External Inductor Options - Analog Devices EV-ADF4360-7EB1Z User Manual

UG-104

EXTERNAL INDUCTOR OPTIONS

The ADF4360-7 uses external inductors (L1 and L2) to set up
the LC tank circuit of the VCO. The evaluation board has a
footprint for placing these inductors. A value of 3.9 nH is inserted
on the board giving a VCO center frequency of 900 MHz. For
this inductor value and for other inductor values of greater than
3.3 nH, a 470 Ω resistor in parallel to ground for both L1 and L2
must be inserted, as shown in Figure 3.
Figure 3. External Inductors and Resistors for
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ADF4360-7 Tank Circuit
Rev. B | Page 4 of 16
Evaluation Board User Guide
To find the optimum frequency range for a given inductor, see
Figure 4. Ensure that the desired frequency is between the two
lines and read off the appropriate inductance needed.
1500
1400
1300
1200
1100
1000
900
800
700
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500
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300
0 5 10
EXT INDUCTANCE (nH)
Figure 4. Output Center Frequency vs. External Inductor Value
15 20 25 30