Patent attributes
A flexible printed circuit board includes: a signal wiring pattern including: a transmission line for connecting an end of an optical device with an end of a signal generation circuit; and another transmission line for connecting another end of the optical device with another end of the signal generation circuit; a thin film resistor layer formed in a region including a region facing the signal wiring pattern so as to constitute a first microstrip line together with each of the transmission lines; a ground conductor formed in a region except a part of a region facing the thin film resistor layer within a region including a region facing the signal wiring pattern so as to constitute a second microstrip line together with each of the transmission lines; and an insulating layer formed between each two of the signal wiring pattern, the thin film resistor layer, and the ground conductor.