LA1136NM datasheet(13/28 Pages) SANYO

13 / 28 page

(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.

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 QO of 70 to 80, the QL was 20 to 30. The detector input impedances of the LA1136N and

LA1137N are higher. This means that the QO and QL of the tank coil are approximately the same. A coil with a QO of

approximately 30 is recommended.

Recommended Coil Specifications

(1) RF alignment coil

Parasitic oscillations in the 50 to

100 MHz region

Required local

oscillator signal

Primary coil

Secondary coil

LA1136N, 1136NM, 1137N, 1137NM

No. 3507-13/28

LA1136NM データシート(PDF) 13 Page - Sanyo Semicon Device