NRF0433 Datasheet, PDF (7/14 Pages) List of Unclassifed Manufacturers – Single chip 433MHz RF Transceiver

PRODUCT SPECIFICATION
nRF0433 Single chip RF Transceiver
APPLICATION INFORMATION
Antenna input/output
The ANT1 and ANT2 pins provide RF input to the LNA when nRF0433 is in receive
mode, and RF output from the PA when nRF0433 is in transmit mode. The antenna
connection to nRF0433 is differential and the recommended impedance at the antenna
port is 400Ω.
Figure 7 shows a typical application schematic with a differential loop antenna on a
Printed Circuit Board (PCB). If a single ended 50Ω antenna is preferred, the most
convenient solution is to connect the antenna to nRF0433 using an 8:1 impedance
transformer as a balun, see figure 6a). The transformer must have a centre tap at the
primary side (primary side connected to the ANT1/ANT2 pins), as explained below.
The output stage (PA) consists of two open collector transistors in a differential pair
configuration. +5V DC to the PA must be supplied through the collector load. When
connecting a differential loop antenna to the ANT1/ANT2 pins, +5V DC should be
supplied through the centre of the loop antenna as shown in figure 7. When using an
8:1 impedance transformer as a balun, +5V DC to the PA should be supplied through
the centre tap at the primary side of the transformer as shown in figure 6a).
A single ended antenna can also be connected to nRF0433 by using the differential to
single ended matching network as shown in figure 6b). The layout of these matching
networks is critical, see application note nAN400-04, “nRF0433 RF and antenna
+5V
100pF
+5V
100pF
100nH
ANT1
1
nRF0433
82nH
2
RF in/out 50 ohm
5
ANT1
nRF0433
RF in/out 50 ohm
22nH
5.6pF
2.2pF
ANT2
3
4
ANT2
5.6pF
a)
b)
Figure 6. Connection of nRF0433 to single ended antenna by using a) a balun or
b) a differential to single ended matching network.
RF output power
Output power is set by the external bias resistor R3 connected between RF_PWR and
+5V as shown in figure 7. The RF output power can be set to one of four levels as
shown in table 5.
Nordic VLSI ASA - Vestre Rosten 81, N-7075 Tiller, Norway -
Revision: 3.2
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February 2000