Patent ID: 6850546

Claim:
A circuit adapted to be responsive to an AC input signal and a DC power supply voltage comprising a transistor having a control electrode adapted to be connected to the AC input signal and a variable impedance between first and second electrodes controlled by the value of the AC input signal, a laser diode connected between a DC power supply terminal adapted to be connected to the DC power supply voltage and the second electrode, the second electrode having a relatively high output impedance and a reactive component at a frequency of the AC input signal, the diode having an electrode with a relatively low input impedance coupled to the second electrode and a reactive component at the frequency of the AC input, resonances being caused by the differences in the high output impedance and low input impedance and the reactive impedances, and a negative feedback arrangement between the second electrode and control electrode for minimizing the effects of the resonances, the feedback arrangement including an amplifier for reversing the polarity of the voltages at the second electrode as coupled to the control electrode.