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1-12 (No.RA070<Rev.001>)
2.3.3 Receiver System
2.3.3.1
RF Circuit
The receive signal from ANT SW (D201, D202, D203 and D207) passes through the high-pass filter (L302, L307, L308, L312, L314
and L315) to remove unwanted signals and amplified by a RF amplifier (incorporated in Transceiver IC (IC303)). The signal is then
fed to the mixer (incorporated in Transceiver IC (IC303)) and converted to the baseband signal.
2.3.3.2
Baseband Circuit
The baseband signal is then be fed into an ADC (incorporated in Transceiver IC (IC303)), generates the I and Q data. This data is in
the form of Serial Interface, and sent to the MPU/DSP (IC401).
Fig.2 RF and Baseband circuit
2.3.3.3
Audio Amplifier Circuit
Audio processing (high-pass filter, low-pass filter, de-emphasized and so on) at Analog FM mode and decoding at Digital mode are
processed by DSP. I2S signal from DSP is converted to audio signal at CODEC (IC601). The signal goes to internal speaker or
universal connector for external speaker through the internal Class D amplifier.
Audio path inside the Codec is controlled by I2C.
Fig.3 Audio amplifier circuit
ANT
ANT
LPF SW
D202
D203
D207
D201
ANT
L302
L307
L308
HPF
IC303
L312,
L314, L315
HPF
RFAMP
MIXER
PLL
VCO
ADC
Serial
I/F
IC401
MPU/DSP
LC
I/F
IC303
Transceiver IC
Serial
IC401
MPU/DSP
DSP
IC601
CODEC
DA
I2C
I2S
Class D
Filter
External Speaker
Internal Speaker
LC
Class D
Filter