Composite operational amplifiers: Generation and finite-gain applications

A practical and effective general approach is presented for extending the useful operating frequencies and improving the performance of linear active networks realized using operational amplifiers (OA's). This is achieved by replacing each OA in the active network by a composite operational amplifier (CNOA) constructed using
N
OA's. The technique of generating the CNOA's for any given
N
is proposed. The realizations employing the CNOA are examined according to a stringent performance criterion satisfying such important properties as extended bandwidth, stability with one- and two-pole OA models, low sensitivity to the components and OA mismatch, and wide dynamic range. Several families of CNOA's, for
N = 2, 3,
and
4
, are shown to satisfy ,the suggested performance criterion. In this contribution, the CNOA's applications in inverting, noninverting, and differential finite-gain amplifiers are given and shown theoretically and experimentally to compare favorably with the state-of-the-art realizations using the same number of OA's. Applications of the CNOA in inverting integrator and active filter realizations are presented in a companion contribution [32].