[SOLVED] [URGENT]Differential to Single Ended 1-bit Quantizer

[g.s.javed]

HI,

I have designed a differential 1-bit quantizer, which is being used in a ΣΔ -ADC on chip. But there is only ONE High frequency pin/pad available to me.

How do I convert this differential signal to give me a rail-to-rail (VDD to GND) single ended signal. It is a 1-bit output.

I have tried a configuration.


The Output is as shown.
Blue and Red are the differential inputs.
Black is the single ended output.

But the swing is between .93V and 1.2V rather being rail-to-rail.

Please suggest a BETTER alternative or suggestion.

Thank you

Javed

 

[lamoun]

Hello Javed,

is this really your "differential signal"?
From the output screenshot I can see your input is not differential. Both your inputs are the same but inp is shifted by 0.6V and so it is always larger than inn.
The diff pair works as it should.

You could use just the inp and compare it with 0.9V.
It would be probably better to add a tail current source and some follow up inverters.