LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 10 of 183
C1-Public
•
Power management unit with integrated DC/DC converter for the power amplifier module
•
Voltage-controlled temperature compensated 26 MHz crystal oscillator (VC-TCXO)
While operating in 3G mode, the RF transceiver performs direct up-conversion and down-conversion
of the baseband I/Q signals, with the RF voltage controlled gain amplifier being used to set the uplink
TX power. In the downlink path, the integrated LNA enhances the RX sensitivity while discrete inter-
stage SAW filters additionally improve the rejection of out-of-band blockers. An internal
programmable gain amplifier optimizes the signal levels before delivering to the analog I/Q to
baseband for further digital processing.
For 2G operations, a constant gain direct conversion receiver with integrated LNAs and highly linear
RF quadrature demodulator are used to provide the same I/Q signals to the baseband as well. In
transmission mode, the up-conversion is implemented by means of a digital sigma-delta transmitter
or polar modulator depending on the modulation to be transmitted.
The RF antenna pad for the diversity receiver (
ANT_DIV
) available on LISA-U230 modules is directly
connected to the antenna switch for the diversity receiver, which dispatches the incoming RF signals
to the dedicated SAW filter bank for out-of-band rejection and then to the diversity receiver port of
the RF transceiver.
In all the modes, a fractional-N sigma-delta RF synthesizer and an on-chip 3.296-4.340 GHz voltage-
controlled oscillator are used to generate the local oscillator signal. The frequency reference to RF
oscillators is provided by the 26 MHz VC-TCXO. The same signal is buffered to the baseband as a host
reference for clock generation circuits while operating in active mode.
LISA-U2 series modulation techniques
Modulation techniques related to radio technologies supported by LISA-U2 modules, are listed as
follows:
•
GSM
→
GMSK
•
GPRS
→
GMSK
•
EDGE
→
GMSK / 8-PSK
•
WCDMA
→
QPSK
•
HSDPA
→
QPSK / 16-QAM
•
HSUPA
→
QPSK / 16-QAM
LISA-U2 series Baseband and Power Management Unit section
Another shielding box of
the
LISA-U2 modules includes all the digital circuitry and the power supplies,
basically the following functional blocks:
•
Cellular baseband processor, a mixed signal ASIC which integrates:
o
Microprocessor for controller functions, 2G & 3G upper layer software
o
DSP core for 2G Layer 1 and audio processing
o
3G coprocessor and HW accelerator for 3G layer 1 control software and routines
o
Dedicated HW for interfaces management
•
Memory system in a Multi-Chip Package (MCP) integrating two devices:
o
NOR flash non-volatile memory
o
DDR SRAM volatile memory
•
Power Management Unit (PMU), used to derive all the system supply voltages from the module
supply VCC
•
32.768 kHz crystal, connected to the Real Time Clock (RTC) oscillator to provide the clock
reference in idle or power-off modes
