SI4133T-GM Silicon Laboratories Inc, SI4133T-GM Datasheet - Page 21

• Manufacturer Part Number: SI4133T-GM
• Description: IC RF SYNTHESIZER DUAL 28MLP
• Manufacturer: Silicon Laboratories Inc
• Type: Frequency Synthesizerr

Specifications of SI4133T-GM

• Pll: Yes
• Input: Clock
• Output: Clock
• Number Of Circuits: 1
• Ratio - Input:output: 1:2
• Differential - Input:output: No/No
• Frequency - Max: 1.8GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Frequency-max: 1.8GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.2. 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 which 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 which is
filtered and used as the reference input to the OPLL.
The Si4133T 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
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 7 on page 15.
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 Si4133T
generates the RFLO frequency between 1272 and
1483 MHz. To allow a single VCO to be used for the
the
GSM
DCS
PCS
E-GSM 900
PA
PA
band,
REG
TXBAND[1:0]
two
Figure 14. Transmitter Block Diagram
÷1, 2
different
REG
IFLO
PLL
RF
Rev. 1.4
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.
N
PDRB
DET
RF2
φ
[15:0]
FIF[3:0]
N
IF
[15:0]
PDIB
Si4133T
PLL
÷2
IF
Si4200
BBG[1:0]
SWAP
Q
I
Aero
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