V.120C Rf Circuit - Motorola Tarpon V. 120C Service Manual

V.120c
connector-keypad, compression type
32 Khz crystal controlled by CCAP IC for RTC and slotted
mode operation.
The charging circuit consists of Fast charger which is similar to
StarTac , V.120c phones will also support Mid Rate charger
The flex connector interfaces the main board with the Display,
Speaker and the RTC Battery in the flip.
The accessory antenna port is present on the back side of the
phone near the antenna.
All the logic parts and IC's are placed on one side and all RF
parts and IC's are placed on another side of the PCB

V.120c RF CIRCUIT

The RF circuit is somewhat similar to Dual band Caliber/Shark
product, the V.120c phone contains FE IC (the front end IC)
The receiver contains two complete receiver paths : 800 Mhz
path that is used by 800 Mhz analog and 800 Mhz CDMA
signals, and a PCS band(1900 Mhz) path for PCS signal. The
two paths have different RF, LO and IF frequencies.
The switching of the antenna and accessory antenna port is
mechanical, normally close circuit with antenna connector, but
when accessory RF cable is inserted in the accessory port the
switch opens the circuit with antenna and closes the circuit with
the accessory port.
For Frequencies and channel numbers look at the table in this
manual
The FE IC contains the LNA's , interstage filtering and Mixers,
the switching and gain of the LNA's is controlled by the
control signals
ZIF/SYN IC extracts the broadband signal from the IF ,
demodulate the analog signal and sends it to the audio logic
side for further processing.
ZIF/SYN IC controls the Main VCO ,the second LO and the
TX offset VCO (in analog mode).
V.120c uses the single VCO module for main
LO (one for the 800 mhz band and another for PCS band) The
output is split into RX_LO and TX_LO
for both the bands.
V.120c uses the ME3 IC - the mixer exciter IC
The ME3 IC allows to control the RF output power. The ME3
IC requires two LO's, one for PCS, and the other for the 800
Mhz band.
The IF pins (input to the ME3 IC) are the same for any band.
The control signal (TX Att) at the AGC pins control the gain of
the ME3 IC.
There is an external interstage RF filter between the mixer and
exciter.
Balun is a component external to ME3 IC and is not a discreet
part as in V.60c
From the mixer the outputs take two different paths one for TX
PCS band and another for TX 800 Mhz band.
ME3 IC has 50 dBM attenuator control (input IF level= -
23dBM , max output TX level= 25dBM)
At the output of ME3 IC band filter are used , in the PCS path
two split band filters are used. V.120c uses celeritekPA HBT
and not MOSFET as in V.60c.
Two stage PA in 800 Mhz band and three stage PA in PCS
band .
In V.120c PA adjustable bias only Drain therefore the output
power can be controlled by PA_B+ DAC besides ME3 IC
(through Tx_Attn). PA gate Bias is not adjustable but fixed and
regulated at 2.95v.
© 2001 Motorola, Inc.
Product Description
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