Egsm900 Tx Path Of Mjoelner Rf Asic - Nokia 616 Service Manual

TFE-4/RV-1
TF4 Technical Information

EGSM900 TX path of Mjoelner RF ASIC

The balanced TX signal is provided by the base band to the Mjoelner RF ASIC. The TX
paths of the Mjoelner RF ASIC include mainly two RF modulators for up-conversion of
the base band signals, one for EGSM900 and one for GSM1800. The base band signal is
modulated with the LO signal corresponding to the wanted TX channel. The GSM TX out-
put of the Mjoelner RF ASIC is a balanced signal.
At the output of the Mjoelner RFASIC the signal is fed to the EGSM TX SAW filter (Bal-
anced to single ended), a 3 dB pad, and the 900 MHz buffer to the PA EGSM input.
EGSM900 TX path of the Power Amplifier (PA)
The PA EGSM900 part has a maximum output power of app. 35 dBm. The EGSM900 out-
put is controlled by the power control loop. From the EGSM900 output of the PA the RF
signal is fed through the directional coupler (one of the power control loop components)
to the antenna switch.
Antenna Switch (TX/RX switch)
The antenna Switch works as a duplexer for the RX and TX signals. Additionally, it sup-
presses the EGSM900 TX harmonics generated by the PA. The antenna switch is con-
trolled by the Mjoelner RF ASIC using the control signals CONT1, CONT2 and CONT3. The
following table shows the possible different states.
CONT1
[Volt]
0
0
0
2.7
Page 8b-56
Company Confidential
CONT2 CONT3
EGSM Rx
[Volt] [Volt]
0 0
0 0
0 2.7
0 0
Copyright © 2005 Nokia Corporation.
Company Confidential
DCS Rx EGSM Tx
X
X
X
Nokia Customer Care
DCS/PCS
Tx
X
Issue 2.0 Mar/2005