After I had build my 4 wide 1 tick carry propagation adder I challenged my self to build a 2 wide one. And this is the result. This one is slightly slower, which allowed me to make it more compact and stackable for 2 bits in a 4 wide area. The 1 tick propagation still relies on the fact that I both calculate the normal and the inverted carry out, using the normal and the inverted carry in. However the logic involving only the inputs A and B have been made smaller, but slower and the occasionally repeater had to be used to prevent wires from crossing.

The logic I used to build this circuit is:

The longest calculation time would be N+7, were N stands for the number of bits of the adder. So always 4 ticks slower that the 4 wide desgin, due to the fact that I used two XNOR gates after each other including some extra repeaters to prevent crossing wires. This design is 20 blocks long and 11 blocks high.

In the download I have added the 4 wide, 2 bit repeatable building block, however it does contain two torches which should connect to blocks on the other side of the of an repeating building block. Therefore I have also included a working 16 bit version of this design.