IC voltage doubler and oscillator

[malizevzek]

I'm designing an integrated voltage doubler. The power is in the range of 20 uW. The supply voltage is approx. 2 times bigger than Vth. Since I use integrated capacitors, I have ~20% of parasitics associated with them. The other losses stem from parasitics of MOSFET switches. I use a non-overlapping clock.
Four questions:
:arrow: I get considerably more losses then estimated. Can the reverse conduction in output transistor be responsible?
:arrow: Since the frequency deviation of an ring-oscillator (inverter-based) is to big, do I have to do a voltage-controlled version of it?
:arrow: Has anyone experience with MCML oscillators?
:arrow: In general, what are the possibilities when an integrated oscillator is needed?

 

[carlson]

parasitic capacitance make a great effect. and the reverse conduction also have the effect.