LTC6945 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC6945' PDF : 28 Pages View PDF
LTC6945
APPLICATIONS INFORMATION
and Johanson Technology, can be attractive alternatives.
See Table 13 for recommended balun part numbers versus
frequency range.
The listed SMT baluns contain internal chokes to bias RF±
and also provide input-to-output DC isolation. The pin
denoted as GND or DC FEED should be connected to the
VRF+ voltage. Figure 20 shows a surface mount balun’s
connections with a DC FEED pin.
Table 13. Suggested Baluns
fRF (MHz) PART NUMBER MANUFACTURER
TYPE
350 to 900 #617DB-1673
TOKO
TL
400 to 600 HHM1589B1
TDK
SMT
600 to 1400 BD0810J50200
Anaren
SMT
600 to 3000 MABACT0065
M/A-COM
TL
1000 to 2000 HHM1518A3
TDK
SMT
1400 to 2000 HHM1541E1
TDK
SMT
1900 to 2300 2450BL15B100E Johanson
SMT
2000 to 2700
HHM1526
TDK
SMT
3700 to 5100 HHM1583B1
TDK
SMT
4000 to 6000 HHM1570B1
TDK
SMT
VRF+
RF+ 12
LTC6945
RF– 11
321
TO 50Ω
LOAD
BALUN
4
5
6
6945 F20
The listed TL baluns do not provide input-to-output DC
isolation and must be AC coupled at the output. Figure 21
displays RF± connections using these baluns.
VRF+
RF+ 12
LTC6945
RF– 11
SEC
TO 50Ω
LOAD
PRI
6945 F21
Figure 21. Example of a TL Balun Connection
SUPPLY BYPASSING AND PCB LAYOUT GUIDELINES
Care must be taken when creating a PCB layout to mini-
mize power supply decoupling and ground inductances.
All power supply V+ pins should be bypassed directly to
the ground plane using a 0.1μF ceramic capacitor as close
to the pin as possible. Multiple vias to the ground plane
should be used for all ground connections, including to
the power supply decoupling capacitors.
The package’s exposed pad is a ground connection, and
must be soldered directly to the PCB land. The PCB land
pattern should have multiple thermal vias to the ground
plane for both low ground inductance and also low thermal
BALUN PIN CONFIGURATION
1 UNBALANCED PORT
2 GND OR DC FEED
3 BALANCED PORT
4 BALANCED PORT
5 GND
6 NC
Figure 20. Example of a SMT Balun Connection
6945f
24
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