A novel multiply-by-three circuit

Recently, while considering the connection of a 48 bit word computer to a 16 bit computer, we felt the need for a fast and inexpensive device that would multiply a binary address by a factor of three. Since 3N = N + 2N, there is an obvious solution of providing a normal adder circuit and presenting one set of inputs with N and the other with N-shifted left one place. But, there is a great deal of redundancy here since knowing one input we have complete knowledge of the other.