  In Carry Propagate Adders, carry propagation is the critical delay. The most
efficient scheme is to generate Cout0 (Cin=0) and Cout1(Cin=1) and multiplex
the correct output according to Cin. For any radix, the carry output is always
0/1. We present two versions of ternary adders with Cin = (0V, Vdd/2) and Cin =
(0V, Vdd) and two versions of quaternary adders with Cin = (0V, Vdd/3) and Cin
= (0V, Vdd). Using full swing Vdd for Cin reduces the propagation delays for
ternary and quaternary adders. 6-bit, 4-trit and 3-quit CPAs are then compared.
