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In this paper we consider general amplifiers obtained by imbedding a linear active 1-port device in arbitrary 3-ports. The active device is assumed to have a representation of a negative conductance -GD in parallel with a parasitic capacitance CD. We prove that for the lossless reciprocal imbedding, the transducer voltage gain is limited by Â¿ S21Â¿ < Â¿(1+eÂ¿GD/Â¿0CD), where Â¿0 is the angular bandwidth. For arbitrary passive imbedding, Â¿S21Â¿ Â¿ eÂ¿GD/Â¿0CD. Synthesis methods to approach or achieve the optimum are presented. Other types of amplifier configurations are next considered. In each case, the optimum gain-bandwidth formula, synthesis procedure and some useful design curves are given.