NEW YORK — An undergraduate team at Cooper Union college has developed a digital logic concept that has not previously been attempted by any manufacturer of microwave components.

The team, led by Bhaskar Krishnamachari and Simon Lok, showed its results last week at the 1998 IEEE Radio and Wireless Conference (Rawcon '98) in Colorado Springs, Colo. The group has defined Boolean operations in passive microwave devices that allow logic operations at speeds of 2 Gbits/second and faster.

The Cooper Union team's definition of a "NOT" function is particularly innovative, as it uses a transmission line of a length corresponding to a 180° phase shift to create a fully reversible phase shift key (PSK) logic gate. amplitude shift key (ASK) versions of NOT are realized by adding a power coupler to the phase shifter. For OR operations, dual power couplers are used for PSK systems, and a single power coupler with dual inputs is used for ASK systems.

The team fabricated 300-MHz circuits at Cooper Union to show that carrier modulation circuits with microwave logic can operate faster and more efficiently than semiconductor-based logic systems. A search of the literature showed only a limited effort in Russia in 1994 to develop microwave logic, Lok said.

Now that the team's members have graduated, they are contemplating forming a startup to continue their work in microwave Boolean operations.