Nippon Gakki Seizo Kabushiki Kaisha

Yamaha Corporation

Toshiyuki Takahashi

Masahiko Koike

Takeshi Adachi

Takayuki Kohdaka

Katsuhiko Ishida

Takashi Ogata

Shigeru Suga

Haruyuki Suzuki

Touhachi Makino

A semiconductor integrated circuit including a MOSFET having a polycide gate structure, a resistor and a capacitor is monolithically manufactured. Polycrystalline silicon film, a dielectric film, and another polycrystalline silicon film are consecutively deposited. After processes of patterning and etching the dielectric film, the remaining dielectric films are used as an etching protection mask for the resistor and a capacitor. A refractory metal silicide for a polycide gate is uniformly deposited over the remaining another polycrystalline silicon films and dielectric films. The refractory metal silicide and polycrystalline silicon are consecutively etched through a patterned resist mask and the remaining dielectric films to simultaneously form the polycide gate, resistor and capacitor. Thus, a capacitor having small change in capacitance versus applied voltage is manufactured in a MOS IC device having a polycide gate.

Method of forming a semiconductor device having a capacitor and a

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

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

An electronic musical instrument comprises a keyboard circuit providing a pitch determining voltage signal whose magnitude corresponds to the note of a key depressed, a rectangular wave generation circuit generating a rectangular wave voltage signal, and a voltage controlled oscillator connected to receive the pitch determining voltage signal and the rectangular wave voltage signal to produce alternately first and second tone signals for trill performance. The tone pitch of the first tone signal depends on the magnitude of pitch determining voltage signal and the tone pitch of the second tone signal depends on the magnitudes of pitch determining voltage signal and rectangular wave voltage signal. The musical intervals between tone pitches of the first and second tone signals depends on the magnitude of rectangular wave voltage signal.

Electronic musical instrument with automatic trill performance function

A pitch bend apparatus for electronic musical instrument having a voltage-controlled oscillator that works as a tone generator is provided with a first variable resistor for operating the pitch bend as well as a second variable resistor for setting a varying width of pitch bend or a maximum amount of pitch deviation. The varying width of the pitch bend is controlled by connecting the first and second variable resistors into an amplifier circuit to control the gain thereof, or by controlling the voltage applied to the first variable resistor by means of the second variable resistor.

Pitch bend apparatus for electronic musical instrument

An electronic musical instrument comprises first and second voltage-controlled frequency-variable oscillators responsive to application of a pitch determining voltage signal from a keyboard circuit to produce first and second audible frequency signals, respectively. The second audible frequency signal is coupled to the first voltage-controlled oscillator to produce a frequency-modulated tone signal to be sounded in which the first audible frequency signal is frequency-modulated with the second audible frequency signal. The content of harmonic components in a musical tone can be increased by sideband components resulting from frequency modulation. The second audible frequency signal may be amplitude-controlled to be proportional, in amplitude, to the magnitude of pitch determining voltage signal, amplitude-modulated with a time-varying control waveform, and/or waveform-modified to provide desirable modulation effects. The mixture of the pitch determining voltage signal and the second audible frequency signal may be coupled to the first voltage-controlled oscillator through an absolute value circuit. The second audible frequency signal may be also coupled to a sound system together with the frequency-modulated tone signal.

Growing community of inventors

Hamamatsu, Japan

Toshiyuki Takahashi