Re: sine wave as Sampling clock

dkumar wrote:
HI all,

I am trying to explore the effect of using sine wave clock from sampling
instead of conventional square wave. I understand that the major problem
will be due to slow rise time of sine wave as compared to square wave but
at high frequency sine wave still has sufficiently good rise time. Or may
be we can make the slew rate of both sine and square wave same.

All this apart, i have following questions:
1) at high frequency sampling clock , so we conventionally use sine wave
or square wave? As i feel , at high frequency sine wave is same as square
wave.

2)what is the state of the art technique of sampling for high frequency?

thanks


You need a reply without the insult appended.

0) By definition a true square wave has an infinite slew rate. What passes for "square" gets awfully round at high frequencies, though.

1) At very high frequencies it's difficult to maintain squareness to a signal, because of all the higher-yet harmonics that must be maintained.

2) I dunno. But the basic principal that you can't lose sight of is in the name -- sampling. The longer the on-time of the switch compared to the off-time the less sampling you're doing and the more mixing. At some point (possibly when all you have available is sine waves) you should probably consider downconversion with a regular ol' mixer, followed by real sampling, if necessary.

2a) Generating a squared-up sampling clock in a _very_ local part of your board from a sine wave may make sense, if you've got some really good board to use (i.e. not FR-4 at the GHz frequencies you mention elsewhere) and power to burn in the conversion.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
.

Relevant Pages

  • Re: square to sine
    ... >>> Assuming you want the sine wave to be the same frequency as the ... >>> filter tuned to the square wave's fundamental frequency. ... It would be a sine wave, if the input was a true square wave ... lowpass with high Q giving a peak at 1 kHz. ...
    (sci.electronics.basics)
  • STUPIDENT
    ... I am trying to explore the effect of using sine wave clock from sampling ... instead of conventional square wave. ... at high frequency sine wave still has sufficiently good rise time. ...
    (comp.dsp)
  • sine wave as Sampling clock
    ... I am trying to explore the effect of using sine wave clock from sampling ... instead of conventional square wave. ... at high frequency sine wave still has sufficiently good rise time. ...
    (comp.dsp)
  • Re: sine wave as sampling clock
    ... at high frequency sampling clock, so we conventionally use sine wave or square wave? ... at high frequency sine wave is same as square wave. ...
    (comp.soft-sys.matlab)
  • Re: UPS sine wave vs square wave output?
    ... A square wave input of the same RMS value of an equivalent sine wave will ... that peak DC at the filters will be 1.4 times the sine RMS ... With a stepped square wave, or worse still, a pure square wave input of the ...
    (sci.electronics.design)