Bidirectional data transfer based asynchronous VLSI system using multiple-valued current mode logic

A new asynchronous data transfer scheme using multiple-valued 2-color 1-phase coding, called a bidirectional data transfer scheme, is proposed for a high-performance and low-power VLSI system. Valid data signals of "0" or "1" are represented by binary dual-rail complementary codes, (0,1) and (1,0), and "ODD" and "EVEN" colors are represented by binary dual-rail codes, (0,0) and (1,1), respectively. Control signals from both a transmitter and a receiver are represented by dual-rail multiple-valued coding with superposition of data and color signals. The use of dual-rail coding makes it easy to detect EVEN and ODD information by calculating the sum of dual-rail codes, even when data and color information are mixed on the same wires in asynchronous data transfer Since a linear-summation can be implemented by wiring without active devices in multiple-valued bidirectional current-mode circuitry, the proposed circuit for asynchronous control becomes simple. It is evaluated in a 0.18 μm CMOS technology that the switching speed of the proposed asynchronous data transfer scheme is about 1.6-times faster than that of the corresponding binary CMOS implementation under the normalized power dissipation.