Texas Instruments CC1000PP user manual Layout, Antennas, Bill of materials

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

433MHz

868MHz

915MHz

¼wavelength 16.4 cm

8.2 cm

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.

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