Elektro-optische logische Schaltung

1,118,826. Semi - conductor. TEXAS INSTRUMENTS Inc. 14 June, 1965 [29 June, 1964], No. 25138/65. Heading H3T. [Also in Divisions G1 and H1] In an opto-electronic coupling system the detector and a subsequent semi-conductor device to which its output is delivered are integrated in a single substrate. An integrated circuit comprises a plurality of interconnected components in a body of semi-conductor material, the photo-sensitive detector having at least two regions of opposite conductivity types separated by a rectifying junction, and means are provided for generating optical radiation (including infra-red) directed on the photo-sensitive detector and having a wavelength such that at least a portion of the radiation is absorbed by the photo-sensitive detector to generate charge carriers which are collected at the rectifying junction. A wide-band amplifier, Fig. 17, includes a diode detector connected between base and ground of a transistor 60 which arrangement overcomes difficulties arising from the mal collection of charge carriers at the rectifying junction (42), Fig. 4 (not shown), and a resistor 111 to limit the base current to a value less than the photo-current generated by the diode in response to light from a signalling source 2 which may be gallium-arsenide. An additional transistor which may be N.P.N. or P.N.P. 64 connected in the Darlington configuration is provided to increase amplification and eliminate the Miller effect, the transistor not cutting off and on but having its degree of conduction changed by the detected light. Negative feed-back is provided between the collector of transistor 64 and the base of transistor 60, and between the collector of transistor 80 and the collector of transistor 64 through a transistor 72, the latter feed-back circuit including transistor 130. The feed-back to transistor 60 enables the value of resistor 111 to be considerably reduced in value and thus in size, and the feed-back to transistor 64 via transistors 130 and 72 holds the collector potential, and thus the base value of transistor 80, at a value preventing saturation of the transistor 80. A resistor 140 between the base of transistor 130 and the collector of transistor 72 prevents the charging of the Miller capacitance in transistor 130. The resistor 111 which is formed by a path in the silicon body base produces distortion at high frequencies due to its distributed capacity and the distortion is eliminated by the inclusion of capacitor 114 in the fee