LA1136N Datasheet, PDF (13/28 Pages) Sanyo Semicon Device – AM Tuners for Car Radios and Home Stereos

LA1136N, 1136NM, 1137N, 1137NM
(2) Oscillator coil
The oscillator for LA1136N and LA1137N can operate up to 100 MHz. Stray capacitance resulting from poor oscillator coil
design can cause antiresonance in the range 50 to 100 MHz. This results inparasitic oscillations at the local-oscillator buffer
output, which can prevent the PLL from locking.
Parasitic oscillations in the 50 to
100 MHz region
Required local
oscillator signal
Countermeasure
1 Reduce the oscillator coil stray capacitance (tapping is recommended)
2 Connect a capacitor of 43 pF or greater between OSC BUFF (Pin 24 for LA1136N, and Pin 20 for LA1137N) and GND.
(3) IF tank coil
LA1136N Pin 13 load coil
LA1137N Pin 10 load coil
The IF tank coil connected to IF OUT has different specifications to that of the LA1135. The detector input impedance of the
LA1135 is low, therefore for a Q_O of 70 to 80, the Q_L was 20 to 30. The detector input impedances of the LA1136N and
LA1137N are higher. This means that the Q_O and Q_L of the tank coil are approximately the same. A coil with a Q_O of
approximately 30 is recommended.
4. Recommended Coil Specifications
(1) RF alignment coil
Primary coil
Secondary coil
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