1 GSPS Direct Digital
Synthesizer with 14-Bit DAC
AD9912
Rev. D
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FEATURES
1 GSPS internal clock speed (up to 400 MHz output directly)
Integrated 1 GSPS 14-bit DAC
48-bit frequency tuning word with 4 µHz resolution
Differential HSTL comparator
Flexible system clock input accepts either crystal or external
reference clock
On-chip low noise PLL REFCLK multiplier
2 SpurKiller channels
Low jitter clock doubler for frequencies up to 750 MHz
Single-ended CMOS comparator; frequencies of <150 MHz
Programmable output divider for CMOS output
Serial I/O control
Excellent dynamic performance
Software controlled power-down
Available in two 64-lead LFCSP packages
Residual phase noise @ 250 MHz
10 Hz offset: −113 dBc/Hz
1 kHz offset: −133 dBc/Hz
100 kHz offset: −153 dBc/Hz
40 MHz offset: −161 dBc/Hz
APPLICATIONS
Agile LO frequency synthesis
Low jitter, fine tune clock generation
Test and measurement equipment
Wireless base stations and controllers
Secure communications
Fast frequency hopping
GENERAL DESCRIPTION
The AD9912 is a direct digital synthesizer (DDS) that features
an integrated 14-bit digital-to-analog converter (DAC). The
AD9912 features a 48-bit frequency tuning word (FTW) that
can synthesize frequencies in step sizes no larger than 4 μHz.
Absolute frequency accuracy can be achieved by adjusting the
DAC system clock.
The AD9912 also features an integrated system clock phase-
locked loop (PLL) that allows for system clock inputs as low
as 25 MHz.
The AD9912 operates over an industrial temperature range,
spanning −40°C to +85°C.
BASIC BLOCK DIAGRAM
FDBK_IN
DAC_OUT
AD9912
S1 TO S4
OUT
OUT_CMOS
FILTER
SYSTEM CLOCK
MULTIPLIER
SERIAL PORT,
I/O LOGIC
CLOCK
OUTPUT
DRIVERS
DIGITAL
INTERFACE
06763-
001
DIRECT
DIGITAL
SYNTHESIS
CORE
STARTUP
CONFIGURATION
LOGIC
Figure 1.
