A miniature opto-electric transformer

A miniature opto-electric transformer (MOET), which consists of a monolithically fabricated p-n junction photocell and a miniaturized multilayer transformer with spiral coils on a Si chip, is proposed and demonstrated. The photocell is directly illuminated by a laser diode (LD) of 83 nm wavelength driven by an on-off signal of frequency up to 10 MHz, and the corresponding output voltage of the transformer with a turns ratio of 1:1 (the primary and the secondary coil each have 19 turns) is measured. A simplified model for the inductance L of the double layer spiral coil with an outer core is proposed and found to compare well with the experimental value. The stray capacitance and the coil resistance are also evaluated. The equivalence circuit of the MOET is shown and circuit simulations performed by the PSpice simulator are presented. Good agreement between experimental results and simulations is found