LA1175 データシートの表示（PDF） - SANYO -> Panasonic

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LA1175

FM front end for car radio, home stereo application

SANYO -> Panasonic 

LA1175, 1175M

Temperature Characteristic (7)

Temperature Characteristic (7)

Ambient temperature, Ta – °C

Temperature Characteristic (7)

Ambient temperature, Ta – °C

Ambient temperature, Ta – °C

Description of AGC circuit in the LA1175, 1175M

The LA1175, 1175M are designed so that AGC is operated in the order shown below.

ANT damping (PIN diode) → MOS FET 2nd gate voltage control

(Attenuation)20dB

(Attenuation)60dB

The following are the reasons why AGC is operated in this order.

(1) When a signal of 110dBµ or greater is applied to the varactor in the ANT circuit, intermodulation may occur. In

this case, if AGC is operated in the order of MOS FET 2nd gate control AGC → ANT damping (PIN diode), the

input to the varactor in the ANT circuit is not restricted unless a strong signal with AGC attenuation 60dB or

greater is given. Therefore, AGC should be operated in the order shown above.

(2) If the two AGC loops (AGC loop (ANT damping) and AGC loop (MOS FET 2nd gate control)) are operated

simultaneously, the transient response of AGC loses stability. Therefore, the order shown below is

impracticable.

MOS FET 2nd gate control → ANT damping → MOS FET 2nd gate control.

No.2276-13/14

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