Non overlapping Clock generator

The design of this pulse oximeter called for a two phase non overlapping clock. Initially, our design had called for a simple oscillator circuit with an inverter. We found that the both clocks could be high at the same time presenting problems in demodulation for dual channels.

Therefore a non-overlapping clock had to be implemented. Initially I was going to use a 555 timer but I had difficulties finding resources on how to implement non overlapping clock. Non overlapping clock is very common in digital circuit so I found some resources from my Rababey book. It's often used for charge pumping and evaluate circuits.

http://books.google.com/books?id=vxGO4_B98gsC&pg=PA103&lpg=PA103&dq=non+overlapping+clock+nand&source=bl&ots=4k8qTqHc4v&sig=Pe_qcwaTse9pUWvxxnl4285c4W8&hl=en&ei=7OD5S9KCDIO8M93o7YMI&sa=X&oi=book_result&ct=result&resnum=6&ved=0CDEQ6AEwBQ#v=onepage&q=non%20overlapping%20clock%20nand&f=false

I have attached an image of the schematic and the resulting simulation. I built and tested this on the breadboard and had success. I was able to verify that with this design the clocks are indeed non overlapping. This week we will build an external circuit which will do this and can hook in with the POX board. Jon will update with progress on this front later this week.