Influence of the bias supply lines on the performance of RSFQ circuits

Two effects of the bias supply line on the performance of RSFQ circuits have been studied: inductive coupling between the bias supply line and circuit inductances; effect of the mirrored current in the ground plane. The following results of the study are presented: 3D calculations and experimental measurements of inductive coupling between parallel and perpendicular microstrips in presence of one and two ground planes; calculated margins dependence on the external magnetic field in RSFQ cell. Bias current density extraction method has been developed and implemented in RSFQ circuit design flow.

I. Introduction

This paper presents results of a study of the bias supply lines' influence on performance of large-scale integrated (LSI) RSFQ circuits. In these circuits DC supply lines carry high currents (hundreds of mA) and significantly influence the overall performance of the device by inducing magnetic flux into the cells and by producing mirrored current in the ground plane.