adf5001 Analog Devices, Inc., adf5001 Datasheet - Page 8

• Manufacturer Part Number: adf5001
• Description: 4 Ghz To 18 Ghz Divide-by-4 Prescaler
• Manufacturer: Analog Devices, Inc.

ADF5001
APPLICATION CIRCUIT
The ADF5001 can be connected either single-ended or differen-
tially to any of the Analog Devices PLL family of ICs. It is recom-
mended to use a differential connection for best performance
and to achieve maximum power transfer. The application circuit
shown in Figure 10 shows the ADF5001 used as the RF prescaler
in a microwave 16 GHz PLL loop. The ADF5001 divides down
the 16 GHz RF signal to 4 GHz, which is input differentially
into the
OP184
op amp, is used to provide the wide tuning ranges
ADF4156
RFIN
PLL. An active filter topology, using the
VDD1
150Ω
ADF5001
PRESCALER
6dB PAD
37Ω
GND
VDD2
10pF
150Ω
RFOUTB
RFOUT
16GHz OUT
Figure 10. ADF5001 Used as the RF Prescaler in a Microwave 16 GHz PLL Loop
0.1µF
18Ω
DECOUPLING
INTEGRATED
18Ω
RFOUT
RF
RF
MICROWAVE
IN
IN
B
A
ADF4156
Rev. 0 | Page 8 of 12
VCO
PLL
VTUNE
CP
typically required by microwave VCOs. The positive input pin of
the OP184 is biased at half the ADF4156 charge pump supply
(VP). This can be easily achieved using a simple resistor divider,
ensuring sufficient decoupling close to the +IN A pin of the
OP184. This then allows the use of a single positive supply for the
op amp. Alternatively, to optimize performance by ensuring a
clean bias voltage, a low noise regulator like the ADP150 can be
used to power the resistor divider network or the +IN A pin
directly.
820pF
220Ω
VP/2
330Ω
1µF
OP AMP
OP184
1.8nF
47nF
1kΩ
1.8nF