Transmitter Path - Motorola MTP700 Detailed Service Manual

TRANSCEIVER 800 MHz

Transmitter Path

When the radio is transmitting (see Figure 4.2-3), the microphone audio is sent to the
GCAP3 (CODEC). The CODEC performs 13-bit analog-to-digital conversion and the dig-
ital signal is routed to the DSP (part of RedCap2). The DSP performs coding, Error Cor-
rection and modulation. From the DSP, the signal is sent to the WPIC.
From Tx PLL
WPIC LNODCT
REDCAP2
GCAP
Mic
In the WPIC, the digital baseband I & Q signals are converted into corresponding analog
signals. These signals are also filtered. From the WPIC, I & Q signals are injected to the
LNODCT. In the LNODCT the data is mixed with RF signal.
From the differential output of the LNODCT the modulated RF signal is injected to the
Balun-Filter, that transforms the differential input into single output, and then it is routed to
the antenna via the Antenna Switch.
The feedback signal is used for power control.
MTP700 Portable Radio / Detailed Service Manual
-3dB
0dB
Balun-Filter Attenuator
-6dB
Attenuator
Figure 3 Transmit Path Block Diagram
Figure 4.2-3 Transmit Path - Block Diagram
32dB
RF PA
-0.8dB
-0.2dB
Antenna
Switch
Power at Antenna:30dBm + 2dB
4.2 - 7
Harmonic
Filter