SI4200-GM Silicon Laboratories Inc, SI4200-GM Datasheet - Page 20

• Manufacturer Part Number: SI4200-GM
• Description: IC TXRX TRI-BAND 32MLP
• Manufacturer: Silicon Laboratories Inc

Specifications of SI4200-GM

• Frequency: 850MHz, 900MHz, 1.8GHz
• Modulation Or Protocol: GSM
• Applications: Cellular, GSM Cellular Radio
• Voltage - Supply: 2.7 V ~ 3.3 V
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Operating Temperature: -
• Sensitivity: -
• Memory Size: -
• Data Rate - Maximum: -
• Current - Transmitting: -
• Current - Receiving: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

Aero+
Transmit Section
The transmit (TX) section consists of an I/Q baseband
upconverter, an offset phase-locked loop (OPLL), and
two output buffers that can drive external power
amplifiers (PA): one for the GSM 850 (824 to 849 MHz)
and E-GSM 900 (880 to 915 MHz) bands and one for
the DCS 1800 (1710 to 1785 MHz) and PCS 1900
(1850 to 1910 MHz) bands. The OPLL requires no
external filtering to attenuate transmitter noise or
spurious signals in the receive band, saving both cost
and power. Additionally, the output of the transmit VCO
(TXVCO) is a constant-envelope signal that reduces the
problem of spectral spreading caused by non-linearity in
the PA.
A quadrature mixer upconverts the differential in-phase
(TXIP, TXIN) and quadrature (TXQP, TXQN) signals
with the IFLO to generate a SSB IF signal that is filtered
and used as the reference input to the OPLL. The
Si4134T generates the IFLO frequency between 766
and 896 MHz. The IFLO is divided by two to generate
the quadrature LO signals for the quadrature modulator,
resulting in an IF between 383 and 448 MHz. For the E-
GSM 900 band, two different IFLO frequencies are
required for spur management. Therefore, the IF PLL
must be programmed per channel in the E-GSM 900
band. The IFLO frequencies are defined in Table 6 on
page 12.
The OPLL consists of a feedback mixer, a phase
detector, a loop filter, and a fully integrated TXVCO. The
TXVCO is centered between the DCS 1800 and
PCS 1900 bands, and its output is divided by two for the
GSM 850 and E-GSM 900 bands. The Si4134T
generates the RFLO frequency between 1272 and
1483 MHz. To allow a single VCO to be used for the
20
DCS/PCS
GSM
PA
PA
REG
TXBAND[1:0]
÷1, 2
Figure 13. Transmitter Block Diagram
REG
PLL
RF
Rev. 1.2
N
PDRB
DET
RFLO, high-side injection is used for the GSM 850 and
E-GSM 900 bands, and low-side injection is used for
the DCS 1800 and PCS 1900 bands. The I and Q
signals are automatically swapped within the Si4200
when switching bands. Additionally, the SWAP bit in
register 03h can be used to manually exchange the I
and Q signals.
Low-pass filters before the OPLL phase detector reduce
the harmonic content of the quadrature modulator and
feedback mixer outputs. The cutoff frequency of the
filters is programmable with the FIF[3:0] bits in
register 04h and should be set to the recommended
settings detailed in the register description.
RF2
φ
[15:0]
FIF[3:0]
N
IF
[15:0]
PDIB
Si4134T
PLL
÷2
IF
BBG[1:0]
Si4200
SWAP
Q
I