Dependence of the Propagation Delay of an ECL Gate on the Transistor and Circuit Parameters

The propagation delay T of an Emitter-Coupled-Logic (ECL) gate is studied as a function of the different device aind circuit. parameters involved. It is found that the delay in the response of the switching transistor is the dominant delay component. The propagation delay is highly sensitive to the change in the cut-off frequency and the magnitude of the current source. This sensitivity is, however, a strong function of the range in which these parameters are considered. The delay is also highly but monotically sensitive to the product of the base resistance with the collector junction capacitance. The results show a weaker sensitivity of the propagation delay to the voltage swing, to the collector to substrate capacitance and to the emitter junction capacitance. Finally, the delay is almost insensitive to the emitter resistance and to the current gain.