LA1193M_08 SANYO [Sanyo Semicon Device], LA1193M_08 Datasheet - Page 12

• Manufacturer Part Number: LA1193M_08
• Description: High-Performance FM Front End
• Manufacturer: SANYO [Sanyo Semicon Device]

5. IF Amplifier
Gain adjustment can be provided using either of the methods shown.
Temperature Characteristics
6. AGC Circuit
This IF amplifier is a single stage differential amplifier.
Specifications
IF Gain adj
The LA1193M/V uses Vref temperature characteristics correction to hold the gain temperature characteristics to the
low level of about 1dB over the range −30 to +80°C.
The LA1193M/V uses pin diode antenna damping (pin 9) and MOSFET second gate voltage control (pin 16) for AGC.
The AGC operating sequence is as follows :
Antenna damping (pin diode) → MOSFET second gate voltage control
The above AGC sequence is used for the following reasons.
• Intermodulation distortion can occur if a signal of 110dBµ or larger is input to the antenna circuit varactor diode.
• Consider the problem of AGC loop stability. If the two AGC loops (the antenna damping AGC loop and the MOSFET
• Narrow AGC circuit
• The AGC sensitivity setting can be changed by adjusting the
Since the LA1193M/V’s N-AGC (which detects the mixer output) is set to have a high sensitivity, care is required to
avoid incorrect operation. In particular, there must be adequate separation from the local oscillator block on the
printed circuit board pattern. Also, a resistor of at least 500Ω must be inserted at the pin 13 input. A low-pass filter is
formed by the insertion of this resistor. This low-pass filter prevents incorrect AGC operation due to the local
oscillator.
value of the capacitor connected at pin 13. Although the AGC
sensitivity can be lowered by increasing the value of the series
resistor, caution is required since the AGC has its own frequency
characteristics.
In such situations, if the AGC sequence was MOSFET second gate voltage control followed by pin diode antenna
damping, as long as the receiver was not in a strong field where the 60dB or higher AGC attenuation operates, input
limitation due to the antenna circuit varactor diode would operate. Therefore, we feel that the AGC operating
sequence employed is appropriate.
second gate control AGC loop) operate, the AGC system would become unstable and have an excessively large
influence on the transient response. Therefore the following structure cannot be used.
MOSFET second gate control → antenna damping → MOSFET second gate control
The AGC operating conditions are the same as those for the LA1175M.
Input impedance : 330Ω
Output impedance : 330Ω
Gain :
(attenuation) 20dB
25dB
(attenuation) dB
LA1193M, 1193V
No.4715-12/22