NRF401 Datasheet, PDF (7/18 Pages) List of Unclassifed Manufacturers – 433MHz Single Chip RF Transceiver

PRODUCT SPECIFICATION
nRF401 Single Chip RF Transceiver
APPLICATION INFORMATION
Antenna input/output
The ANT1 and ANT2 pins provide RF input to the LNA (Low Noise Amplifier) when
nRF401 is in receive mode, and RF output from the PA (Power Amplifier) when
nRF401 is in transmit mode. The antenna connection to nRF401 is differential and the
recommended load impedance at the antenna port is 400Ω.
Figure 12 shows a typical application schematic with a differential loop antenna on a
Printed Circuit Board (PCB). The output stage (PA) 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 12.
A single ended antenna or 50Ω test instrument may be connected to nRF401 by using
a differential to single ended matching network (BALUN) as shown in Figure 7.
ANT1
nRF401
ANT2
180nH
18nH
RF in/out 50 ohm
1.8pF
18nH
470pF
VDD
Figure 7. Connection of nRF401 to single ended antenna by using
a differential to single ended matching network.
The 180nH inductor to VDD in Figure 7, need to have a Self-Resonance Frequency
(SRF) above 433 MHz to be effective. Suitable inductors are listed in Table 6.
Vendors
Stetco
Coilcraft
muRata
WWW address
http://www.stetco.com
http://www.coilcraft.com
http://www.murata.com
Part. no., 180 nH inductors,
0603 size
0603G181KTE
0603CS-R18XJBC
LQW1608AR18J00
Table 6. Vendors and part. no. for suitable 180nH inductors.
Nordic VLSI ASA -
Revision: 1.5
Vestre Rosten 81, N-7075 Tiller, Norway -
Page 7 of 18
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May 2000