LA1193M Просмотр технического описания (PDF) - SANYO -> Panasonic

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LA1193M

For Car Radios High-Performance FM Front End

SANYO -> Panasonic 

LA1193M, 1193V

Features of the Double Wide AGC System

— Since this is a mixer input detection wide-band AGC, it prevents the occurrence of intermodulation due to

interfering stations with ∆f > 1MHz. (TV band interference prevention)

— Since this system uses a narrow AGC at the same time, the wide AGC sensitivity can be lowered, thus preventing

incorrect operation due to local oscillator injection.

— Optimal sensitivities for any field conditions can be set, since the sensitivities of both the wide and narrow AGC

systems can be set by changing the values of external components.

— The input level of the desired station is limited by the narrow AGC. As a result, excessive levels are no longer input

to the stages that follow the mixer and the beats at multiples of 10.7 × A are reduced.

• Two-Signal Sensitivity Suppression Characteristics

Previously, keyed AGC systems were used to provide good intermodulation distortion and two signal sensitivity

suppression characteristics at the same time. However, in previous keyed AGC systems, when the desired station

would fade or drop out, the wide band AGC level would become essentially zero. As a result, the automatic station

selection function would malfunction and blocking oscillation would occur in the presence of strong interfering

stations. Thus keyed AGC systems were extremely hard to use in actual practice. Sanyo has developed a new AGC

system (3D-AGC) that solves these problems and allows the construction of extremely simple application circuits.

The LA1193M/V incorporates this AGC system.

What is the 3D-AGC system?

It is a system that determines the wide-band AGC level by using information that has the following three frequency

characteristics.

RF and antenna circuit information Mixer input AGC

Mixer circuit information

Mixer output AGC

C, F and selectivity information S-meter output

Three

dimensions

3D-AGC Features

Feature

The narrow AGC sensitivity, which operates for ∆f of less than 1.5MHz, is

controlled independently according to the field strength of the desired

station.

The narrow AGC sensitivity is controlled at V20 values under 2V.

The wide AGC operates even when V20 is zero, i.e., when the desired

station does not exist.

The N-AGC and the W-AGC sensitivities can be set independently.

The system has two AGC systems, the N-AGC and the W-AGC.

Merit

• This is effective as a measure for mitigating two signal sensitivity

suppression.

• This allows two signal sensitivity suppression to be mitigated without

deterioration in the three signal characteristics.

• This allows the prevention of incorrect stopping on intermodulation

signals during search.

• This allows the prevention of intermodulation occurring in the

antenna and RF modulation circuits in the presence of strong

interfering stations. Prevention of blocking oscillation due to AGC

operation is also possible.

• This allows optimal settings to match the reception field conditions.

• Since the narrow AGC operates at the desired station and at

adjacent stations, it is possible to reduce the wide AGC sensitivity.

This prevents incorrect AGC operation due to local oscillator

injection.

No.4715-10/22

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