Patent ID: 7545156

Claim:
A test circuit, comprising: a plurality of light-receiving elements; a plurality of amplifiers, each of which converts, into a voltage, a photoelectric current supplied from one of said plurality of light-receiving elements; a test pad to which a voltage is applied from outside; and an electric current supplier that supplies an electric current to each of said plurality of light-receiving elements and each of said plurality of amplifiers, the electric current corresponding to the voltage applied to said test pad, wherein said electric current supplier selectively supplies an electric current to a first group of light-receiving elements and to a second group of light-receiving elements, said first group of light-receiving elements including light-receiving elements, out of said plurality of light-receiving elements, which are neither vertically nor horizontally adjacent to each other, and said second group of light-receiving elements including light-receiving elements, out of said plurality of light-receiving elements, which are vertically or horizontally adjacent to said light-receiving elements of said first group of light-receiving elements, so that; each amplifier, out of said plurality of amplifiers, which converts a photoelectric current supplied from one light-receiving element included in one of said first group of light-receiving elements and said second group of light-receiving elements to which the electric current is supplied outputs a voltage to determine whether said amplifier is operating properly, and each amplifier, out of said plurality of amplifiers, that convert a photoelectric current supplied from one light-receiving element included in one of said first group of light-receiving elements and said second group of light-receiving elements to which the electric current is not supplied outputs a voltage to determine whether a leak current flows between said plurality of light-receiving elements.