SWRS046I November 2006 – September 2018 CC1020
PRODUCTION DATA.
The CC1020 device is specifically designed for narrowband systems complying with ARIB STD-T67 and EN 300 220. The CC1020 device meets the strict requirements to ACP (Adjacent Channel Power) and occupied bandwidth for a narrowband transmitter. To meet the ARIB STD-T67 requirements, a 3.0 V regulated voltage supply should be used.
For the receiver side, the CC1020 device gives very good ACR (Adjacent Channel Rejection), image frequency suppression and blocking properties for channel spacings down to 12.5 kHz.
Such narrowband performance normally requires the use of external ceramic filters. The CC1020 device provides this performance as a true single-chip solution with integrated IF filters.
Japan and Korea have allocated several frequency bands at 424, 426, 429, 447, 449 and 469 MHz for narrowband license free operation. The CC1020 device is designed to meet the requirements for operation in all these bands, including the strict requirements for narrowband operation down to 12.5 kHz channel spacing.
Due to on-chip complex filtering, the image frequency is removed. An on-chip calibration circuit is used to get the best possible image rejection. A narrowband preselector filter is not necessary to achieve image rejection.
A unique feature in the CC1020 device is the very fine frequency resolution. This can be used for temperature compensation of the crystal if the temperature drift curve is known and a temperature sensor is included in the system. Even initial adjustment can be performed using the frequency programmability. This eliminates the need for an expensive TCXO and trimming in some applications. For more details refer to AN027 Temperature Compensation by Indirect Method (SWRA065).
In less demanding applications, a crystal with low temperature drift and low aging could be used without further compensation. A trimmer capacitor in the crystal oscillator circuit (in parallel with C5) could be used to set the initial frequency accurately.
The frequency offset between a transmitter and receiver is measured in the CC1020 device and can be read back from the AFC register. The measured frequency offset can be used to calibrate the receiver frequency using the transmitter as the reference. For more details refer to AN029 CC1020/1021 Automatic Frequency Control (AFC) (SWRA063).
The CC1020 device also has the possibility to use Gaussian shaped FSK (GFSK). This spectrum-shaping feature improves adjacent channel power (ACP) and occupied bandwidth. In ‘true’ FSK systems with abrupt frequency shifting, the spectrum is inherently broad. By making the frequency shift ‘softer’, the spectrum can be made significantly narrower. Thus, higher data rates can be transmitted in the same bandwidth using GFSK.