EVAL-ADF7021-NDBZ2 Analog Devices Inc, EVAL-ADF7021-NDBZ2 Datasheet - Page 25

• Manufacturer Part Number: EVAL-ADF7021-NDBZ2
• Description: 860 MHz To 870 MHz
• Manufacturer: Analog Devices Inc
• Type: Transceiver, FSKr

Specifications of EVAL-ADF7021-NDBZ2

• Frequency: 860MHz ~ 870MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ADF7021-N
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Table 9. RF Output Frequency Ranges for Internal and External Inductor VCOs and Required Register Settings
RF Frequency
Output (MHz)
870 to 916
842 to 870
440 to 458
421 to 440
450 to 650
200 to 450
80 to 200
CHOOSING CHANNELS FOR BEST SYSTEM
PERFORMANCE
An interaction between the RF VCO frequency and the
reference frequency can lead to fractional spur creation. When
the synthesizer is in fractional mode (that is, the RF VCO and
reference frequencies are not integer related), spurs can appear
on the VCO output spectrum at an offset frequency that
corresponds to the difference frequency between an integer
multiple of the reference and the VCO frequency.
VCO to
Be Used
Internal L
Internal L
Internal L
Internal L
External L
External L
External L
RF Divide
by 2
No
No
Yes
Yes
No
No
Yes
VCO_INDUCTOR
R1_DB25
0
0
0
0
1
1
1
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RF_DIVIDE_BY_2
R1_DB18
0
0
1
1
0
0
1
These spurs are attenuated by the loop filter. They are more
noticeable on channels close to integer multiples of the reference
where the difference frequency may be inside the loop bandwidth;
thus, the name integer boundary spurs. The occurrence of these
spurs is rare because the integer frequencies are around multiples
of the reference, which is typically >10 MHz. To avoid having
very small or very large values in the fractional register, choose
a suitable reference frequency.
Register Settings
VCO_ADJUST
R1_DB[23:24]
11
00
11
00
XX
XX
XX
VCO_BIAS
R1_DB[19:22]
8
8
8
8
4
3
2
ADF7021-N