Clock Circuitry - Analog Devices EVAL-AD4080-FMCZ User Manual

User Guide
SUPPORTED CONFIGURATIONS

CLOCK CIRCUITRY

Using an External Clock Source
The EVAL-AD4080-FMCZ allows bypassing of the
thesizer and supplying the AD9508
The following hardware changes must be applied:
Remove the C137 and C138 capacitors.
►
Populate R65 and R68 with 0 Ω resistors.
►
The user is still required to enter the desired sampling frequency
in the EVAL-AD4080-FMCZ tab in the
as the ACE Software plug-in is unaware of the external clock
Table 2. Sampling Frequency Configuration with an External Clock Source (CLKIN)
Desired Sampling Frequency
(Value Input in ACE Software
GUI) AD9508 Clock Dividers
40 MSPS to 20 MSPS CNV_P , CNV_N (OUT2, OUT2):
CLKIN divide by 10,
CLK_P, CLK_N (OUT3, OUT3):
CLKIN divide by 1
19.999 MSPS to 10 MSPS CNV_P , CNV_N (OUT2, OUT2):
CLKIN divide by 20,
CLK_P, CLK_N (OUT3, OUT3):
CLKIN divide by 2
9.999 MSPS to 5 MSPS CNV_P , CNV_N (OUT2, OUT2):
CLKIN divide by 40,
CLK_P, CLK_N (OUT3, OUT3):
CLKIN divide by 4
4.999 MSPS to 2.5 MSPS CNV_P , CNV_N (OUT2, OUT2):
CLKIN divide by 80,
CLK_P, CLK_N (OUT3, OUT3):
CLKIN divide by 8
2.499 MSPS to 1.25 MSPS CNV_P , CNV_N (OUT2, OUT2):
CLKIN divide by 160,
CLK_P, CLK_N (OUT3, OUT3):
CLKIN divide by 16
analog.com
ADF4350 syn-
directly with an external clock.
ACE Software. However,
Steps
1. Set the external CLKIN frequency to the desired
sampling Frequency x10.
2. Input the desired sampling frequency in MHz into
the ACE Software GUI (see
1. Set the external CLKIN frequency to the desired
sampling frequency x20.
2. Input the desired sampling frequency in MHz into
the ACE Software GUI (see
1. Set the external CLKIN frequency to the desired
sampling frequency x40.
2. Input the desired sampling frequency in MHz into
the ACE Software GUI (see
1. Set the external CLKIN frequency to the desired
sampling frequency x80.
2. Input the desired sampling frequency in MHz into
the ACE Software GUI (see
1. Set the external CLKIN frequency to the desired
sampling frequency x160.
2. Input the desired sampling frequency in MHz into
the ACE Software GUI (see
frequency, the user must take into account the divider factors that
the ACE Software applies to the AD9508 and adjust the external
clock frequency accordingly to effectively achieve the desired sam-
pling rate. Table 2 describes how to choose the required external
clock frequency for a desired sampling frequency. Entering a new
sampling frequency in the ACE Software GUI also resynchronizes
the AD4080 LVDS data with the ZedBoard host controller, which
mandates that the external frequency be set before inputting the
desired sample rate value through the ACE Software GUI. For
example, for 40 MHz sampling, the input CLKIN frequency is first
set to 400 MHz, and then, the ACE Software GUI is set to the
desired 40 MHz frequency.
Figure 10).
Figure 10).
Figure 10).
Figure 10).
Figure 10).
EVAL-AD4080
External CLKIN Range
400 MHz to 200 MHz,
CLKIN = 400 MHz for 40 MSPS,
CLKIN = 200 MHz for 20 MSPS
399.98 MHz to 200 MHz,
CLKIN = 399.98 MHz for 19.999 MSPS,
CLKIN = 200 MHz for 10 MSPS
399.96 MHz to 200 MHz,
CLKIN = 399.96 MHz for 9.999 MSPS,
CLKIN = 200 MHz for 5 MSPS
399.92 MHz to 200 MHz,
CLKIN = 399.92 MHz for 4.999 MSPS,
CLKIN = 200 MHz for 2.5 MSPS
399.84 MHz to 200 MHz,
CLKIN = 399.84 MHz for 2.499 MSPS,
CLKIN = 200 MHz for 1.25 MSPS
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