How to change a wave into a square wave?

[oliverlin09]

How to get a squre wave

Dear all,

I am wondering if there are any way to change this wave (Please see the attached file) to be a square wave.
For example, build some kind of circuits or use what kind of components???

 

[Logicdevv]

Re: How to get a squre wave

1.The circuit is working at very low frequency.
2.Signal is settling to 3.3v instead of 5v

and without component knowledge, it can not be fixed..

if you could post the circuit then I can suggest you a better solution..


cheers,
Logicdevv.co.uk

 

[oliverlin09]

Re: How to get a squre wave

Hiya,

Please see the attached file.
That is my circuit.

My input is "pulse". The signal is from FPGA.
The frequency is 10MHz.

 

[karesz]

How to get a squre wave

Hallo Oliver,
is these pls a measured signal or simulated?
Am I right that on your screen print is a 1MHz signal(or 10x magnified)!?

For me is it like a HF-measurements problem! Did you applyed some load to the IC or was the output "free"?
If you need only one half of the driver, connect the other input(Nr4) to GND...
Because you dont be better after buffering: how is your input signal quality pls?
If your measurements setup correct is and in spite of it is your input signal similar "miserable": apply pls some low pass filtering on that...
I see here a resonant part of 5.th harmonic...
K.
Did you checked these script?

 

[FvM]

Re: How to get a squre wave

Considering your second post, I don't know what you are exactly asking for?

Yes, you can "change" a considerably ringing signal to a square wave, if it still allows an unequivocal level detection.
Yes, this can be done with a comparator or a logic gate with hysteresis (schmitt trigger).The gate driver IC is a possible
example of "change to a square wave".

The ringing is however coming near to the thresholds, bringing up a risk of unintended switching events. They could
be fatal in case of a MOSFET power stage driven by this signal. We all know, that the FPGA output waveform looks different.
So bad wiring is obviously the reason for the observed problems. Signal filtering can reduce the ringing, but it would also
add a signal delay.

B.T.W, a more user friendly way to present schematics and waveforms is to convert *.bmp to a compressed format, e.g.
*.gif or *.png and attach them directly. Even windows paintbrush can do the conversion, powerful free tools as Irfanview
can perfectly.

 

[oliverlin09]

Re: How to get a squre wave

Hi karesz,

Am I right that on your screen print is a 1MHz signal(or 10x magnified)!?

My signal is 10MHz.

Did you applyed some load to the IC or was the output "free"?

I haven't put any load on the IC's output.
I read your attached file. It shows to apply a load capacitor.
Do you think if it's alright to put a 1nF capacitor for my output??

how is your input signal quality pls?

My input signal is from FPGA. I don't think the quality of the signal is good.
So I thought to use some ways to improve the output signal.

Did you checked these script?

I haven't. Thanks for your application note. I feel it's quite helpful.

Oliver

Added after 16 minutes:

Hi FvM,

Gate driver ICs. It sounds a good idea.
I will try to find a suitable gate driver IC tomorrow, and add it on my input part.

 

[karesz]

How to get a squre wave

Hi,
The IR Apll Note gave Cload as 1 nF than your FET has some similar(1-3nF) too...With them you will see maybe some edge times of 2-300nsec, but loadless at 10-20 nsec and maybe even the knowed (miserable) ringings and so on...

I can not see a connection between your scope screenprint/time scaling & 10MHz?...I can see only 1MHz.
For me is your biggest problem, that your setups/breadboards arent "(RF)CLEAN"!:-(
Sorry, but same is with your OPs & here with drivers signal quality too...
Likes you have mostly (to)long lines/wires between parts of circuits/equipments?
Sourch pls for applications notes i.e. Jim Williams by Linear Technology: RF/HF bread boardings technique/how do I measure, what are hand effects and so on_sorry I ca not remember the exact titels, but the guy is good and has much script for these problematics.
The most can you find in older Appl Handbooks too from LT...
I belief; for signal quality enhancing you must check for correct HF building/measuring techniques!
K.

 

[Logicdevv]

Re: How to get a squre wave

I will suggest to put a pullup of 5v at the output of FPGA .
let me know if you have configure the FPGA output pin other then ttl/CMOS logic..

and remove the pulldown from pulse (pinoutput of FPGA )

and put a schotty diode at the output wrt 5v and gnd.

Logicdevv.co.uk

before you ask me about 5v tolerance..

The trick is using IO elements is to tie the output pin to your 5V supply with a pullup resistor. Then when you want a logic 1, you just tristate the output and the pullup drags the pin up to 5V. When you want a logic 0, you un-tristate the output and output a logic 0.

Cheers,
Logicdevv