  We consider the design of a new class of passive iFIR controllers given by
the parallel action of an integrator and a finite impulse response filter.
iFIRs are more expressive than PID controllers but retain their features and
simplicity. The paper provides a model-free data-driven design for passive iFIR
controllers based on virtual reference feedback tuning. Passivity is enforced
through constrained optimization (three different formulations are discussed).
The proposed design does not rely on large datasets or accurate plant models.
