What is the minimum channel Bandwidth and Data Rate possible with AX5043 when using 38.4 MHz and 10 MHz TCXO?
Hello! Thanks for posting on our Community Forum.
The best way to explore the capabilities of our AX5043 is to evaluate it using one of our development kits programmed with AX-RadioLab. The GUI will help you define the best register configuration for your desired PHY and, under the hood, it provides some error checking by suggesting to adapt values that are not compatible (e.g. RX bandwidth compatible with the chosen AFC range depending on the XTAL/TCXO precision).
To answer more in general to your question, the TCXO frequency must be chosen mainly to avoid having spurs close in to the carrier frequency. The position of these spurs can be calculated with the below formula, where N is the integer multipleof the xtal/tcxo frequency:
The channel bandwidth has to be set in order to accommodate for the signal bandwidth and take into account the frequency error of the transmitter and receiver. The signal bandwidth depends on the data rate (for the AX5043 data rate can go from 100 bps to 125 kbps), while the frequency error will be dominated by the precision (in ppm) of the XTAL/TCXO reference oscillator for the TX and RX and can be in the worst case equal to 4 * X ppm, resulting in: