Patent ID: 8120925

Claim:
A circuit device comprising: an optical circuit including an optical substrate having an electro-optical effect, the optical substrate including an optical wave guide and a progressive wave electrode; and an electrical circuit including: a dielectric substrate including a first face and a second face opposite side of the first face; a coplanar line including a first line, a second line and ground electrodes, the first line and the second line being decoupled mutually, the ground electrodes being formed around the first line and the second line, the first line, the second line and the ground electrodes being formed on the first face of the dielectric substrate; a capacitor for connecting the first line and the second line; a termination resistor connecting the second line; a microstrip line formed on the second face of the dielectric substrate; and a conducting portion formed in the dielectric substrate and electrically connecting the first line and the microstrip line, wherein the first line is coupled to the progressive wave electrode for terminating a signal for modulating an optical signal that propagates through the optical wave guide and for providing a DC bias signal.