Yamaha Corporation

Nippon Gakki Seizo Kabushiki Kaisha

Takashi Ogata

Takayuki Kohdaka

Toshiyuki Takahashi

Katsuhiko Ishida

Masao Kosugi

A digital-to-analog converter converts digital data in the floating-point representation into an analog signal. The mantissa part of the digital data is first converted into a first analog signal by an R-2R resistor ladder network. The first analog signal thus obtained is directly supplied to another r-2r resistor ladder network to produce second analog signals whose values are 2.sup.-N (N=0, 1, 2, . . . ) magnifications of the first analog signal. And, one of the second analog signals is selectively outputted in accordance with the exponent part of the digital data. A data converter is also provided for converting digital data in the form of a fix-point number into floating point data.

Floating point digital to analog converter with bias to establish range

For preventing a semiconductor substrate from a heat attack, a method of rapid annealing using a lamp unit for a heat radiation comprises the step of preparing a semiconductor substrate having a multiple-layer structure and a vessel having an annealing chamber where the lamp unit is placed, the vessel is associated with an inert gas supplying system operative to supply a high-pressure inert gas to the annealing chamber, and the above step is followed by the steps of placing the semiconductor substrate in the annealing chamber, supplying the high-pressure inert gas to the annealing chamber so as to create a high-pressure inert ambient within a predetermined range and activating the lamp unit for the heat radiation so as to heat up the semiconductor substrate, so that the heat radiation is decreased in intensity by virtue of the high-pressure inert ambient.

Rapid annealing under high pressure for use in fabrication of

A digital-to-analog converter (DAC) converts digital input data into an analog output signal with less harmonic distortion over an entire signal-level range. An exponent value detector detects from the digital input data the number of bits by which the digital input data is to be shifted to form a mantissa part thereof. A digital shifter shifts the digital input data in accordance with the output of the exponent value detector, and outputs the mantissa part which is then supplied to a mantissa-part DAC. The mantissa-part DAC comprises an R-2R resistor ladder network and outputs the result of DA conversion of the mantissa part to an exponent-part DAC. The exponent DAC shifts the output of the mantissa-part DAC by an amount determined by the output of the exponent value detector, and outputs the shifted signal as the analog output signal of this DAC. A control circuit is provided between the digital shifter and the mantissa-part DAC, which prevents, in accordance with the output of the exponent value detector, the least significant bits of the mantissa-part DAC from operatively functioning to thereby decrease the number of operable bits thereof when the magnitude of the digital input data is small.

Digital-to-analog converter

On a common semiconductor wafer constituted by a PN-lamination are formed a number of semiconductor device units. Recessed grooves are formed into this wafer by an etching technique at such sites as one corresponding to the boundaries of the respective adjacent semiconductor device units. To protect the PN-junctions of the wafer exposed on the etched grooves, these surfaces are coated with a thermo-setting resin. Thereafter, the semiconductor wafer is severed apart at the respective recessed grooves into respective individual chips of semiconductor devices.

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Hamamatsu, Japan

Takashi Ogata