NRF0433 Datasheet, PDF (9/14 Pages) List of Unclassifed Manufacturers – Single chip 433MHz RF Transceiver

PRODUCT SPECIFICATION
nRF0433 Single chip RF Transceiver
of +/- 35 ppm for the transmitter and receiver. Additional frequency difference will
result in a -12dB/octave drop in receiver sensitivity. The functional window of the
transmission link is typically 450 ppm (200 kHz).
Example: A crystal with +/- 20 ppm frequency tolerance and +/- 25 ppm frequency
stability over temperature (-25C to +75C) has a worst case frequency difference of 45
ppm. If the transmitter and receiver operate in different temperature environments, the
resulting worst-case frequency difference may be as high as 90 ppm. Resulting drop in
sensitivity due to the extra 20 ppm, is then approx. 5dB.
PCB layout and decoupling guidelines
A well-designed PCB is necessary to achieve good RF performance. A PCB with a
minimum of two layers inclusive a ground plane is recommended for optimum
performance.
The nRF0433 +5V DC supply voltage should be decoupled as close as possible to the
VDD pins with a high performance RF capacitor (e.g. 100 pF ceramic). It is preferable
to mount a large surface mount capacitor (e.g. 2.2 µF ceramic) in parallel with the
smaller value capacitors. The nRF0433 supply voltage should be filtered separately
from the supply voltages of any digital circuitry.
Long power supply lines on the PCB should be avoided. All device grounds, VDD
connections and VDD bypass capacitors must be connected as close as possible to the
IC package. For a PCB with a topside RF ground plane, the VSS pins should be
connected directly to the ground plane. For a PCB with a bottom ground plane, the
best technique to connect the VSS pins to ground, is to have via holes in, or close to
the VSS pad.
Full swing digital data or control signals should not be routed close to the PLL loop
filter and the external VCO inductor.
The VCO inductor placement is important. The optimum placement of the VCO
inductor gives a PLL loop filter voltage of 1.25 +/- 0.5 V. For a 0805 size inductor the
length between the centre of the VCO1(2) pad and the centre of the inductor pad
should be 2.5 mm, see figure 8 (layout, top view).
PCB layout example
Figure 8 shows a PCB layout example for the application schematic in Figure 7.
A double-sided FR-4 board of 1.6mm thickness is used. This PCB has a continuous
ground plane on the bottom layer. Additionally, there are ground areas on the
component side of the board to ensure sufficient grounding of critical components. A
large number of via holes connect the top layer ground areas to the bottom layer
ground plane. There is no ground plane behind the antenna.
For more layout information, please refer to application note nAN400-04,
“nRF0433 RF and antenna layout”.
Nordic VLSI ASA - Vestre Rosten 81, N-7075 Tiller, Norway -
Revision: 3.2
Page 9 of 14
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February 2000