Single-Chip Low Power RF Transceiver for Narrowband Systems ...

CC1021
Loop C6 C7 C8 R2 R3 PLL turn-on time
Comment
filter no. [nF] [pF] [pF] [kΩ] [kΩ] [us]
1 56 2200 560 3.3 10 1400 Up to 9.6 kBaud data rate.
±5 kHz settling accuracy
2 15 560 150 5.6 18 1300 Up to 19.2 kBaud data rate.
±10 kHz settling accuracy
3 3.9 120 33 12 39 1080 Up to 38.4 kBaud data rate.
±15 kHz settling accuracy
4 1.0 27 3.3 27 82 950 Up to 76.8 kBaud data rate.
±20 kHz settling accuracy
5 0.2 1.5 - 47 150 700 Up to 153.6 kBaud data rate.
±50 kHz settling accuracy
Table 25. Typical PLL turn-on time to within
specified
accuracy for different loop filter
bandwidths.
15.4. PLL Lock Time versus Loop Filter Bandwidth
If calibration has been performed the PLL
lock
time is the time needed for the PLL to
lock
to the desired frequency when going
from RX to TX mode or vice versa. The
PLL lock time depends on the PLL loop
filter bandwidth. Table 26 gives the PLL
lock time for different PLL loop filter
bandwidths.
Loop C6 C7 C8 R2 R3 PLL lock time
Comment
filter [nF] [pF] [pF] [kΩ] [kΩ]
[us]
no.
1 2 3
1 56 2200 560 3.3 10 400 140 490 Up to 9.6 kBaud
data rate.
(50 kHz)
±5 kHz settling accuracy
2 15 560 150 5.6 18 140 70 230 Up to 19.2 kBaud
data rate.
(100 kHz)
±10 kHz settling accuracy
3 3.9 120 33 12 39 75 50 180 Up to 38.4 kBaud data rate.
(150 kHz)
±15 kHz settling accuracy
4 1.0 27 3.3 27 82 30 15 55 Up to 76.8 kBaud data rate.
(200 kHz)
±20 kHz settling accuracy
5 0.2 1.5 - 47 150 14 14 28 Up to 153.6 kBaud data rate.
(500 kHz)
±50 kHz settling accuracy
Table 26. Typical PLL lock time t o within specified accuracy for different loop filter
bandwidths. 1) 307.2 kHz step, 2) step as given in brackets, 3) 1 MHz step.
16. VCO and LNA Current Control
The VCO current is programmable and
should be set according to operating
frequency, RX/TX mode and output power.
Recommended settings for the
VCO_CURRENT bits in the VCO register
are shown in the register overview and
also given by SmartRF ® Studio. The VCO
current for frequency FREQ_A and
FREQ_B can be programmed
independently.
The bias currents for the LNA, mixer and
the LO and PA buffers are also
programmable. The FRONTEND and the
BUFF_CURRENT registers control these
currents.
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