AUTOMATIC GAIN CONTROL CIRCUIT AND LOW NOISE AMPLIFIER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To obtain desired input sensitivity by preventing the noise index of an LNA from being deteriorated in a circuit configuration provided with a bypass switch for a high-frequency amplifier circuit. SOLUTION: An antenna damping circuit 4 is connected in series to the bypass switch 5 and the serial circuit is connected in parallel to the LNA 3. This configuration can prevent a signal path from connecting the bypass switch 5 in series to the LNA 3 when the LNA 3 operates, and prevent deterioration of the noise index of the LNA 3 due to ON-resistance of the bypass switch 5. COPYRIGHT: (C)2008,JPO&INPIT