Thin Film Opto-Electric Transformer

A thin film optoelectric transformer consisting of a p-n junction photocell (500×500 μm²) and a multilayer spiral coil transformer (1.4×1.4 mm²), monolithically fabricated on a Si substrate, is proposed, and its fundamental characteristics are described. The optical power from a layer diode (LD) is converted into electric power by the photocell, and the photocurrent is then converted into an output voltage V_o by the miniaturized transformer. In these experiments, both the primary and the secondary coils had double layers of rectangular spiral coils and had tire same number of turns, i.e. the device was a 1:1 transformer. The frequency dependence of the inductance L of the double-layer coil with an outer core was measured. Annealed magnetic film had better characteristics for inductance than did unannealed film. Circuit simulations were performed by a PSpice simulator using experimental values for parameters; the experimental results could be explained satisfactorily by the simulation results.