ML7406 Family LSIs Hardware Design Manual
FEXL7406DG-01
8
4.1. Adjusting component values for VCO tank
Adjustment procedure of the VCO tank components is as below:
1.
Execute the VCO calibration with the following condition.
Set the frequency to the center of usingfrequency range.
In the idle state with the room temperature.
2.
Adjust the L1 and C1 values so that the calibration value obtained by [VCO_CAL] register (B0 0x6E)
becomes close to “64” (decimal).
Reducing one or both L1 and C1 values if decreasing the VCO_CAL value.
Increasing one or both L1 and C1 values if increasing the VCO_CAL value.
[Note] In order to lock the PLL, the VCO_CAL value is required to be in the range from 1 to 126 (decimal) under
all conditions.
The frequency range that PLL can lock, VCO phase noise and the temperature feature depend on the L1, C1
values. It is recommended to evaluate these characteristics when L1 and C1 values is fixed.
Table 4.1.1 Representative component values for operating frequency
868MHz band
L1
4.7nH
C1
4.3pF
[Note] These component values appropriate for use on the LAPIS Semiconductor’s RF board. It is not guaranteed
to obtain same result on your specific board.