| Номер запчасти | AD9851 |
| Производитель | Analog Devices |
| Краткое описание | 180 MHz Complete DDS synthesizer |
| Страниц | 24 шт. |
| Формат | |
| Размер | 261,05 kB |
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AD9851
CMOS 180 MHz
DDS/DAC Synthesizer
FEATURES
180 MHz Clock Rate with Selectable 6 Reference Clock
Multiplier
On-Chip High Performance 10-Bit DAC and High Speed
Comparator with Hysteresis
SFDR >43 dB @ 70 MHz A OUT 32-Bit Frequency Tuning Word
Simplifi ed Control Interface: Parallel or Serial
Asynchronous Loading Format
5-Bit Phase Modulation and Offset Capability
Comparator Jitter <80 ps p-p @ 20 MHz
2.7 V to 5.25 V Single-Supply Operation
Low Power: 555 mW @ 180 MHz
Power-Down Function, 4 mW @ 2.7 V
Ultrasmall 28-Lead SSOP Packaging
APPLICATIONS
Frequency/Phase-Agile Sine Wave Synthesis
Clock Recovery and Locking Circuitry for Digital
Communications
Digitally Controlled ADC Encode Generator
Agile Local Oscillator Applications in Communications
Quadrature Oscillator
CW, AM, FM, FSK, MSK Mode Transmitter
FUNCTIONAL BLOCK DIAGRAM
32-BITTUNINGWORD
PHASEANDCONTROLWORDS
FREQUENCY/PHASEDATA REGISTER
DATA INPUT REGISTER
10-BITDAC
DAC RSET
ANALOGOUT
ANALOGIN
CLOCK OUT
CLOCK OUT
HIGH SPEED DDS
FREQUENCYUPDATE/DATA REGISTER RESET WORD LOAD CLOCK
MASTERRESET
REF CLOCK IN 6 REFCLKMULTIPLIER
COMPARATOR SERIALLOAD
1 BIT 40 LOADSPA
RALLELLOAD
8 BITS
5 LOADS
FREQUENCY, PHASE AND CONTROL DATA INPUT
AD9851
+VS GND
GENERAL DESCRIPTION
The AD9851 is a highly integrated device that uses advanced
DDS technology, coupled with an internal high speed, high
performance D/A converter, and comparator, to form a dig i tal ly
programmable frequency synthesizer and clock generator func-
tion. When referenced to an accurate clock source, the AD9851
generates a stable frequency and phase-programmable digitized
analog output sine wave. This sine wave can be used directly as
a frequency source, or internally converted to a square wave for
agile-clock generator applications. The AD9851’s innovative
high speed DDS core accepts a 32-bit frequency tuning word,
which results in an output tuning res o lu tion of approximately
0.04 Hz with a 180 MHz system clock. The AD9851 con tains
a unique 6 REFCLK Multiplier circuit that eliminates the
need for a high speed reference oscillator. The 6 REFCLK
Multiplier has min i mal impact on SFDR and phase noise char-
ac ter is tics. The AD9851 provides fi ve bits of programmable
phase mod u la tion resolution to enable phase shifting of its
output in in cre ments of 11.25°.
The AD9851 contains an internal high speed comparator that
can be confi gured to accept the (externally) fi ltered output of the
DAC to generate a low jitter output pulse.
The frequency tuning, control, and phase modulation words are
asynchronously loaded into the AD9851 via a parallel or serial
loading format. The parallel load format consists of fi ve it er a tive
loads of an 8-bit control word (byte). The fi rst 8-bit byte controls
output phase, 6 REFCLK Multiplier, power-down enable and
loading for mat; the remaining bytes comprise the 32-bit frequency
tuning word. Serial loading is accomplished via a 40-bit serial data
stream entering through one of the parallel input bus lines. The
AD9851 uses advanced CMOS technology to provide this break-
through level of functionality on just 555 mW of power dissipation
(5 V supply), at the maximum clock rate of 180 MHz.
The AD9851 is available in a space-saving 28-lead SSOP,
surface-mount package that is pin-for-pin compatible with the
popular AD9850 125 MHz DDS. It is specifi ed to operate over
the extended industrial temperature range of –40°C to +85°C
at >3.0 V supply voltage. Below 3.0 V, the specifi cations apply
over the commercial temperature range of 0°C to 85°C.
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