Huawei ETS2000 Series Maintenance Manual page 22

SAW filter to experience the frequency mixing operation. Since RFR6120 assumes
the "Zero Intermediate Frequency" structure, the radio frequency signal can be
directly converted into baseband signals. The following operations are I/Q
demodulation and filter amplifying, and ADC processing. Finally, the digital
baseband signal will be sent to baseband processing unit MSM6000.
See Figure 1-25 for the receiving unit:
LNA
Duplexer
RFR6120 internal components
2. Transmit unit:
Primary unit function: Emission modulation module RFT6120 directly amplifies
analog I/O signals after DA conversion. Next, radio frequency signals are generated
after RF Mixer and RF filter function on the signals. Then the RF signals are
amplified by the RF amplifier, so that RF emission signals set with certain output
power value are generated. Finally, after the duplex module sufficiently filters
out-of-band spurious emission signals, the signals will be sent to the antenna. The
other function of the duplex module is to prevent the emission signals from
disturbing the work of the receiver. See Figure 1-26 for the emission unit.
SAW
87731
Figure1-24
Radio frequency receiving unit
22
Mixer
LPF
LO
demodulator
AGC
MSM
6000