Texas Instruments CC1000PP - Manual (Page 8)

SWRU060 Page 8 of 11
Layout
RF circuits working at high frequencies are very sensitive to the physical layout of the PCB.
Chipcon has carefully optimised the layout of the CC1000PP in order to provide good RF
performance. Chipcon strongly recommends that you use this layout as it is, and that you do
not attempt to modify it.
LO leakage is a critical parameter. To meet the ETSI requirement of –57 dBm, coupling from
the VCO to the antenna or the matching network must be carefully controlled. The VCO
inductor must be of the specified type and be mounted with the correct alignment if LO
leakage is to meet specifications. The L101 VCO inductor should be oriented with the thick
white stripe facing the crystal. To prevent coupling via the power supply, the specified
decoupling capacitors must be mounted as shown.
Figure 4. Top and bottom PCB layout, top silkscreen
Antennas
The CC1000PP can be used together with any type of single-sided antenna. Loop antennas
can also be used by grounding one side. If the antenna’s impedance is not close to 50 ohms,
matching components should be used to match it to 50 ohms. A quarter-wave wire antenna
can be used directly by removing pins 1, 2 and 3 from P2 and soldering in a piece of wire of
the correct length (one quarter wavelength).
Frequency ¼ wavelength
433 MHz 16.4 cm
868 MHz 8.2 cm
915 MHz 7.8 cm
Table 2: 1/4 wavelength for common frequencies
For more information about antennas, please see application note AN003.
Bill of materials
The CC1000 is designed to be used together with low cost passive components. The
components specified for the CC1000PP are the same as those listed in the data sheet. The
only critical component is the VCO inductor, which must be the exact type listed in order for
LO leakage to meet specifications. All other capacitors and inductors are non-critical, and any
manufacturer or type may be used as long as they match the specifications in the component
list. The boards manufactured by Chipcon uses Coilcraft HQ-series inductors, some of the
inductor values may not be available from all manufacturers. Substituting nearby values may
be possible.