A noninvasive physiological sensor for measuring one or more physiological parameters of a medical patient can include a bump interposed between a light source and a photodetector. A tendency toward thyristor-like behavior of the multilayer semiconductor arrangements with the three bipolar transistors is suppressed with the aid of a heterojunction. An inductance having a connectable node is connected between the first and second inputs, the connectable node being symmetrically connected between the first and second inputs.