ADF4150HVBCPZ AD [Analog Devices], ADF4150HVBCPZ Datasheet - Page 26

• Manufacturer Part Number: ADF4150HVBCPZ
• Description: High Voltage, Fractional-N
• Manufacturer: AD [Analog Devices]

ADF4150HV
OUTPUT MATCHING
The output of the
ways for optimum operation; the most basic is to connect a 50 Ω
resistor to AV
in series, as shown in Figure 33. Because the resistor is not fre-
quency dependent, this method provides a good broadband
match. When connected to a 50 Ω load, this circuit typically
gives a differential output power equal to the values chosen by
Bits[DB4:DB3] in Register 4.
Another solution is to connect a shunt inductor (acting as an RF
choke) to AV
band match and, therefore, more output power. However, because
the output stage is open-collector, it is recommended that a
termination resistor be used in addition to the RF choke to give
a defined output impedance. The termination resistor can be
either 50 Ω in parallel with the RF choke or 100 Ω connected
across the RF output pins.
DD
DD
Figure 33. Simple
. This solution can help provide a better narrow-
. A dc bypass capacitor of 100 pF is connected
RF
AV
ADF4150HV
OUT
DD
50Ω
ADF4150HV
100pF
can be matched in a number of
Output Stage
50Ω
Rev. 0 | Page 26 of 28
The circuit shown in Figure 34 provides a good broadband
match to 50 Ω for frequencies from 250 MHz to 3.0 GHz. The
maximum output power in this case is approximately 5 dBm.
The inductor can be increased for operation below 250 MHz.
Both single-ended architectures can be examined using the
EVAL-ADF4150HVEB1Z evaluation board.
If differential outputs are not needed, the unused output can be
terminated, or both outputs can be combined using a balun.
Figure 34. Optimum
RF
RF
OUT
OUT
AV
AV
DD
DD
+
–
22nH
100Ω
22nH
1nF
1nF
ADF4150HV
50Ω
50Ω
Output Stage
50Ω
50Ω