How to get a DC vaule from high speed differential CML ckt?

[eegchen]

hi,
I have a differential CML Buffer with resistance as load. It runs at 20G/Hz.

What's the reasonable way to get the DC value for one output ?

Best Wishes
Gang

 

[rfmw]

Re: How to get a DC vaule from high speed differential CML c

Would you explain some more on your problem?

 

[eegchen]

Re: How to get a DC vaule from high speed differential CML c

I have differential current mode logic (CML)buffer with resistance load. THe input frequency is 20GHz and the output swing is 400mv from VDD to "VDD-400mv". it's a typical cml swing.

So the 20GHz input frequency go through the CML buffer, i get a 20GHz output frequency with swing from VDD to "VDD-400mV". I wanna know how to get the buffer ouput' DC value. Ideally, it should be VDD-200mv. correct ?

Would you explain some more on your problem?

 

[rfmw]

Re: How to get a DC vaule from high speed differential CML c

That's correct for a 50% duty cycle, yes.

 

[eegchen]

Re: How to get a DC vaule from high speed differential CML c

Thanks， what am i concerning is how to get it. Now i just pass the output go through a second order RC low pass filter. but it need time to be stable, also i am wondering wheather the RC load will damage the circuit, because it works so high frequency.

Is it a correct way? or is there any other way to do it?

That's correct for a 50% duty cycle, yes.