| 摘要 |
PURPOSE: A squelch circuit is provided to reduce a costs of a radio frequency portion used in a wireless communication system and an adjustment number, by using a fixed resistor when adjusting the squelch circuit according to a noise level. CONSTITUTION: The first transistor(Q1) has an emitter connected to a ground terminal and a base connected to DEMOD IC. The second transistor(Q2) has a base connected to a collector of the first transistor(Q1) through a resistor(R4) and to a power supply voltage(VCC) through resistors(R4, R3), a collector connected to the power supply voltage(VCC) via a resistor(R6), and an emitter connected to the ground voltage via a resistor(R5). A fixed resistor part(R1, R2) is connected to the base of the first transistor(Q1) and the DEMOD IC. The first capacitor(C1) is connected in series with the IC. The second capacitor(C2) is connected between the power supply voltage(VCC) and the ground voltage(GND).
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