RF64 Datasheet, PDF (16/76 Pages) List of Unclassifed Manufacturers – ADVANCED COMMUNICATIONS & SENSING

RF64
ADVANCED COMMUNICATIONS & SENSING
Note for mass production: The VCO capacitance is piece to piece dependant. As such, the optimization proposed
above should be verified on several prototypes, to ensure that the population is centered on 150 mV.
3.2.6. PLL Loop Filter
To adequately reject spurious components arising from the comparison frequency Fcomp, an external 2^nd order
loop filter is employed.
RL1
LF_M
CL2
CL1
LF_P
Figure 7: Loop Filter
Following the recommendations made in section 3.2.4, the loop filter proposed in the reference design‟s bill of
material on section 7.5.3 should be used. The loop filter settings are frequency band independent and are hence
relevant to all implementations of the RF64.
3.2.7. PLL Lock Detection Indicator
The RF64 also features a PLL lock detect indicator. This is useful for optimizing power consumption, by adjusting
the synthesizer wake up time (TS_FS), since the PLL startup time is lower than specified under nominal conditions.
The lock status can be read on bit IRQParam_PLL_lock, and must be cleared by writing a “1” to this same register.
In addition, the lock status can be reflected in pin 23 PLL_LOCK, by setting the bit IRQParam_Enable_lock_detect.
3.2.8. Frequency Calculation
As shown in Figure 5 the PLL structure comprises three different dividers, R, P and S, which set the output
frequency through the LO. A second set of dividers is also available to allow rapid switching between a pair of
frequencies: R1/P1/S1 and R2/P2/S2. These six dividers are programmed by six bytes of the register MCParam
from addresses 6 to 11.
3.2.8.1. FSK Mode
The following formula gives the relationship between the local oscillator, and R, P and S values, when using FSK
modulation.
Frf , fsk  ⁹ Flo
8
Frf , fsk  ^{9 Fxtal} 75P  1)  S 
8 R 1
3.2.8.2. OOK Mode
Due to the manner in which the baseband OOK symbols are generated, the signal is always offset by the FSK
frequency deviation (Fdev - as programmed in MCParam_Freq_dev). Hence, the center of the transmitted OOK
signal is:
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