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2.3.3
Receiver Path
The receiver section in the radio is based on the DCR (Direct Conversion) technology. The main
concept of this technology is down converting of the RF signal directly into a base band signal,
skipping the intermediate stage of IF signal.
The receiver path includes the following items.
•
Diplexer
•
Antenna Switch
•
RF Switch (for bypass control)
•
Off Channel Detector and Inverting Schmitt Trigger
•
Balanced-Unbalanced Converter (BALUN)
•
Limiter Diodes with Pre-selector Filters
•
LNA Module
•
2-bit 6/12/18 dB Step Attenuator
•
Discrete Front Filter
•
RF Coupler
•
Tunable Post-selector Filter (350 MHz)
•
Saw Filter (800 MHz) Off Channel Detector
•
Comparator
•
Low Noise Amplifier (LNA) integrated with Step Attenuator and Automatic Gain Control (AGC)
continuous attenuation
•
RFIC for mixing
•
Baseband filtering and internal 55 dB AGC continuous attenuation (inclusive of the internal 10 dB
step attenuator) which consists of all the baseband receive chain and mixer.
2.3.4
Frequency Generating Section
The frequency generating section includes the following components.
•
Low Band VCO (350–410 MHz)
•
High Band VCO (410–470 MHz)
•
RFIC Fractional-N Synthesizer
•
Reference Oscillator
•
Loop Filter
•
Voltage Multiplier
2.4
Global Positioning System, Bluetooth, and Global Navigation
Satellite System Section
The GPS/BT is provided by a single chip solution in 65-nm CMOS process that integrates GPS and
Bluetooth functions. The GNSS is a concurrent GNSS (GPS, GLONASS, and BeiDou) positioning chip.
The GPS/BT and GNSS section includes the following main components:
MN002465A01-AN
Chapter 2 : Overview
29
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