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As the figure shows: downlink from base station to mobile phone leaded into receiver circuit by antenna.
The receiver circuit mainly contains Antenna, RF-Connector(CN600), RF-Switch(FE600), Transceiver(U602),
DBB(U201) and ABB(U202) etc.
W420 use inter antenna. The antenna is paste on back cover of the mobile phone in the antenna area
through glue on back of antenna. After main board’s assemble, feed point of antenna must be pressed well
with input of antenna on main board. Signal intension rest with connecting between antenna and main board,
so make sure of the two contacts well
CN600 is test jack match with factory when calibrating RF. The switching inside is mechanical, break up
when the test probe insert, signal input to mobile phone or output from mobile phone through probe. After
probe exiting, switching close up, signal output from antenna. The max impedance of CN600 is 50 ohm, max
insert loss is 0.1dB
FE600 is a RD-switch controlled by DBB(U200), its working band is GSM, DCS and PCS, structure as
follows:
DDB(U201) set voltage for V_TX_LOW and V_TX_HIGH which is two control unit of FE600 through
external gate circuit Q600_A and Q601_A indirect. Control signal TSPACT01 and TSPACT02 from U200
control if set high to V_TX_lOW and V_TX_HIGH for RF source through estate (connect/cut off) of Q600-A and
Q601-A. Then realize to control working estate of U101
Logic of control is as follows:
When the mobile working, high frequency signals are divided into two paths balanceable output by FE600
after received by antenna. These two paths of signals input U602 from pin LNAGSMP and LNAGSMN (or
LNADCSP and LNADCSN or LNAPCSP and LNAPCSN) respective. First, do low noise magnify, after magnify
Summary of Contents for W420
Page 1: ...Voxtel Repair Manual Item W420 ...
Page 23: ...23 3 LDO circuit ...
