AD9643/AD9613/AD6649/AD6643 User Guide
UG-293
Rev. A | Page 9 of 26
5.
If using the
AD6649
, the device can be configured into two
different modes. The default mode utilizes a 95 MHz FIR
filter and fixed-frequency NCO. The SPI controller settings
for this mode are shown in Figure 12. Under the
MAIN(50)
section, the
Fir Low Latency Mode En
checkbox must be
selected, and the
Low Latency NCO (Fs/4 Only)
option
must be selected under the
MISC EXTRA(5A)
section.
The second mode uses a 100 MHz FIR filter and a tunable-
frequency NCO (see Figure 13). In this mode, the
High
Latency NCO
option under
MISC EXTRA(5A)
must be
selected, and the
Fir Low Latency Mode En
checkbox
must be cleared under the
MAIN(50)
section.
099
40
-01
2
Figure 12. SPI Controller,
AD6649
ADC A Tab—95 MHz FIR Filter and Fixed-Frequency NCO Mode