S7-PRO Maintenance Manual (Basic Version V2.1)
INTERNAL
2012-07-20
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Page 66 of 97
As shown in the block diagram, the transmitter includes high frequency, intermediate
frequency, and low frequency channels. The IQ signal is transmitted to the built-in power
amplifier through the up-converter. The AGC is used to control the power output, and the
AGC circuit includes a power detector to achieve a transmit power control range greater than
85 dB. The output radio frequency signal is sent to the front-end module, and transmitted by
the antenna to QTR8615. After the signal is amplified in the internal LNA, it is
down-converted to I/Q baseband signal.
The device supports WCDMA that uses the frequency band of 5 MHz and GSM that uses the
frequency band of 4 MHz.
Figure 9-5
Diagram of circuits of the RF antenna switch
The red part indicates that the signal is transmitted into the antenna switch (U46) through the
transmit channel, and the blue part indicates that the signal is transmitted out of U46 through
the receive channel.
Figure 9-6
Diagram of circuits of WCDMA2100 RF channels
The red part indicates the transmit channel, and the blue part indicates the receive channel.
Both the transmit channel and the receive channel are connected to the antenna switch
through the duplexer (U20).
