AbstractIn this article we present a modified least‐squares boundary residual (LSBR) method for the rigorous analysis of microwave integrated circuits (MICs). The method is relatively convergent and a semianalytical relative convergence criterion is found to be very important in optimizing its convergence. Moreover, the problem of the poor conditioning of the least‐squares matrices has been rigorously resolved. © 1992 John Wiley & Sons, Inc.