NRF403 Datasheet, PDF (7/15 Pages) List of Unclassifed Manufacturers – 315/433 MHz Single Chip RF Transceiver

PRODUCT SPECIFICATION
nRF403 Single Chip RF Transceiver
APPLICATION INFORMATION
Antenna input/output
The ANT1 and ANT2 pins provide RF input to the LNA (Low Noise Amplifier) when
nRF403 is in receive mode, and RF output from the PA (Power Amplifier) when
nRF403 is in transmit mode. The antenna connection to nRF403 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 nRF403 by using
a differential to single ended matching network (BALUN) as shown in Figure 7, 433
MHz and 315 MHz operation.
ANT1
xxx nRF403
ANT2
27pF
18nH
470pF ^{RF in/out 50 ohm}
18nH
27pF
2.2pF
18nH
VDD
470pF
ANT1
nRF403
ANT2
15pF
18nH
470pF ^{RF in/out 50 ohm xxx}
18nH
15pF
18nH
VDD
470pF
a) 315MHz
b) 433MHz
Figure 7. Connection of nRF403 to single ended antenna by using
a differential to single ended matching network for 433 and 315 MHz.
A single ended antenna may also be connected to nRF403 using an 8:1 impedance RF
transformer, both 315/433 MHz operation. The RF transformer must have a centre tap
at the primary side for VDD supply.
Nordic VLSI ASA -
Revision: 1.1
Vestre Rosten 81, N-7075 Tiller, Norway -
Page 7 of 18
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July 2001