Analytic transient solution of SCFL logic gates

Abstract

In this paper we propose the analytical solution of switching transients for SCFL logic gates. The analysis of an SCFL logic gate is carried out without linearization and can be brought back to multiple analyses of a basic cell, given by a differential pair with switching input voltages and a variable tail current, to take the effect of series-gating into account. The differential equation for this cell is a Riccati equation, if a quadratic current–voltage relationship is used for the transistors, and it can be solved by the infinite power series method, in case of polynomial input signals. An algorithm is proposed to analyse the full transient of a complex SCFL gate. This provides a closed form expression for transient signals in terms of circuit and device parameters, that can be used for symbolic analysis or fast time-domain numerical simulation. Some case studies are presented for SCFL gates using OMMIC ED02AH technology, and a good agreement between the proposed model and SPICE simulations using complex device models is obtained. Copyright © 2005 John Wiley & Sons, Ltd.