RFM63B Datasheet, PDF (18/90 Pages) List of Unclassifed Manufacturers – ISM TRANSCEIVER MODULE V1.1

ADVANCED COMMUNICATIONS & SENSING
3.3. Transmitter Description
The RFM63B is set to transmit mode when MCParam_Chip_mode = 100.
RFM63B
3.3.1. Architecture Description
The baseband I and Q signals are digitally generated by a DDS whose digital to analog converters (DAC) followed
by two anti-aliasing low-pass filters transform the digital signal into analog in-phase (I) and quadrature (Q)
components whose frequency is the selected frequency deviation (Fdev).
1
Fdev
I(t)
Q(t)
Figure 9: I(t), Q(t) Overview
In FSK mode, the relative phase of I and Q is switched by the input data between -90°and +90°with co ntinuous
phase. The modulation is therefore performed at this initial stage, since the information contained in the phase
difference will be converted into a frequency shift when the I and Q signals are up-converted in the first mixer
stage. This first up-conversion stage is duplicated to enhance image rejection. The FSK convention is such that:
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