Philips 32PW9618 Service Manual page 144

EN 144 9.
ANTENNA
1750
1 RT-01T
0001
Hole 3.5 mm
1
2
F748
F748
5613
F704
3n3
2630
F704
39p
BAV99
6602
F703
F703
Figure 9-21 Antenna input circuit
LNA
5614
8n2
2603 2641
33p 12p
The LNA is a cascode configuration around transistor 7601.
This circuit provides gain with a low noise figure, while
providing isolation from the oscillator to antenna. This isolation
is necessary to comply with the legal requirements for radiated
interference.
The output of the LNA and the LO signal is mixed in transistor
7602. This is a one transistor mixer that provides high
conversion gain with low LO input signal. This level is only
around 20 mV. The reason for this high conversion gain is that
there is a 10.7 MHz trap at the base (5605 - 2610).
The output of the mixer is a tuned circuit at 10.7 MHz. The coil
is pre-aligned at the factory.
EM6E
Circuit Descriptions, Abbreviation List, and IC Data Sheets
2652
2
I O
1
33p
3 IGND OGND
4
GND GND1
1602 B3589
864M
CL36532008_080.eps
+8V
2607
3612
47R
1p5
7601
2602
BFC520
Figure 9-22 LNA and mixer circuit
LNA and Mixer
6
5
7
8
130503
+8V
F710
F710
7602
BFR92A
MIXER
10.7 MHz
5615
3 4
2
1 6
IF
CL36532008_081.eps
130503