NRF402 Datasheet, PDF (6/16 Pages) List of Unclassifed Manufacturers – 433MHz Single Chip RF Transmitter

PRODUCT SPECIFICATION
nRF402 Single Chip RF Transmitter
APPLICATION INFORMATION
Antenna output
The ANT1 and ANT2 pins provide RF output from the output stage (PA) for nRF402.
The antenna connection to nRF402 is differential and the recommended load
impedance at the antenna port is 400Ω.
Figure 11 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 11.
A single ended antenna or 50Ω test instrument may be connected to nRF402 by using
a differential to single ended matching network (BALUN) as shown in Figure 6.
VDD
ANT1
nRF402
ANT2
180nH
22nH
1.8pF
22nH
470pF
VDD
1nF
RF out 50 ohm
1.5pF
22nH
Figure 6. Connection of nRF402 to single ended antenna by using
a differential to single ended matching network
The 180nH inductor to VDD in Figure 6, 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.
A single ended antenna may also be connected to nRF402 using an 8:1 impedance RF
transformer. The RF transformer must have a centre tap at the primary side for VDD
supply.
Nordic VLSI ASA
Revision: 2.1
Vestre Rosten 81, N-7075 Tiller, Norway -
Page 6 of 16
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February 2000