NRF902 Datasheet, PDF (7/13 Pages) List of Unclassifed Manufacturers – Single chip 868 MHz Transmitter

PRELIMINARY PRODUCT SPECIFICATION
nRF902 Single chip 868 MHz Transmitter
ASK modulation.
ASK modulation can be realised by using the REXT pin (see Figure 8). When R2 is
connected to VDD, the chip transmits a carrier. When the bias resistor is connected to
VSS then the internal output power amplifier is turned off. These two situations
represent logic ‘1’ and logic ‘0’ in an ASK system. When ASK modulation is used,
the FSK pin must be connected to VDD.
X1 13.567MHz
VDD
Data
Input
Clock
Output
VDD
R1
xtal ¹
R2
2
REXT
3
XO8
VDD ⁴
C1
C2
nRF902
8 _VSS
7 _ant1
6 _ant2
5
FSK
Matching Network/
Antenna
VDD
Figure 8. FSK transmitter in ASK Transmit mode
Antenna output
The “ant” output pins provide a balanced RF output to the antenna. The pins must
have a DC path to V_DD, either via a RF choke or via the centre point in a loop antenna.
The load impedance seen between the ant1/ant2 outputs should be in the range 200-
700Ω. A load impedance of 400Ω is recommended if maximum output power
(10dBm) is needed. Lower load impedance (for instance 50 Ω) can be obtained by
fitting a simple matching network or a RF transformer (balun). The 50 Ω load can
also be connected directly between the ant1/ant2 pins, but this will result in higher
current consumption for a given output power to the antenna.
Note: Application notes of antenna layout solutions with matching networks will soon
be available on our website: http://www.nvlsi.no.
Nordic VLSI ASA
Revision: 1.0
- Vestre Rosten 81, N-7075 Tiller, Norway - Phone [phone] - Fax [phone]
Page 7 of 13
April 2000