Service Manual

1.3.5 Output power : 300 mW
2. OPERATING INSTRUCTION
Before the card can be used to access the internet or sending/receiving e-mails etc., installation of software for the 1900-1X-CDMA card
needs to be performed as per the instructions that accompany the installation diskette/CD. When the card is installed and configured
properly, it will be automatically recognized when inserted in the type II slot in a Laptop computer. The data can be accessed by clicking
On the self explanatory icons in the 1900-1X-CDMA driver software.
3. CIRCUIT INSTRUCTION
1900-1X-CDMA is designed based on the CDMA standard, EIA/TIA and consisted of RF and logic assembly part.
3.1 RF part
RF part consists of power supply, frequency synthesizer, TX and RX sections.
3.1.1 Power supply
Power for RF section is supplied from laptop battery. Following voltages are generated by the on-board power management IC: ;
 3.0V  RX IF part
 3.0V  TX RF part
 3.0V  PLL
 3.0V  TCXO
 3.0V  IFT, IFR, Baseband circuitry
 3.0V  PA_REF
 2.8V  PCMCIA interface circuitry
3.1.2 Frequency synthesizer
Frequency synthesizer uses VC_TCXO (19.68 MHz) as a reference frequency. Then 19.68MHz of VC_TCXO is divided by the reference
divider to 10KHz comparison frequency. The internal RF VCO generates the LO frequencies for both TX/RX bands and receive IF. The DC
control voltage for TCXO is generated by low pass filtering a PDM waveform provided by MSM-5500 baseband IC. The synthesizer employs
a digital phase locked loop (PLL) technique. Combined with a high quality reference OSC, it provides a very stable local oscillator (LO) in
the range of 1720 ~ 1780 MHz and 420.76 MHz for receive IF local oscillator.
3.1.2.2 Rx IF synthesizer (420.76 MHz)
Rx IF synthesizer oscillates at 420.76 MHz that is the double of Rx IF frequency. The IF frequency 210.38 MHz is generated inside the IFR
chip by dividing this frequency by 2.
3.1.2.3 Tx IF synthesizer ( 260.76MHz )
TX PLL consists of PLL synthesizer, IFT3000, Loop filter and the VC_TCXO. It oscillates at 260.76MHz that is double the
the TX IF frequency. The 130.38MHz TX IF frequency is generated by dividing this by 2 inside the IFT
3.1.3 Rx part
Rx parts consist of Agilent FBAR duplexer, Receiver front end chip (LNA, down converter), IF SAW and IFR3000 and the role of each part is
as follows;
3.1.3.1 Duplxer
Agilent FBAR Duplexer consists of TX and RX filters TX filter consists of BPF (Band Pass Filter) and rejects any TX spurs or noise falling into
the RX band. The RX port has a BPF that prevents TX interference into the RX band.
3.1.3.2 RF F/E MD59-0049 LNA/DOWNCONVERTER
MD-59-0049 front end chip consists of an LNA, RF amplifier, Mixer, IF amplifier, and LO Buffer. This IC has good linearity, wide dynamic
range, and low power consumption.
The down converter generates RF_IF of 210.38 using the PLLMHz which is fed in to the IF-Baseband chip (IFR-3000).
3.1.3.3 IFR3000
IFR3000 is located between MSM-5000 digital processor and RF subsystem. It controls the RX power level with an internal AGC (Automatic
Gain Control) amplifier, depending on the IF signal strength. It has 90dB of dynamic range. The full dynamic range is from +45dB to –45
dB at gain control voltage of 2.8 to 0.1 volts respectively. The IF mixer down-converts RX-IF signal (210.38 MHz) to quadrature analog
basedband.
IFR-3000 CDMA receive signal path includes;
IF to Baseband Down Conversion
Separate Filters and ADCs
Conversion of analog base-band to digital format