how to Design a ring oscillator with only 10mV swing?

Why should we?

Can you take it as a chanllenge question?
thanks

Yes, but personally, I'm not very motivated by abstract challenges.
Apart from the design purpose, what's the intended technology? CMOS? What's the supply voltage?

The supply voltage is 3V.

I do not know the technology

I kind of think it is probably to use bipolar devices. But both CMOS and bipolar can be used for this question.
Any ideas?
thanks

Yes you could design a full-swing ring oscillator and use a resistive divider at the output for reducing the swing size.

Also you can use OpAmp for volatge divider.