This paper yields process of development, numerical analysis, lumped circuit modeling, and experimental verification of a new hyperchaotic oscillator based on the fundamental topology of two-stage amplifier. Analyzed network structure contains two generalized bipolar transistors connected with common emitter. Both transistors are initially modeled as two-ports via full admittance matrix, considering linear backward trans-conductance and polynomial forward trans-conductance. As proved in paper, these two scalar nonlinearities can push amplifier to exhibit robust hyperchaotic behavior with significantly high Kaplan-Yorke dimension. Regions of chaos and hyperchaos in a space of admittance parameters associated with both transistors are specified following the concept of positive values of Lyapunov exponents. Long time structural stability of generated hyperchaotic waveforms is proved by construction of flow-equivalent electronic circuit and experimental measurement, that is by screenshots captured by oscilloscope.