Development of an ECL gate with a 300 ps propagation delay

A beam-lead sealed-junction silicon air-isolated-monolithic (AIM) ECL logic gate is described which has propagation delays of as little as 250 picoseconds. The basic building block of the circuit is a 6 GHz silicon microwave transistor with an fmaxof 10 GHz. The transistors have 2.5 micron stripes and 2.5 micron spacings with a base width of 0.15 to 0.2 micron. Computer simulations of several popular isolation techniques show that the minimization of parasitics achieved with the AIM technology is necessary to achieve these speeds. The analytically predicted characteristics include a dc transfer slope of 5.1 and the following propagation delays: NOR turn-on: 300 ps, NOR turn-off: 250 ps, OR turn-on: 300ps, and OR turn-off: 410 ps. The differences in the propagation delays are caused by current-source modulation.