I need help in designing a CMOS Relaxation Oscillator ....

Hi!!! I need help in designing a CMOS Relaxation Oscillator with threshold detector. It should be able to generate 1 MHz for 1 uA and with threshold levels between 1.5v and 3.5v.
how can I evaluate f=F(i) and What kind of a circuit do you think I need for this application. I was thinking of maybe a differential amplifier followed by an inverter (for the threshold detector). What amount of gain do I need to set for the diff amp incase I select that :?
....thank you...

What do you mean "relaxation oscillator"? Do you want a sine wave or square wave output? What threshold do you want to detect? Once the problem is defined, the solution is simple.