  We present a novel methodology to enable control of a neuromorphic circuit in
close analogy with the physiological neuromodulation of a single neuron. The
methodology is general in that it only relies on a parallel interconnection of
elementary voltage-controlled current sources. In contrast to controlling a
nonlinear circuit through the parameter tuning of a state-space model, our
approach is purely input-output. The circuit elements are controlled and
interconnected to shape the current-voltage characteristics (I-V curves) of the
circuit in prescribed timescales. In turn, shaping those I-V curves determines
the excitability properties of the circuit. We show that this methodology
enables both robust and accurate control of the circuit behavior and resembles
the biophysical mechanisms of neuromodulation. As a proof of concept, we
simulate a SPICE model composed of MOSFET transconductance amplifiers operating
in the weak inversion regime.
