EVAL-ADF7020DB1 Analog Devices Inc, EVAL-ADF7020DB1 Datasheet - Page 3

• Manufacturer Part Number: EVAL-ADF7020DB1
• Description: BOARD EVAL ADF7020 902-928MHZ
• Manufacturer: Analog Devices Inc

Specifications of EVAL-ADF7020DB1

• Module/board Type: Evaluation Board
• For Use With/related Products: ADF7020 928MHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Preliminary Technical Data
Output Matching Circuit
The ADF7020/ADF7020-1 exhibits optimum performance in
terms of sensitivity, transmit power, and current consumption,
only if its RF input and output ports are properly matched to
the antenna impedance. For cost-sensitive applications, the
ADF7020/ADF7020-1 is equipped with an internal Rx/Tx
switch, which facilitates the use of a simple combined passive
PA/LNA matching network as outlined in Figure 6. Please refer
to Datasheet for more details.
For ease of design the matching and harmonic filter
components are provided for the most commonly used bands
(see Table5-8) Please refer to Application Note AN-764 and
Application Note AN-859 for more details on PA/LNA
matching for the ADF7020 and ADF7020-1 devices.
Antenna
CHOICE OF VCO INDUCTOR FOR ADF7020-1
The ADF7020-1 uses the same VCO core as the ADF7020 but
with the VCO tank inductor (L3) external to allow the user to
set the operating frequency. The frequency of oscillation can be
Harmonic
Filter
Figure 5.. LNA/PA Output Matching Circuit
C3
C2
C1
L2
Vbat
Zopt_pa
L1
Zin_rfin
Zin_rfin
PA_OUT
RFINB
ADF7020
RFIN
+
-
LNA
PA
Rev. Pr C | Page 3 of 19
approximated using the following formula:
The length of the PCB track to the external inductor pad will
effect the total L
external inductor value as measured on the EVAL-ADF7020-
1DBX boards is shown in Figure7. If you are using a different
length of PCB track to the ADI Evaluation boards you need to
take this into consideration. ADIsimPLL will give you the total
external inductance (chip inductor + PCB track) needed for a
given frequency range so that your desired frequency band lies
in the middle of the range where possible. It is also possible to
shift the frequency by use of the VCO Adjust bits which has the
effect of adjusting C
F
590
570
550
530
510
490
470
450
430
410
390
370
350
330
310
290
270
250
230
210
190
170
VCO
0
Figure 6. Direct Output Frequency vs. External Inductor Value(L3)
1
=
2
2
3
ADF7020-1 output frequency vs. external inductor value
π
4
5
(
EXT
L
6
INT
: The ADF7020-1 VCO Frequency range vs.
7
VAR.
8
+
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
L
EXT
1
) (
×
EVAL-ADF7020DBX
C
VAR
+
C
FIXED
)