400 MSPS, 10-Bit, 1.8 V CMOS
Direct Digital Synthesizer
AD9859
FEATURES
APPLICATIONS
400 MSPS internal clock speed
Integrated 10-bit DAC
32-bit tuning word
Phase noise ≤ –120 dBc/Hz @ 1 kHz offset (DAC output)
Excellent dynamic performance
>75 dB SFDR @ 160 MHz ( 100 kHz offset) AOUT
Serial I/O control
1.8 V power supply
Software and hardware controlled power-down
48-lead TQFP/EP package
Support for 5 V input levels on most digital inputs
PLL REFCLK multiplier (4× to 20×)
Internal oscillator; can be driven by a single crystal
Phase modulation capability
Agile LO frequency synthesis
Programmable clock generators
Test and measurement equipment
Commercial and amateur radio exciter
GENERAL DESCRIPTION
The AD9859 is a direct digital synthesizer (DDS) featuring a
10-bit DAC operating at up to 400 MSPS. The AD9859 uses
advanced DDS technology, coupled with an internal high speed,
high performance DAC to form a digitally programmable,
complete high frequency synthesizer capable of generating a
frequency-agile analog output sinusoidal waveform at up to
200 MHz. The AD9859 is designed to provide fast frequency
hopping and fine tuning resolution (32-bit frequency tuning
word). The frequency tuning and control words are loaded into
the AD9859 via a serial I/O port.
Multichip synchronization
The AD9859 is specified to operate over the extended industrial
temperature range of –40°C to +105°C
FUNCTIONAL BLOCK DIAGRAM
DDS CORE
AD9859
PHASE
ACCUMULATOR
DAC_R
PHASE
OFFSET
SET
–1
Z
IOUT
IOUT
32
19
10
COS(X)
DAC
14
SYSTEM
CLOCK
10
–1
Z
32
SYNC_IN
14
OSK
TIMING AND CONTROL LOGIC
I/O UPDATE
SYNC_CLK
PWRDWNCTL
0
M
U
X
SYNC
CONTROL REGISTERS
÷ 4
OSCILLATOR/BUFFER
M
U
X
SYSTEM
CLOCK
4–20
REFCLK
REFCLK
CLOCK
MULTIPLIER
ENABLE
CRYSTAL OUT
I/O PORT
RESET
Figure 1.
Rev. A
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