The layout of the PCB should be obtained as a
tradeoff between compactness and the need for avoiding parasitic
coupling among wires of the circuit. The use of SMD components
makes the circuit more compact but requires a particular
care for the layout design. Finally the gain of the CM current
estimator is a critical parameter: it should be as high as possible
without causing oscillations. In the prototype realization it has been obtained by a variable resistance set manually to
compensate possible tolerance of other circuit components