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Design >> Analog Design >> Analog delay
https://designers-guide.org/forum/YaBB.pl?num=1411297031

Message started by Lo on Sep 21^st, 2014, 3:57am

Title: Analog delay
Post by Lo on Sep 21^st, 2014, 3:57am

I am trying to build a simple ciruit to delay an FMCW signal (frequency range of [1-10] Ghz) with mutiple of 50 pico second (ps). A bank of delays with mutiple of 50 ps, i.e., 50 ps, 100 ps, 150 ps, ...,.

Any suggestion preferebly with RFIC,MMIC, or even other discrete componenets highly apprecited!
Lo

Title: Re: Analog delay
Post by aaron_do on Sep 21^st, 2014, 6:45pm

Hi,

Is your signal a broadband signal (1-10GHz)? Are you working at board level? Does the delay need to be constant across frequency (what range?). How accurate does it need to be?

Off the top of my head, you could look into using transmission lines which bend back and SPNT switches to choose the delay. The lines will be quite long, but I think the delay should be quite frequency independent. You can also look into designing RLC all-pass filters (again with SPNT to switch between them). If it were on chip you could look into delay-locked loops or even just banks of inverters.

regards,
Aaron

Title: Re: Analog delay
Post by loose-electron on Sep 22^nd, 2014, 11:26am

The signal they are trying to delay (FMCW???) I am guessing is a continuous wave frequency modulated signal, but it would be useful to know if it is logic edges they are trying to delay or some signal where the phase relationship of the harmonics are important to preserve. Depending on that little peice of information, the methods to use are totally different things.

Title: Re: Analog delay
Post by Lo on Sep 27^th, 2014, 2:28pm

Hi Aaron,

The signal is a chirp signal sweeping few GHz bandwidth. We work at board level and the delay doesn't need to be constant across frequency but adjustable in some steps for a certain range.
An accuracy below 20-50 ps is sufficient!

Thanks for the hints,
Lo

Title: Re: Analog delay
Post by Lo on Sep 27^th, 2014, 2:31pm

Hi Loose-electron,

Your guess is perfectly correct and the phase relationship of the harmonics are is required to be preserved.

Thanks for the reply,
Lo

Title: Re: Analog delay
Post by loose-electron on Sep 29^th, 2014, 9:11pm

what you are looking for is commonly called an electromagnetic delay line.

some are available as components off the shelf, or you can fashion your own using LC networks.

Time to go do some component research.

See:

http://www.allenavionics.com/Info_Srv/SpecifyingDelayLinesPage3.htm

http://www.digikey.com/product-search/en/inductors-coils-chokes/delay-lines/197808?k=delay%20line

DigiKey can probably provide what you need.

Title: Re: Analog delay
Post by Lo on Oct 3^rd, 2014, 1:16pm

Great, thanks!
Lo