Differential Non-Uniform Downsized Distributed Amplifier

Distributed circuits using transmission lines (T-lines) or inductors exhibit high gain-bandwidth-products (GBW), as required by broadband communication systems. In this paper, the design of non-uniform downsized distributed amplifiers (DAs) is explored. Conventional DAs employ a topology in which inductors or T-lines separate the gain stages, yet the output currents from individual stages combine additively [1]. Major sources of performance degradation in any DA are the non-zero frequencydependent loss of the inductors and the non-zero output conductance of the gain stages, which in turn decrease gain and BW. Previous works on distributed circuits do not consider the effect of inductor loss and output conductances of the constituent gain stages on the DA topology, leading us to an important question: Considering non-zero circuit losses, does a conventional DA with an optimum number of identical gain stages and segmental inductors achieve maximum GBW and better noise performance? To answer this question, mechanisms that affect gain and BW of conventional distributed circuits are studied, while non-zero losses are considered.