groupUrl: https://ez.analog.com/dds/
Analog.com Analog Dialogue Wiki English
Analog.com Analog Dialogue Wiki 简体中文
EngineerZone
EngineerZone
  • Site
  • User
  • Site
  • Search
  • User
EngineerZone
EngineerZone
  • Log in
  • Site
  • Search
  • Log in
  • Home
  • Blogs ⌵
  • Browse ⌵
    • All Groups
    • All Members
  • Support ⌵
    • 3D ToF Depth Sensing
    • A2B
    • Aerospace and Defense (ADEF)
    • Amplifiers
    • Analog Microcontrollers
    • Analysis Control Evaluation (ACE) Software
    • Audio
    • Clock and Timing
    • Condition-Based Monitoring
    • Data Converters
    • Design Tools and Calculators
    • Direct Digital Synthesis (DDS)
    • Embedded Vision Sensing
    • Energy Monitoring and Metering
    • FPGA Reference Designs
    • Industrial Ethernet
    • Interface and Isolation
    • Low Power RF Transceivers
    • MEMS Inertial Sensors
    • Motor Control Hardware Platforms
    • Optical Sensing
    • Power Management
    • Precision Technology Signal Chains
    • Processors and DSP
    • Reference Circuits
    • RF and Microwave
    • Signal Chain Power (SCP)
    • Switches/Multiplexers
    • Temperature Sensors
    • Video
    • Wide Band RF Transceivers
    • Wireless Sensor Networks Reference Library
  • About EZ
  • More
  • Cancel
  • 主页
  • 浏览 ⌵
    • 收件箱
    • 个人设置
    • 会员
    • 专区列表
  • 论坛专区 ⌵
    • 放大器专区
    • 精密转换器专区
    • 音频专区
    • ADE电能计量专区
    • MEMS和传感器专区
    • 接口和隔离专区
    • Power 中文专区
    • ADUC微处理器专区
    • 锁相环专区
    • 开关和多路复用器专区
    • 温度传感器
    • 基准电压源专区
    • 资源库
    • 论坛使用指南
    • 技术支持参考库
    • 在线研讨会
    • 论坛社群活动
    • 论坛激励活动
  • More
  • Cancel
Direct Digital Synthesis (DDS)
Direct Digital Synthesis (DDS)
Documents AD9851: frequency senthesis
  • Q&A
  • Discussions
  • Documents
  • Tags
  • Managers
  • More
  • Cancel
  • New
Direct Digital Synthesis (DDS) requires membership for participation - click to join
  • Documents
  • +AD5930: FAQ
  • +AD5932: FAQ
  • +AD5933: FAQ
  • +AD5934: FAQ
  • +AD9152: FAQ
  • +AD9830: FAQ
  • +AD9832: FAQ
  • +AD9833: FAQ
  • +AD9834: FAQ
  • +AD9835: FAQ
  • +AD9837: FAQ
  • +AD9838: FAQ
  • +AD9840: FAQ
  • +AD9840A: FAQ
  • +AD9845A: FAQ
  • +AD9850: FAQ
  • -AD9851: FAQ
    • AD9851: Best value for Rset
    • AD9851: frequency senthesis
    • AD9851: RESET input
  • +AD9852: FAQ
  • +AD9854: FAQ
  • +AD9854ASQ: FAQ
  • +AD9856: FAQ
  • +AD9857: FAQ
  • +AD9858: FAQ
  • +AD9859: FAQ
  • +AD9910: FAQ
  • +AD9912: FAQ
  • +AD9913: FAQ
  • +AD9914: FAQ
  • +AD9915: FAQ
  • +AD9945: FAQ
  • +AD9951: FAQ
  • +AD9952: FAQ
  • +AD9953: FAQ
  • +AD9954: FAQ
  • +AD9956: FAQ
  • +AD9957: FAQ
  • +AD9958: FAQ
  • +AD9959: FAQ
  • +DDS: FAQ
  • +Digital Ground (DGND): FAQ
  • +Evaluation Software: FAQ
  • +Frequency Ramp: FAQ
  • +I/O_UPDATE: FAQ
  • +Maximum Clock Rate: FAQ
  • +PLL: FAQ
  • +Programmable Modulus: FAQ
  • +SFDR: FAQ
  • +Thermally Enhanced Packages: FAQ

AD9851: frequency senthesis

Q 

We are looking for a frequency synthesis circuit that would allow us to inject
accurate frequencies into the RF amplifier
stage of a 173MHz transceiver unit. These frequencies need to be varied (FSK)
in accordance with a digital data stream. The
frequencies would need to be varied by up to 2400 times a second (2400 baud
data stream). My question is : would your AD9850 family
of DDS chips be suitable for such a purpose ? i.e. can the frequency generator
be accurately "modulated" at such a rate ?

 

A 

What frequencies do you require the AD9851 to generate. The maximum output
frequency of  a DDS is limited to approximately 1/3 of the master clock
frequency, so the AD9851 can generate frequencies up to about 60MHz before the
SFDR starts to become fairly horrendous.

Assuming that you want to generate frequencies up to 60MHz and mix them with a
175MHz carrier, then yes, I believe the AD9851 is suitable for your
application. If you require the AD9851 to generate the 175MHz carrier and hop
between two frequencies in this range, it's still possible to use the AD9851
but you would need to use an intermediate frequency and a PLL to mix up to the
required carrier.

I think your question really refers to the speed at which settles when you
switch between two frequencies. When you are implementing FSK in the analog
domain, the settling time (or lock time) is a key consideration since you have
to tune the analog circuit to the new frequency. In a DDS however, this is not
really an issue. You are not tuning the circuit, instead, you are adjusting the
step size of the phase accumulator.  As soon as you update the frequency word,
in the DDS the phase accumulator immediately starts to output the new frequency
( there is a latency of a few master clock cycles while the register is updates
but nothing significant).

The limitation is how fast you can update the serial or parallel interface with
the required tuning word. It should have no trouble responding to an update of
2400baud.

The AD9835 has Phase a Frequency registers on chip. You can program these
registers with the two frequencies in your FSK modulation Scheme and then use a
single pin to switch between the two output frequencies. The AD9835 is ,
however, limited to a maximum clock frequency of 50MHz.

  • ad9851
  • Share
  • History
  • More
  • Cancel
Comments
Anonymous
Related
 
社交网络
快速链接
  • 关于ADI
  • Partners
  • 模拟对话
  • 职业
  • 联系我们
  • 投资信息
  • 新闻中心
  • 质量和可靠性
  • 办事处与代理商
  • Analog Garage
语言
  • English
  • 简体中文
  • 日本語
  • Руccкий
电子快讯

欲获得最新ADI产品、设计工具、培训与活动的相关新闻与文章,请从我们的在线快讯中选出您感兴趣的产品类别,每月或每季度都会发送至您的收件箱。

订阅
Switch to mobile view
Analog Logo
© 1995 - 2022 Analog Devices, Inc. All Rights Reserved 沪ICP备09046653号-1
  • ©
  • 1995 - 2022 Analog Devices, Inc. All Rights Reserved
  • 沪ICP备09046653号-1
  • 网站地图
  • 隐私和保密政策
  • 隐私设置
  • 使用条款
 
Social
Quick Links
  • About ADI
  • Partners
  • Analog Dialogue
  • Careers
  • Contact us
  • Investor Relations
  • News Room
  • Quality & Reliability
  • Sales & Distribution
  • Analog Garage
Languages
  • English
  • 简体中文
  • 日本語
  • Руccкий
Newsletters

Interested in the latest news and articles about ADI products, design tools, training and events? Choose from one of our 12 newsletters that match your product area of interest, delivered monthly or quarterly to your inbox.

Sign Up
Switch to mobile view
Analog Logo
© 1995 - 2022 Analog Devices, Inc. All Rights Reserved 沪ICP备09046653号-1
  • ©
  • 1995 - 2022 Analog Devices, Inc. All Rights Reserved
  • 沪ICP备09046653号-1
  • Sitemap
  • Privacy & Security
  • Privacy Settings
  • Terms of use
EngineerZone Uses cookies to ensure you get the best experience in our community. For more information on cookies, please read our Privacy & Security Statement.