Please recommend proper comparator part for Zero crossing Detector at RF Frequency ( 600 MhZ ~ 1 GHz )

Hi,

What is the amplitude of your input signal? Will you be using single supply or dual supply?

What is this application specifically for? The LMH7322 is a high speed device that can operate for that frequency range.

Regards,
Jonny

     Thanks a lot for your speed reply and recommendation of LMH7322.

1. amplitude of input signal : sine wave through signal generator 6062.

2. I will use single supply.

3. application  : time mark generator

   I expect your advice on a circuit diagram using LMH7322 and values of parts( resistor etc,..) and the names of the parts.

 Best Regards,

 P. Dary

Hi there...

So you have stated that you are a beginner, but know in general that you need some resistors/diodes to generate a clean ZCD so that's a good start...

Instead of me just giving you the values and names of parts that you need, I think it would be much more useful and helpful for you if you try to understand the whole design process of a ZCD.

Let's start off with some basics... Where and why is a diode needed in a ZCD? If you include a schematic diagram of the idea you have for this circuit, it would be very helpful for me to gauge the level you are at and where specifically it seems you need help.

Also again for the amplitude of the input signal, it would be very helpful for me if you gave a specific peak to peak amplitude you plan on applying to the device.

Best Regards,
Jonny

I have looked at the circuit diagram of TLV7011 performing ZCD function.
and the two resistors and zenor diode are included on the circuit.
Is the type using the two resistors and zenor diode wrong in case of LMH7322 ?
The complex device and parts composing the circuit diagram of LMH7322 confuse me as a beginner.
I lack technical knowledge on ZCD prefer simple circuit such as the case of TLV7011.

Concerning  AMPLITUDE of input signal, I didn't study on it and so prepare it yet.
 
Best Regards,
P. Dary

Hi,

There are several different ways to make a zero cross detect, and the one included with the 7011 is a very simple one.

You can use this circuit on the LMH7322 to create a Zero Cross Detect, however you would need to know the amplitude of your input signal to be able to calculate the correct voltage divider ratio for the resistors to be within the common mode input of the LMH7322.

Regards,
Jonny

 Hi.

Thanks a lot for your mentoring.


I intend to use the signal generator made in Giga-Tronics Inc.; model name : 6062A.

I can control the value of input signal voltage by using Function button " Amplitude ; MHz/ V" arranged on 6062A.

For example, I can input the correct value of signal voltage whatever value is input voltage " as shown on datasheet of LMH7322.

Could you please tell me how many input signal voltage should be input to IN+ of LMH7322 with IN- connected to GROUND?


I am looking forward to hearing you.



Happy New Year !!!



With Best Regards,

P. dary

Hi,

The info for the max input voltage you can apply to the LMH7322 is listed in the datasheet (VEE [Ground in your case] up to 1.5V less than what the device is powered on with).

When you have IN- connected to ground, you are using a non-inverting output. Ground (0V) will be your reference, so whenever VIN > 0, OUT = HIGH, VIN < 0, OUT = LOW.

It looks like you don't quite understand the fundamentals of comparators, I would highly suggest you look at some of our Video Training Series on comparators. This will be a good way for you to get a good understanding of comparator circuits and might even help you figure out how to make your ZCD :) --> training.ti.com/ti-precision-labs-op-amps-comparator-applications-1

There are 4 training videos in the series, so be sure to check all of them out and come back here if you have any questions. For now, I will be closing this thread.

Regards,
Jonny