nRF903 Nordic VLSI, nRF903 Datasheet - Page 19

• Manufacturer Part Number: nRF903
• Description: Multichannel RF Transceiver 433/868/915MHz
• Manufacturer: Nordic VLSI

PRODUCT SPECIFICATION
The ANT1 and ANT2 pins provide RF input to the LNA (Low Noise Amplifier) when
nRF903 is in receive mode, and RF output from the PA (Power Amplifier) when
nRF903 is in transmit mode. The antenna connection to nRF903 is differential and the
recommended load impedance at the antenna port is 300 .
Figure 19 shows a typical application schematic with a differential loop antenna on a
Printed Circuit Board (PCB). The PA output stage consists of two open collector
transistors in a differential pair configuration. VDD to the PA must be supplied
through the collector load. When connecting a differential loop antenna to the
ANT1/ANT2 pins, VDD should be supplied through the centre of the loop antenna as
shown in Figure 19.
A single ended antenna or 50 test instrument may be connected to nRF903 by using
a differential to single ended matching network (BALUN) as shown in Figure 11.
The series-inductors L
well above the transmit/receive frequency to be effective. Suitable component values
are listed in Table 18. Gerber layout files of the matching network is available at
and C
Nordic VLSI ASA
Revision: 3.1
Figure 11. Connecting the nRF903 to a single ended antenna by using a differential to
s1
433.92 0.87
Table 18. Single-ended matching network components values for nRF903
, and 0.1pF for C
915 13
869 1
. Component tolerances are 2% for the inductors, 5% for C
Q5) 
-
Vestre Rosten 81, N-7075 Tiller, Norway
ANT1
ANT2
s
in Figure 11, need to have a Self Resonance Frequency (SRF)
p
22
12
and C
S
C
single-ended matching network.
p
s
.
C
C
s
s
39
12
Qhtrà (ÂsÃ"!
L
V
p
L
L
s
s
1.8
-
S
-
V
DD
C
Phone [phone]
s1
C
decopling
8.2
3.9
RF in/out 50 ohm
V
6.8
4.7
-
V
Fax [phone]
decoupling
December 2002
GHFRXSOLQJ
100
33