Abstract: In order to realize a small quartz oscillator having high frequency stability and capable of measuring DLD characteristics, in a piezo-oscillator comprising an oscillator circuit including a piezo-vibrator and an amplifier circuit, and a constant-voltage circuit, in which a power source and the oscillator circuit are connected through the constant-voltage circuit to supply a constant voltage to the oscillator circuit, depending on the said power source voltage, a function of the constant-voltage circuit is invalidated. With this structure, even after the piezo-vibrator and other electron circuits are integrally assembled, it is possible to adjust the drive level of the quartz vibrator and to measure the DLD characteristics by changing the power source voltage.

Abstract: In a filter in which first-order to third-order. double mode SAW filters each including three IDT electrodes having an electrode finger pitch L1 are cascaded, to flatten the passband of the filter and reduce the VSWR to 2 or lower, a pitch of electrode fingers of the IDT electrode in the center of one of the double mode SAW filters is set as L2, the electrode fingers of the IDT electrode are eliminated by the same number from both sides, and the eliminated electrode fingers are replaced by dummy electrodes having a pitch L2. L2 is set to be higher than L1.

Abstract: A piezoelectric resonator has a piezoelectric substrate on obverse and reverse surfaces of which electrodes are disposed. Comb-shaped electrodes consisting of electrode fingers and spaces are disposed around the electrode situated at least on one surface of the piezoelectric substrate and at prescribed space intervals between this electrode and each of those comb-shaped electrodes. This arrangement enables obtaining means for suppressing the occurrence of spurious waves due to an inharmonic mode in the 200-MHz band high-frequency resonator or two-pole monolithic filter.

Abstract: There is provided a root finding circuit of a quadratic polynomial over a finite field, capable of operating at high speed and making the circuit scale in implementation small. The root finding circuit includes m−3 cascade-connected exclusive OR gates X(1, 0) to X(1, m−4) each supplied with a corresponding bit of an arbitrary element “a=(a0, a1, . . . , am−1)” over a finite field GF(2m) at a first input thereof and each supplied with output of an exclusive OR gate of an immediately preceding stage at a second input, a second input of only X(1, 0) being supplied with am−1 instead of the output of an exclusive OR gate of an immediately preceding stage, and m/2−1 exclusive OR gates X(2, 0) to x(2, m/2−2) respectively supplied with am−1 and outputs of X(1, 1), X(1, 3), . . . , X(1, m−5) at first inputs and each supplied with a0 at a second input thereof.

Abstract: The piezoelectric oscillator is a Colpitts circuit including a piezoelectric vibrator and a load capacitance in the oscillating loop and a limiter circuit. The excitation signal from the piezoelectic vibrator is supplied to the limiter circuit, and the limiter circuit controls the inter-terminal impedance of the capacitor which is connected to the limiter based on variations in the excitation signal and thus clips the level of the excitation signal.

Abstract: When communications are performed between a transmitter 2 and a receiver 3 via a transmission path 4, the transmitter prepares a basic sequence consisting of two-phase or four-phase tips, and transmits an expanded transmission frame which is constructed by repeatedly arranging one or a plurality of the basic sequence so as to obtain a finite length periodic sequence with a comb-form spectrum and by adding the replica of one or a plurality of tips of a back portion and front portion of the finite length periodic sequence to the outside of the front portion and the outside of the back portion of the finite length periodic sequence; and the receiver demodulates the expanded transmission frame using a matched filter which is matched with the finite length periodic sequence which is the central part of the expanded transmission frame, that is not including the added tips. In other words, the present invention can simplify the construction of communication equipment by using two-phase signals or four-phase signals.

Abstract: In a monocrystal producing device using a pulling-down method, a raw material melt 5m is continuously supplied into a crucible 2 to grow a crystal 18 by supplying a powdery raw material 5p onto a premelt plate 3 inside an electric furnace 10 with a powdery raw material supplying device 20 and melting the powdery raw material 5p on the premelt plate 3 to generate the raw material melt 5m, and causing this raw material melt 5m to drop out inside the crucible 2. A dry air is introduced into the powdery raw material 5p inside the powdery raw material tank 6 to prevent moisture of the raw material powder 5p. A transferring tube 9 for transferring the raw material 5m is cooled to prevent the filling in the transferring tube 9 based on melting of the powdery raw material 5p. This makes it possible to produce a monocrystal having a stable chemical composition, a large diameter, and a long size at a low price.

Abstract: In a longitudinally coupled multi-mode surface acoustic wave filter, for the purpose of setting a stop band width of reflectors to a proper width according to a required filter, since a line occupation rate of the reflectors has been made smaller than a line occupation rate of an IDT electrode, and respective periods of the reflector and the IDT electrode are set properly such that the stop band width of the reflector and the band width of the longitudinally coupled multi-mode surface acoustic wave filter have been approximately equal to each other, means for broadening the band of the longitudinally coupled multi-mode SAW filter can be obtained for a broad-band RF filter of a portable telephone used in a new system.

Abstract: Disclosed is a piezoelectric resonator that has a piezoelectric plate that has formed thereon a pair of main electrodes and has formed thereon a second electrode surrounding the peripheral edge of the main electrode with a gap being provided between the second electrode and a peripheral edge of the main electrode. The material of the main electrode and the material of the second electrode are differentiated from each other. As the material of the second electrode there is used a material the density of that is lower than the material of the main electrode. With this construction, there is obtained means for suppressing the occurrence of spurious due to an inharmonic mode generating in the high frequency piezoelectric resonator.

Abstract: A surface acoustic wave transducer is provided having three electrode fingers disposed as one reference segment (&lgr;) on a piezoelectric substrate, each segment including an electrode finger 1 having a width W1, an electrode finger 2 having a width W2 with a gap of g1, and an electrode 3 having a width 3 with a gap g2. The electrode fingers 1 and 3 are set in-phase, and the electrode finger 2 is set in an opposite phase for driving. Further, W1 is set equal to W3, and g1 is set equal to g2. Thus, it is possible to provide a SAW transducer that has improved a shape factor at a high-pass side near a pass band of a primary-third order longitudinally coupled double mode SAW filter.

Abstract: The present invention involves an inexpensive piezoelectric oscillator that offers excellent aging characteristics. The piezoelectric oscillator comprises a piezoelectric vibrator, a load capacitor, and a limiter circuit, wherein an excitation signal from the piezoelectric vibrator is supplied to the limiter circuit, and in which the limiter circuit controls the inter-terminal impedance based on variations in the excitation signal. The present invention thus provides an inexpensive crystal oscillator with excellent aging characteristics.

Abstract: To obtain means for suppressing a jump phenomenon to a B mode in a Colpitts oscillator using an SC-cut crystal unit. In a Colpitts oscillator including a piezoelectric resonator and an amplifier circuit, a series resonance circuit and a parallel resonance circuit consisting of an inductance and a capacitance are inserted into an oscillation loop, and the frequency of the series resonance circuit is set in the vicinity of the oscillation frequency of the oscillator, and the frequency of the parallel resonance circuit is set in the vicinity of an unwanted oscillation frequency of the oscillator, thereby to suppress the unwanted oscillation.

Abstract: A piezoelectric oscillator which is excellent in noise characteristic and aging characteristic is implemented by a piezoelectric oscillator comprising: a Colpitts oscillator including a piezoelectric resonator and an oscillation transistor; amplification means for amplifying an output of the Colpitts oscillator; and rectification means for rectifying an output of the amplification means, an output of the rectification means being fed back to base of the oscillation transistor to keep an oscillation output level constant, in which a base bias is set so as to provide the oscillation transistor with an operation point located in the vicinity of a saturation region, and in which a feedback current from the rectification means is supplied to the base of the oscillation resistor so as to make the operation point approach to the saturation region when the saturation output level has become high and so as to make the operation point go away from the saturation region when the oscillation output level has become low.

Abstract: There are disposed on a printed substrate a crystal resonator as a piezoelectric resonator, an oscillation circuit, a plurality of surface mount heaters and a temperature controlling circuit for controlling a heating temperature of the heaters. A case of the piezoelectric resonator and a lead terminal of the piezoelectric resonator are heated respectively at the same time by individually separate heaters for the purpose of heating the piezoelectric resonator, the oscillation circuit and the temperature controlling circuit at the same time. Accordingly, it is possible to provide a piezo-oscillator excellent in low power consumption and compactness.

Abstract: A method and a circuit for multiplication on a finite field which operate fast and involve a small circuit scale. There is provided a multiplication circuit on a finite field for multiplication of two arbitrary elements a=(a.sub.0, a.sub.1, . . . , a.sub.m-1) and b=(b.sub.0, b.sub.1, . . . , b.sub.m-1) of a Galois field GF(2.sup.m) utilizing a polynomial .function.=x.sup.m +x.sup.m-1 + . . . +x+1 as a polynomial to derive the GF(2.sup.

Abstract: In an AT-cut quartz resonator having excitation electrodes formed on two principal surfaces of an AT-cut quartz substrate, the two electrodes are displaced a predetermined amount apart in a direction orthogonal to the X-axis direction so that a frequency deviation in a temperature range of from -10.degree. C. to 50.degree. C. is less than .+-.2.5 ppm. Further, in an AT-cut quartz resonator in which vertically opposed electrodes on both principal surfaces of a quartz substrate are slightly displaced apart in opposite directions along the Z' axis of quartz crystal, a balancing load is formed on a piezoelectric substrate on the side opposite to the direction of displacement of the electrodes.

Abstract: In a piezoelectric vibrator which has excitation electrodes respectively disposed on the top surface and undersurface of a piezoelectric substrate, at least one of the excitation electrodes being an inverted-mesa electrode that has a recess formed in the opposite side of the electrode from the side which contacts the piezoelectric substrate. Thus, an AT-cut quartz resonator in which the capacitance ratio .gamma. is reduced to a value below the limit value can be provided as a result of use of the inverted-mesa electrodes as excitation electrodes.

Abstract: A unit for suppressing harmonic vibration of a lower order which does not have desired frequency in an overtone resonator consisting main electrodes and sub electrodes. Harmonic vibration of a lower order suppressing piezoelectric vibrator comprises main electrodes arranged on a piezoelectric substrate and sub electrodes arranged in the vicinity of the main electrodes with gaps provided therebetween. If the electric equivalent circuit of the resonator is expressed by a coupling circuit which connects in series a circuit, which connects in parallel a series resonance circuit by the sub electrodes and coupling capacity indicating that the main electrodes are coupled with the sub electrodes, to a series resonance circuit by the main electrodes, then their loop frequencies substantially coincide with each other.

Abstract: An optical element has a diffraction grating pattern formed on a double refracting thin plate around a centrally-disposed region of a desired shape. The diffraction grating pattern is composed of equally spaced ion exchange regions each having a predetermined width, a predetermined length and a predetermined thickness in the direction of optical axis of incident light thereon and dielectric films each formed all over the top surface of one of the ion exchange region. The thicknesses of each ion exchange region and each dielectric film are selected such that the diffraction grating pattern allows the passage therethrough of an ordinary ray and inhibit the passage therethrough of a zero-order diffracted wave of an extraordinary ray. The optical element permits implementation of an easy-to-handle optical pickup that facilitates miniaturization of the playback system.