Nokia NHM-7 series, Руководство по обслуживанию

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NHM–7
System Module & UI
PAMS Technical Documentation
Page 29
Issue 1 10/2001
Nokia Corporation
RF Module
This RF module takes care of all RF functions of the engine. RF circuitry
is located on one side (B–side) of the PCB.
EMC leakage is prevented by using a metal B–shield, which screens the
whole RF side (included FM radio) of the engine. The conductive (silicon
or metal) gasket is used between the PCB and the shield. The metal
B–shield is separated to three blocks. The first one include the FM radio.
The second block include the PA, antenna switch, LNAs and dual RX
SAW. The last, but not least, block include the Hagar RF IC, VCO,
VCTCXO, baluns and balanced filters. The blocks are divided on the ba-
sis that the attenuation between harmonics of the transmitter and the
VCO signal (including Hagar IC) is a high (over 100dB). The VCO and TX
outputs of the Hagar RF IC are located one another as far as possible. In
order to guard against the radiated spurious inside blocks, the RF trans-
mission lines are made with striplines after PA.
The baseband circuitry is located on the A–side of the board, which is
shielded with a metallized frame and ground plane of the UI–board.
Maximum height inside on B–side is 1.8 mm. Heat generated by the cir-
cuitry will be conducted out via the PCB ground planes and metallic
B–shield
RF Frequency Plan
HAGAR
PLL
26 MHz
VCTCXO
f
f/2 f/4
f
3420–
3840
MHz
925–960
MHz
880–915
MHz
I–signal
1805–1880
MHz
f
f/4
f
f/2
Q–signal
I–signal I–signal I–signal
RX
TX
I–signal
Q–signal
1710–1785
MHz