SI4133T-BM Silicon Laboratories Inc, SI4133T-BM Datasheet - Page 23

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

Specifications of SI4133T-BM

• 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: Contains lead / RoHS non-compliant

4.4. VCO Inductor Design
4.4.1. Determining L
The center frequencies for the RF1, RF2, and IF VCOs
in the Si4133T are set using an external inductance
(L
designed to ensure maximum manufacturing margin for
the desired VCO frequency tuning ranges. Because the
total tank inductance is in the low nH range, the
inductance of the package (L
determining the correct external inductance.
Figure 16 shows the detailed configuration of the
integrated VCOs. The total inductance (L
VCO is the sum of the external inductance (L
the package inductance (L
(C
capacitance (C
(C
capacitance (C
C
values are defined in Table 7.
The center frequency is calculated as follows:
The value for the external inductor is determined by:
where f
TUNE
EXT
TOT
VAR
). It is very important that L
) of each VCO is the sum of the self tuning
), and the fixed capacitance (C
and C
C
L
L
CEN
PKG
EXT
NOM
f
VAR
CEN
L
= desired center frequency of VCO
= nominal capacitance from Table 7.
= package inductance from Table 7.
= external inductance required
EXT
NOM
TUNE
at their center values. C
=
=
) of each VCO is calculated with
------------------------------------------------------------------ -
2π C
PLL
), the PLL varactor capacitance
------------------------------------------- - L
(
EXT
2πf
CEN
NOM
PKG
1
PKG
)
2
(
C
L
C
). The total capacitance
1
PKG
NOM
VAR
) must be considered in
TUNE
SELF
+
–
L
FIX
EXT
Figure 16. VCO Block Diagram
EXT
PKG
). The nominal
NOM
)
TOT
be properly
C
TUNE
) of each
and L
EXT
) and
PKG
Rev. 1.4
For example, the RF1 VCO for a triple-band design
requires f
C
The above equation shows L
connected between the RFLA and RFLB pins.
Please see “AN49: Aero Transceiver PCB Layout
Guidelines” for details on how to implement and verify
the proper value of L
C
Supported Bands
European Dual-Band (900/1800)
Triple-Band (900/1800/1900)
Quad-Band (850/900/1800/1900)
or North American Dual Band
(850/1900)
Supported Bands
European Dual-Band (900/1800)
Triple-Band (900/1800/1900)
Quad-Band (850/900/1800/1900)
or North American Dual Band
(850/1900)
NOM
FIX
= 4.3 pF and L
AMP
Table 8. VCO f
CEN
Table 9. VCO L
IC
= 1897 MHz. Table 7 on page 15 shows
PACKAGE
L
L
EXT
Si4133T
PKG
PKG
PKG
/2
/2
.
CEN
= 1.5 nH for the RF1 VCO.
EXT
EXT
BOARD
Values (MHz)
L
Values (nH)
EXT
= 0.14 nH should be
VCO
1862 1341 782
1897 1381 810
1864 1378 831
VCO
0.20 1.43 4.77
0.14 1.27 4.34
0.20 1.28 4.04
RF1
RF1
VCO
VCO
RF2
RF2
Aero
VCO
VCO
IF
IF
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