Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Hitachi Microcomputer Engineering, Ltd.

Takao Yaginuma

Masanori Takata

Susumu Murakami

Eiki Kondoh

Hiroshi Kozaka

Naofumi Kohno

Atsushi Hasegawa

Shigeki Morinaga

Kenichi Onda

Ikuya Kawasaki

Yasuo Matsuda

Kazuhiko Iwasaki

Tsuneo Funabashi

Takeshi Asai

Hideo Inayoshi

Kouichi Mizuta

A semiconductor rectifying diode includes a first semiconductor region of one conductivity type, a plurality of third semiconductor regions of the other conductivity type provided on one surface of said first semiconductor region to be spaced a distance W, and a main electrode provided on said one main surface to in ohmic contact with said first semiconductor region and in contact with said third semiconductor regions through the Schottky barrier. To reduce reverse leakage current a relation of 2wo&lt;W.ltoreq.3D is satisfied, where D is the depth of said third semiconductor regions and wo is the width of a depletion layer spread to said first semiconductor region by a diffusion potential of the pn junction formed between said first semiconductor region and said third semiconductor region.

Semiconductor rectifying diode with PN geometry

In order to provide miniaturization and increased-frequency operation of a DC-DC converter used with a computer, etc., a capacitor is connected in parallel with a switching element when the switching element is turned off to reduce turn-off loss. When the switching element is turned on, the capacitor and a DC power source are connected in series to supply the energy stored in the capacitor to a load circuit to result in a high initial voltage being applied across the load circuit.

DC-DC converter and a computer using the converter

A semiconductor rectifying diode includes a first semiconductor region of one conductivity type, a plurality of third semiconductor regions of the other conductivity type provided on one surface of said first semiconductor region to be spaced a distance W, and a main electrode provided on said one main surface in ohmic contact with said first semiconductor region and in contact with said third semiconductor regions through the Schottky barrier. To reduce reverse leakage current a relation of 2wo&lt;W.ltoreq.3D is satisfied, where D is the depth of said third semiconductor regions and wo is the width of a depletion layer spread to said first semiconductor region by a diffusion potential of the pn junction formed between said first semiconductor region and said third semiconductor region.

Semiconductor rectifying diode with pn geometry

When a microprocessor fetches an instruction to be processed by a coprocessor, it sends to the coprocessor a command corresponding to the instruction while informing the coprocessor that the bus cycle is in the mode of transfer of the instruction to the coprocessor. In transferring an operand from the memory to the coprocessor, the microprocessor asserts, in addition to a usual memory read signal, a signal (CYCYCL) indicative of validity of the coprocessor and instructs the coprocessor to fetch data to thereby complete the operand transfer from memory to coprocessor within one bus cycle. In transferring data from the coprocessor to the memory, the microprocessor asserts, in addition to a usual memory write signal, the CYCYCL signal and instructs the coprocessor to deliver the data to thereby complete the data transfer from memory to coprocessor within one bus cycle. Thus, the signal transfer between memory and coprocessor can be completed within one bus cycle without resort to the provision of duplicate hardware in the coprocessor.

Data processing system with coprocessor

A function arithmetic unit which performs elementary operations at high speeds and which enables required memory capacity to be reduced. The function arithmetic unit includes a constant memory which stores a constant that corresponds to the number of successive iterative operations; a controller which causes addition or subtraction in the successive iterative operations; and arithmetic units which receive, as initial values, an argument of an elementary function value to be found and two constants determined depending upon the elementary functions to be found, and which subject these initial values to n iterative operations to produce elementary function values. A further arithmetic unit subjects the elementary function values to multiplication, addition, subtraction, or division, or a combination thereof, thereby to produce the thus obtained value.

Elementary function arithmetic unit

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Hitachiota, Japan

Takao Yaginuma