SI4133W-BM Silicon Laboratories Inc, SI4133W-BM Datasheet - Page 19

• Manufacturer Part Number: SI4133W-BM
• Description: IC SYNTHESIZER RF DUALBAND 28MLP
• Manufacturer: Silicon Laboratories Inc
• Type: Frequency Synthesizerr

Specifications of SI4133W-BM

• Pll: Yes
• Input: Clock
• Output: Clock
• Number Of Circuits: 1
• Ratio - Input:output: 1:2
• Differential - Input:output: No/No
• Frequency - Max: 2.6GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Frequency-max: 2.6GHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 336-1115

RF and IF Outputs (RFOUT and IFOUT)
The RFOUT and IFOUT pins are driven by amplifiers
that buffer the RF VCOs and IF VCO, respectively. The
RF output amplifier receives its input from either the
RF1 or RF2 VCO, depending upon which R- or N-
Divider register was last written. For example,
programming
automatically selects the RF1 VCO output.
Figure 13 on page 15 shows an application diagram for
the Si4133W. The RF output signal must be coupled to
its load through an ac coupling capacitor. An external
inductance between the RFOUT pin and the ac coupling
capacitor is required as part of an output matching
network to maximize power delivered to the load. This
2 nH inductance may be realized with a PC board trace.
The network is made to provide an adequate match to
an external 50 Ω load for both the RF1 and RF2
frequency bands. The matching network also filters the
output signal to reduce harmonic distortion.
The IFOUT pin must also be coupled to its load through
an ac coupling capacitor. The IF output level is
dependent upon the load. Figure 17 displays the output
level versus load resistance for a variety of output
frequencies. For resistive loads greater than 500 Ω the
output level saturates and the bias currents in the IF
output amplifier are higher than they need to be. The
LPWR bit in the Main Configuration register (Register 0)
can be set to 1 to reduce the bias currents and therefore
reduce the power dissipated by the IF amplifier. For
loads less than 500 Ω, LPWR should be set to 0 to
maximize the output level.
For IF frequencies greater than 500 MHz, a matching
network is required in order to drive a 50 Ω load. See
Figure 15.
IFOUT
Figure 15. IF Frequencies > 500 MHz
the
L
MATCH
N-Divider
>500 pF
register
for
50
Ω
RF1
Rev. 1.1
For frequencies less than 500 MHz, the IF output buffer
can directly drive a 200 Ω resistive load or higher. For
resistive loads greater than 500 Ω (f < 500 MHz) the
LPWR bit can be set to reduce the power consumed by
the IF output buffer. See Figure 16.
Reference Frequency Amplifier
The Si4133W provides a reference frequency amplifier.
If the driving signal has CMOS levels, it can be
connected directly to the XIN pin. Otherwise, the
reference frequency signal should be ac coupled to the
XIN pin through a 560 pF capacitor.
Power Down Modes
Table 10 summarizes the power down functionality. The
Si4133W can be powered down by taking the PWDNB pin
low or by setting bits in the Powerdown register
(Register 2). When the PWDNB pin is low, the Si4133W
450
400
350
300
250
200
150
100
50
0
0
Frequency
500–600 MHz
600–800 MHz
800–1 GHz
Figure 17. IF Output Voltage vs. Load
Figure 16. IF Frequencies < 500 MHz
LPWR=0
IFOUT
200
Table 9. L
400
Load Resistance (Ω)
>500 pF
MATCH
LPWR=1
600
Values
L
Si4133W
40 nH
27 nH
18 nH
800
MATCH
>200
Ω
1000
1200
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