Design a frequency synthesizer (PLL)

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Discussion Overview

The discussion centers around the design of a frequency synthesizer, specifically a phase-locked loop (PLL) type, with an output range from 1 kHz to 30 kHz. Participants explore various aspects of synthesizer design, including step sizes and types of synthesizers.

Discussion Character

  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant expresses a need for a frequency synthesizer with a specific output frequency range and complexity, indicating that existing resources are too complex.
  • Another participant suggests designing the process and finding the transfer function, implying that a filter may be necessary if output frequencies are incorrect.
  • The original poster clarifies that they require a synthesizer that outputs specific frequencies, particularly around 25 kHz, and mentions different types of synthesizers, including PLL and direct digital synthesis (DDS).
  • A participant questions the required step size for frequency adjustments, asking if steps of 1 kHz or smaller are needed.
  • The original poster specifies a need for 1 kHz step sizes, particularly for frequencies of 24.5 kHz, 25 kHz, and 26.5 kHz.
  • Another participant points out that the specified frequencies imply a step size of 500 Hz, seeking clarification on whether those are the only required frequencies.
  • The original poster reiterates the need for frequencies up to 30 kHz.
  • A later reply emphasizes the importance of understanding how frequency synthesizers work and suggests reading an introductory article, while also stating that they will not complete the design project for the original poster.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the design specifics, including the required step sizes and types of synthesizers. Multiple viewpoints on the approach to synthesizer design remain present.

Contextual Notes

There are limitations regarding the clarity of requirements for the synthesizer design, including the exact specifications for frequency steps and the types of synthesizers that may be suitable.

Eng.SAM
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Hi all, I hope u all fine and in a good health

I need to design a frequency synthesizer (PLL) with an output rage from 1KHz-30KHz, I google this bt I found a lot more complex circuits to design, so I hope u guys can help...

Thanks in advance
SAM
 
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Eng.SAM said:
Hi all, I hope u all fine and in a good health

I need to design a frequency synthesizer (PLL) with an output rage from 1KHz-30KHz, I google this bt I found a lot more complex circuits to design, so I hope u guys can help...

Thanks in advance
SAM

Sounds like you need a filter. I would design the process, come up with the transfer function and find the output frequencies. If your frequencies are off than throw in a filter with the correct transfer function.
 
Thanks man for ur replay, but I don' need afilter I need some frequency synthesizer, it's input will be any frequency, but the output is so important to be around 25 KHz.

There are types for frequency synthesizers:

Phased locked loop based synthesizer (PLL) which is easy to implement than other types.

Direct digetal synthesis (DDS), ...

so I hope you can help me with that...

Thanks in advance
SAM
 
As a minimum, you would need to know what size steps you need.

So, if it went 1000 Hz, 2000 Hz, 3000 Hz ... 30000 Hz in steps would that be OK?

Or, would you want it to be set in 1 Hz steps? So, 1000 Hz, 1001 Hz, etc?
 
I need a step size of 1KHz, since I'll use the freuencies 24.5, 25, 26.5
 
That would be steps of 500 Hz.

Are they the only frequencies you need? 24.5, 25, 26.5 ?
 
Thanks a lot, but I need the frequencies until 30khz ....
 
Eng.SAM said:
Thanks a lot, but I need the frequencies until 30khz ....

So tell us how frequency synthesizers work. We will not do your school design project for you. Read this intro article, and ask us specific questions if you have them.

http://en.wikipedia.org/wiki/Frequency_synthesizer

.
 

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