MOTOROLA CONFIDENTIAL - PROPRIETARY
10
November 20, 2000
6881036B20
Circuit Description
Product Family 38C
is amplified through tuned transistor amplifier
Q252
before being used to mix with
the received frequencies through the emitters of the dual mixer transistor
Q450
.
The mixer produces sum and difference signals consisting of RX frequency
plus
RX
VCO frequency and RX frequency
minus
RX VCO frequency. The difference signal
is fed to SAW (surface acoustic wave) filter
FL457
. The purpose of the SAW filter
is to provide comprehensive removal of harmonics created during the mixing
process.
The resulting 400 MHz IF signal is passed to isolation amplifier
Q480
. The isolation
amplifier couples the analog IF signal to the following circuit which has a different
ground and also protects the base-band signals from stray RF. The isolation
amplifier is supported by Magic IC
U200 Pin C7
SW_VCC.
The IF signal is then passed to the Magic IC
U200
Pin A7
PRE IN where it is
demodulated using external 800 MHz varactor diode
CR249
(RX local oscillator set
up), which is driven by from Magic IC
U200 Pin A9
LO2_CP.
The demodulated signal is converted internally to base-band digital form and
passed along the RX SPI bus to the Whitecap IC.
The RX SPI signal is made up of BDR (base-band data receive), BFSR (Base-band
Frame Synch Receive) and BCLKR (base-band clock receive), fed from Magic IC
Pin G8
,
Pin G9
, and
Pin F7
respectively.
The Whitecap IC
U800
receives these signals on
Pin A3
,
Pin D4
, and
Pin B4
.
Within the Whitecap IC the signal is digitally processed to reduce Baud rate and
remove error correction bits.
The resulting digital signal is fed down the DIG_AUD_SPI bus to the GCAP II
U900
,
where it is converted to analog form and distributed to the correct outputs:
The Alert is generated within the Whitecap IC, given the appropriate data from the
incoming signal or SMS, and is fed to the alert pads
LS1
. This signal is supported
by ALRT_VCC, which is generated from B+ through
Q903
.
For the headset only, the SPKR signal is used from GCAP II Pin
H6
. The output is
fed out to the headset jack
J504 Pin 3
.
Transmit
Analog voice is fed from the Aux Microphone attached to the headset and is routed
from
Pin 1
of the headset jack
J504
to GCAP II,
Pin H3
.
Within the GCAP II, the analog audio is converted to digital and clocked out onto
the DIG_AUD SPI bus to the Whitecap IC
U800
.
000714-O
Figure 2. IF Isolation Amplifier Operation
Isolation
Amp
MAGIC
IC
U200
101001010100
Base-band
Signal
000714-O
Summary of Contents for 38C V100
Page 1: ...Level 3 Service Manual Model V100 GSM Technology Product Family 38C Personal Communicator ...
Page 2: ......
Page 73: ...V100 BOARD LAYOUT PAGE 1 2 ...
Page 74: ...V100 BOARD LAYOUT PAGE 2 2 ...
Page 77: ...V100 CONNECTOR SCHEMATICS ...
Page 78: ...V100 DISPLAY SCHEMATICS ...
Page 79: ...V100 FM SCHEMATICS ...
Page 81: ......
Page 83: ......