Design Theory of Optimum Negative-Resistance Amplifiers

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 ∣ S21∣ < ½(1+eπGD/ω0CD), where ω0 is the angular bandwidth. For arbitrary passive imbedding, ∣S21∣ < eπGD/π0CD. 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.