B1,B2) remarkably gets higher in the GSM frequency band while the impedance gets lower in the rest frequency bands.