A question about to convert a sine wave to a square wave

[txzzc1982]

Dear all,

I am currently designing a sine to square wave converter at 10MHz, but also a frequency converter from 10MHz to 40MHz. Actually, I'd like to have a 40MHz clock with 50% duty cycle to my ADC for sampling at intermediate frequency. I have already had a oscillator produced a stable 10MHz sinusoidal wave. So, I should convert it to square wave first, then to up-convert the frequency to 40MHz that I expected to have.

Do you have any idea for it? Do you think I have to design it by myself, or to use a factory product? If there is a product that can realize this function from a 10MHz sinusoidal wave to a 40MHz square wave, I prefer to use it.

You may have related design experience. I hope you guys could help me. I'll appriciate it!

Thanks,
Cheng

 

[cdh7]

Hi,

The simplest way to convert a sine wave to a square wave is to use a Schmitt trigger buffer or inverter. Just make sure to correctly bias and scale your input sine wave.

As for frequency conversion, a PLL is the usual way. If you want something quick without the trouble of designing a PLL, maybe you can use two frequency doublers in series. See this thread for an example:

If you want a stable clock for your ADC, why not just get a 40 MHz crystal oscillator?

Regards,
Chris

 

[karesz]

Hi,
For ADC Clk (becouse they need usual 50+/-5% duty) I would design with a "clock circuit", they has on chip PLL, some are "delay less" too...
You can find such ICs from National,fFairchild, nxp, Quality Semi, one (some older) examplar is: QS5V993A has 40 MHz from 10MHz in, you has 4x Outputs, with programmable phases...
If you likes/needs exactly 50% duty to produce (& dont become QS5V like ICs); a relative simple way is to make 80MHz & divide it by 2 (FF)= a garantied 50% pulse output
Good luck!
K.

Added after 10 minutes:

I learnd; Quality Semi is yet IDT...
w*w.qualitysemi.com/?app=search&searchType=parametric&catID=58697
i.e.:74FCT388915T

 

[txzzc1982]

Hi,

The simplest way to convert a sine wave to a square wave is to use a Schmitt trigger buffer or inverter. Just make sure to correctly bias and scale your input sine wave.

As for frequency conversion, a PLL is the usual way. If you want something quick without the trouble of designing a PLL, maybe you can use two frequency doublers in series. See this thread for an example:

If you want a stable clock for your ADC, why not just get a 40 MHz crystal oscillator?

Regards,
Chris

Actually, I have a assembled box in which a 10MHz oscillator inside as well as other functions that I need in my system. So, I have to use it.
I like your suggestion to double the frequency twice.
Thanks!

Added after 1 minutes:

Hi,
For ADC Clk (becouse they need usual 50+/-5% duty) I would design with a "clock circuit", they has on chip PLL, some are "delay less" too...
You can find such ICs from National,fFairchild, nxp, Quality Semi, one (some older) examplar is: QS5V993A has 40 MHz from 10MHz in, you has 4x Outputs, with programmable phases...
If you likes/needs exactly 50% duty to produce (& dont become QS5V like ICs); a relative simple way is to make 80MHz & divide it by 2 (FF)= a garantied 50% pulse output
Good luck!
K.

Added after 10 minutes:

I learnd; Quality Semi is yet IDT...
w*w.qualitysemi.com/?app=search&searchType=parametric&catID=58697
i.e.:74FCT388915T

Hm...good idea! That's really what I expected to look for. Thank you!!
I'll check and study it...