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LEON-G100/G200 - System Integration Manual

GSM.G1-HW-09002-C Preliminary System description

Page 31 of 75

1.7 RF connection

The core of the RF part of the LEON-G100/G200 modules is the transceiver integrated in the GSM/GPRS single

chip. The integrated receiver covers the four GSM bands GSM850 MHz, EGSM900 MHz, DCS1800 MHz and

PCS1900 MHz, using two LNAs integrated in the RF Transceiver and providing quad-band operation. In the first

duplexer the two low bands (RX path 850 MHz and 900 MHz) are separated, filtered, and routed to a single

output and then connected to the LNA of the first low band receiver. In the same way the two high bands (RX

paths 1800 MHz and 1900 MHz) are connected to the second duplexer to LNA of the second high band

receiver.

Two different RF TX outputs are provided, one for 850/900 MHz bands and one for 1800/1900 MHz bands. The

quad-band front end module amplifies these signals maintaining two separate paths.

By default the RF I/O signal is routed through a 50 Ω antenna interface.

The temperature dependent performance of the oscillator and RF high power circuits are controlled by the

baseband with the aid of the NTC sensor.

1.8 Antenna supervisor

Antenna detection is internally performed by the module via ANT: the RF port is DC coupled to the ADC unit in

the baseband chip. The module measures the DC voltage at ANT, in the range of 0..2 V. Additionally, the

module can inject a known DC current (~ 100 µA) on ANT and measures the resulting DC voltage.

LEON-G100

LEON-G200

ANT

A-to-D

Converter

Current

Source

Choke

Blocking

RF Transceriver

Figure 18: Antenna Supervisor internal circuit

If the DC voltage is present on ANT, or a DC connection to a known resistor at the radiating element is

implemented, the module will be able to check the connection to the Antenna element.

Refer to the u-blox AT Commands Manual [2] for more details on how to access this feature.

1.9 Audio

LEON-G100/G200 modules provide four analog and one digital audio interfaces:

Two microphone inputs:

First microphone input: direct connection of an electret condenser microphone, used in the handset mode or

in the hands free mode

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