SWRZ108A November 2021 – January 2022 CC1312R7
Proprietary radio modes: spurious emissions can affect regulatory compliance
Revision B
When device internal load capacitors are used with the external 48-MHz crystal, energy couples from the crystal oscillator circuit to the RF output. This coupling causes spurious emissions at N × 48 MHz from carrier frequency. This includes, but is not limited to, the frequency bands supported by the device covered by the following regulations:
When using the +14-dBm RF power amplifier
For compliance with affected standards, external load capacitors might be needed for the 48-MHz crystal to reduce spurious emissions. Internal capacitors (default 7-pF connected capacitance) must then be disconnected internally.
This workaround is implemented by defining the following symbols in the included customer configuration file (ccfg.c) available in the SimpleLink™ CC13xx and CC26xx Software Development Kit (SDK) examples:
#define SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA -128
#define SET_CCFG_MODE_CONF_XOSC_CAP_MOD 0