SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R08
Objective Specification
System description
Page 12 of 188
1.2.1
Internal blocks
SARA-G3 and SARA-U2 series modules internally consist of the RF, Baseband and Power Management sections
here described with more details than the simplified block diagrams of Figure 1, Figure 2, Figure 3 and Figure 4.
RF section
The RF section is composed of the following main elements:
2G / 3G RF transceiver performing modulation, up-conversion of the baseband I/Q signals, down-conversion
and demodulation of the RF received signals. The RF transceiver includes:
Constant gain direct conversion receiver with integrated LNAs
Highly linear RF quadrature GMSK demodulator
Digital Sigma-Delta transmitter GMSK modulator
Fractional-N Sigma-Delta RF synthesizer
3.8 GHz VCO
Digital controlled crystal oscillator
2G / 3G Power Amplifier, which amplifies the signals modulated by the RF transceiver
RF switch, which connects the antenna input/output pin (
ANT
) of the module to the suitable RX/TX path
RX diplexer SAW (band pass) filters
26 MHz crystal, connected to the digital controlled crystal oscillator to perform the clock reference in
active-mode or connected-mode
Baseband and Power Management section
The Baseband and Power Management section is composed of the following main elements:
Baseband processor, a mixed signal ASIC which integrates:
Microprocessor for controller functions
DSP core for 2G / 3G Layer 1 and audio processing
Dedicated peripheral blocks for parallel control of the digital interfaces
Audio analog front-end
Memory system in a multi-chip package integrating two devices:
NOR flash non-volatile memory
RAM volatile memory
Voltage regulators to derive all the system supply voltages from the module supply
VCC
Circuit for the RTC clock reference in low power idle-mode:
SARA-G340, SARA-G350 and SARA-U2 series modules are equipped with an internal 32.768 kHz crystal
connected to the oscillator of the RTC (Real Time Clock) block that gives the RTC clock reference needed
to provide the RTC functions as well as to reach the very low power idle-mode (with power saving
configuration enabled by the AT+UPSV command).
SARA-G300 and SARA-G310 modules are not equipped with an internal 32.768 kHz crystal: a proper
32 kHz signal must be provided at the
EXT32K
input pin of the modules to give the RTC clock reference
and to provide the RTC functions as well as to reach the very low power idle-mode (with power saving
configuration enabled by AT+UPSV). The
32K_OUT
output pin of SARA-G300 and SARA-G310 provides
a 32 kHz reference signal suitable only to feed the
EXT32K
input pin, furnishes the reference clock for
the RTC, and allows low power idle-mode and RTC functions support with modules switched on.
