Nanoamp current oscillator?

[Artlav]

Greetings.

Is it possible to make a square wave oscillator that would draw less than 4µA (better yet tens of nA), work from 1 to 5V, at some frequency between 30Hz and low kHz?

Attiny13 microprocessor does the job at 4µA, doing 30Hz.
The best flip-flop that is stable consumes about 6µA, doing 50Hz.

How to do better?

 

[erikl]

See e.g. this paper with the comparison table and references on the last page.