Abstract: An operational amplifier including a pair of differential input transistors is provided with a feedback resistor switching circuit and a variable current source. When a loaded optical disk is a DVD-ROM, the feedback resistor switching circuit reduces a gain of the operational amplifier and the variable current source selects a large current (of, for example, 1 mA) as a common bias current supplied to the differential input transistors. When the loaded optical disk is a DVD-RAM with low reflectance and low recording/reproducing speed, the feedback resistor switching circuit enhances the gain of the operational amplifier and the variable current source selects a small current (of, for example, 0.5 mA) as the common bias current.

Abstract: A packaging structure suitable for an integrated circuit device receiving short-wavelength laser light is provided. A lead-mounted substrate is placed on the side of the light receiving surface of the integrated circuit device having a photo detecting part. The lead is electrically connected with the integrated circuit device via an electrode. The integrated circuit device and the substrate are encapsulated with an encapsulation section. The substrate has an opening at a position above the photo detecting part.

Abstract: A packaging structure suitable for an integrated circuit device receiving short-wavelength laser light is provided. The integrated circuit device having a photo detecting part, leads and wires for connection therebetween are encapsulated in an encapsulation section. A recess is formed on the light incident surface of the encapsulation section above the photo detecting part, to thin the encapsulation section on the surface of the photo detecting part and thereby reduce the energy of light absorbed by the encapsulation section.

Abstract: A packaging structure suitable for an integrated circuit device receiving short-wavelength laser light is provided. A lead-mounted substrate is placed on the side of the light receiving surface of the integrated circuit device having a photo detecting part. The lead is electrically connected with the integrated circuit device via an electrode. The integrated circuit device and the substrate are encapsulated with an encapsulation section. The substrate has an opening at a position above the photo detecting part.

Abstract: An operational amplifier including a pair of differential input transistors is provided with a feedback resistor switching circuit and a variable current source. When a loaded optical disk is a DVD-ROM, the feedback resistor switching circuit reduces a gain of the operational amplifier and the variable current source selects a large current (of, for example, 1 mA) as a common bias current supplied to the differential input transistors. When the loaded optical disk is a DVD-RAM with low reflectance and low recording/reproducing speed, the feedback resistor switching circuit enhances the gain of the operational amplifier and the variable current source selects a small current (of, for example, 0.5 mA) as the common bias current.

Abstract: An apparatus is provided for packaging a laminated capacitor made to have a low ESL value and is used for a decoupling capacitor to be connected to a power supply circuit for a MPU chip providing a MPU. The laminated capacitor is accommodated within a cavity provided on a wiring board. The capacitor includes a plurality of first external terminal electrodes connected to first internal electrodes via a plurality of first feedthrough conductors and a plurality of second external terminal electrodes connected to second internal electrodes via a plurality of second feedthrough conductors. The first external terminal electrodes provided on a first major surface of a capacitor body are connected to via-hole conductors at the hot side for the power source within a substrate, and the second external terminal electrodes provided on first and second major surfaces are connected to grounding via-hole conductors and a mother board within the substrate.

Abstract: A passband-adjustable photo-detector for inverse photoemission spectroscopy, in which an electron beam from an electron gun is applied onto a sample and a light reflected therefrom is converged, so as to effect photo-detection, wherein said photo-detector comprises a photo-electron multiplier, a LiF monocrystal window and a CaF.sub.2 monocrystal window individually deposited with a KCl thin film in the front of a photo-electron multiplier in the photo-detector, wherein said windows means are provided for arbitrarily setting the temperature from the vicinity of liquid nitrogen temperature to the order of 150.degree. C., a photo-electron multiplier having a first dinode deposited a KCl thin film on a surface thereof said photo-electron multiplier, and an output of the photo electron multiplier is connected with a pulse counter circuit through an amplifier, so as to measure anyone selected from the group consisting of light absorption property, window transmissibility and sensitivity as a bandpass filter.

Abstract: A narrow band high sensitivity photo-detector for inverse photoemission spectroscopy, in which an electron beam from an electron gun is applied onto a sample and a light reflected therefrom is converged into a photo-electron detector, so as to effect photo-electron detection in a photo-electron multiplier, wherein said photo-electron detector comprises a CaF.sub.2 monocrystal window provided with a KCl thin film in the front of said photo-electron detector, a first dynode deposited with a KCl thin film on a surface thereof, wherein an output of the photo-electron multiplier is applied with a pulse counter circuit through an amplifier, so as to measure light absorption properties, window transmissibility and detection sensitivity as a band pass filter.

Abstract: A bandpass photon detector for inverse photoemission spectroscopy comprises a sample chamber and an analyzer chamber connected to a vacuum exhaust system, respectively; a photon detector connected to the analyzer chamber; the sample chamber and the analyzer chamber are switchably connected through a gate valve and provided with a sample transfer system for transferring a sample held at a center axial line of the sample chamber to a center portion of the analyzer chamber, the analyzer chamber is provided with an electron gun opposed to a sample positioned at a center where the sample is transferred and a photomultiplier comprising a low cut filter consisting of Cu-BeO at the opposite side of the electron gun, wherein a potassium chloride is deposited in a thickness of 500-1000 .ANG. on a first diode of said photomultiplier, thereby high inverse photoemission spectroscopy can be measured so as to analysis and estimation of semiconductors and magnetic material.