LA1193M Sanyo Semicon Device, LA1193M Datasheet - Page 9

• Manufacturer Part Number: LA1193M
• Description: High-Performance FM Front End for Car Radios
• Manufacturer: Sanyo Semicon Device

• Two-Signal Sensitivity Suppression Characteristics
This double wide-band AGC system consists of two AGC circuits and a narrow AGC (pin 13 input, mixer input
detection type) as shown in Figure 1. Figure 2 shows the antenna input frequency characteristics.
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
— Since this system uses a narrow AGC at the same time, the wide AGC sensitivity can be lowered, thus
— Optimal sensitivities for any field conditions can be set, since the sensitivities of both the wide and narrow
— The input level of the desired station is limited by the narrow AGC. As a result, excessive levels are no longer
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.
interfering stations with ∆f > 1 MHz. (TV band interference prevention)
preventing incorrect operation due to local oscillator injection.
AGC systems can be set by changing the values of external components.
input to the stages that follow the mixer and the beats at multiples of 10.7 A are reduced.
RF and antenna circuit information
Mixer circuit information
C, F and selectivity information
Figure 2 AGC Sensitivity Detuning Characteristics
LA1193M, 1193V
Mixer input AGC
Mixer output AGC
S-meter output
Three
dimensions
No. 4715-9/21