
UG-1526 AD9161/AD9162/AD9163/AD9164 User Guide
Rev. 0 | Page 16 of 22
CLOCK NETWORK PERFORMANCE OPTIMIZATION
The user can measure the ADF4355 performance by the SMA
J62, as shown in Figure 3. The loop filter on the evaluation
board is standard Type II, third-order low-pass filter. The user
can customize and optimize the filter by using ADIsimPLL.
The ADF4355 register settings generated by the AD916x
Startup Wizard are typical. The user can use the standalone
ADF4355 tools (found in the zip file) to regenerate new ADF4355
settings and enter them into the register map view of the
ADF4355 by selecting ADF4355 from the dropdown menu in
the address bar, as is shown in Figure 18.
0160-018
Figure 18. Dropdown Menu to Select ADF4355
The ADF4355 phase frequency detector (PFD) spur level is
related to the PFD frequency. A lower PFD frequency can help
reduce the PFD spur, which also narrows the loop bandwidth
and affects the PLL output phase noise. The PFD frequency
used in the AD916x Startup Wizard is from 20 MHz to
50 MHz. The user can choose the PFD frequency according to
the phase noise requirement and the PFD spur requirement.
Spurious Signals Caused by the Evaluation Board
There is a divide by 4 divider (HMC362) on the evaluation
board for providing the serializer/deserializer (SERDES)
reference clock to the FPGA. The divider causes a ½ DAC clock
rate spur to be shown on the ADF4355 output. For example,
there is a 2.5 GHz spur on the ADF4355 output if the DAC
clock rate is set to 5 GHz. The spur level is around −55 dBc. The
half DAC clock rate spur can mix with the DAC output to
generate two new spurs (½ DAC update rate (fDAC) ± output
frequency (fOUT)) if using the ADF4355 as a clock source.
The user may see these two additional spurs (½ fDAC ± fOUT) at
the DAC output. These two spurs are not caused by the DAC.
The spurs disappear if an external clock is used instead.
Figure 19 shows the DAC spur differences between the on-
board clock ADF4355 and an external clock. The spur in the
red circle in Figure 19 is at ½ fDAC − fOUT.
ADF4355 AS
CLOCK SOURCE
SMA100 AS
CLOCK SOURCE
½fDAC – fOUT
0
∆Mkr2 1.784GHz
–75.051dB
REF 8.00dBm
–2
–12
(dB)
–22
–32
–42
–52
–62
–72
–82
–92 START 319MHz
#RES BW 30kHz VBW 30kHz
STOP 6.000GHz
SWEEP 153.9ms (1001pts)
20160-019
Figure 19. DAC Output Spur Differences with Different Clock Sources,
ADF4355 and External Clock SMA100
AD9161, AD9162, AD9163, and AD9164 Modes Not
Supported by the Evaluation Board
Due to the divide by 4 circuit implemented on the evaluation
board, several interpolation rates and lane counts related to the
3× interpolator are not supported on the evaluation board. These
include 3×, six lanes and 6×, three lanes.
The interpolation and lane count do not result in an integer
divisible by 4, which is a requirement for the evaluation board.
In the case of using three lanes or six lanes, the user must multiply
the default vector length of 16,384 by the lane number to ensure
that the DPGDownloader pattern is correctly sized. Otherwise,
the pattern is not correctly played from the pattern generator.
ACE USER GUIDE
A comprehensive ACE user guide is available on the Analog
Devices website. For any general information relating to the
ACE tool, refer to the ACE user guide on the Analog Devices
website.
The ACE software window is shown in Figure 20. In this view,
the tab for the AD9162 evaluation board, the AD9162 device,
and the AD9162 memory map are shown near Label 1, along with
three tabs for each of the start-up scripts used in this user guide.
The user can click each tab to navigate to the various windows.
In the Select View section (Label 2), the user can choose the
memory map view as Registers or Bit Fields.
In the Registers view (Label 4), the full registers are shown, and
some registers are expanded to show the bit field names and the
detail that the user can view.
In the Bit Fields view, the bit fields are listed alphabetically and
have widgets to control them and set bits, whereas in the Registers
view, the control is by bit or hexadecimal word. Both views can
program the registers and are based on user preference.
Because the AD9161, AD9162, AD9163, and AD9164 have a
large register map, the Functional Groups section (Label 3)
allows the user to reduce the number of registers to view at a
time.