Matsushita Electric Industrial Co., Ltd.

Masaharu Ikeda

Masayoshi Esashi

Takuya Ishii

Hiroki Akashi

Ryoji Abe

A power amplifying apparatus which is of a switching type and capable of efficiently amplifying a power of an input AC signal such as an acoustic signal, includes a first switch circuit () and a second switch circuit () to which a power supply voltage Vc is applied, an inductor () and a load () which are connected between the switch circuits, and a control circuit () which receives an input AC signal Vi, sets a predetermined ratio of ON/OFF periods, and drives the switch circuits. The control circuit () includes an arithmetic circuit () which multiplies a modulation sensitivity (for example, an amplitude of a triangular wave voltage used for generation of a pulse signal for driving a switch circuit) by a ratio (Vc/Ec) of the power supply voltage Vc and a DC component Ec thereof. This configuration can compensate for distortion caused by a ripple variation of the power supply voltage due to regenerated power or the like, and enable a gain control by the power supply voltage.

Power amplifying apparatus

A condenser microphone apparatus which is used for a radio apparatus in order to reduce noises generated due to radiation of a high frequency signal of a transmitting unit. A series resistor is provided between a bypass capacitor provided between a drain and a source of an FET and a microphone signal output transmission line in order to prevent a high frequency voltage from being increased due to a resonance of the bypass capacitor and microphone signal output transmission line. Thus, the noises due to the radiation of the high frequency signal can be reduced.

Condenser microphone apparatus and its connecting apparatus

A pressure transducer designed to transform static pressure or dynamic pressure applied to a diaphragm into a corresponding electrical signal and a method of manufacturing the same are provided. The transducer includes a fixed electrode formed in an upper surface of a substrate and a moving electrode provided in the diaphragm disposed above the fixed electrode through a cavity. The substrate has formed in the bottom thereof at least one hole which is used in a manufacturing process for removing a sacrificial layer formed between the diaphragm and the upper surface of the substrate in dry etching to form the cavity.

Pressure transducer and manufacturing method thereof

A guard electrode is formed on a frontside surface of a semiconductor substrate and a fixed electrode is formed on the guard electrode via an insulating layer. A cavity is formed on the fixed electrode by a diaphragm and a moving electrode is formed between the layers of the diaphragm. A substrate through hole directing from a backside surface of the substrate and reaching the cavity is formed. An operational amplifier which drives the guard electrode so as to equalize an electric potential of the guard electrode with that of the fixed electrode is provided. A change in the capacitance between the fixed electrode and a moving electrode is converted into a voltage directly concerned with a displacement of the diaphragm.

Capacitive transducer having guard electrode and buffer amlifying means

A light emitting device is operative for outputting a light beam having an intensity which increases as a drive current through the light emitting device increases. A power source is operative for supplying a drive current to the light emitting device. A control device connected to the power source and a first end of the light emitting device is operative for controlling the drive current to the light emitting device in response to an input signal. The control device has an input terminal subjected to the input signal. A photosensitive device is optically coupled to the light emitting device. A current flowing through the photosensitive device increases as an intensity of a light beam applied to the photosensitive device increases. The photosensitive device is connected between the input terminal of the control device and a second end of the light emitting device.

Driver for light emitting device

A common-source type buffer amplifier circuit has a microphone capsule, a diode and an FET. An output end of the buffer amplifier circuit, or a drain of the FET is connected to an input end of the current mirror circuit. An output end of the current mirror circuit is connected to one end of a load resistor of which the other end is grounded. A voltage across the load resistor corresponds to an output of the amplifier and is supplied to the speaker amplifier.

Amplifier device for a condenser microphone

A voltage generating device is capable of generating a voltage which does not depend upon temperature even if a power source voltage is not higher than 1.25 V. The device comprises an output terminal thereof, current sources, resistors and a diode like connected transistor. A voltage on the output terminal is obtained by causing a current to flow through series-connected resistors. The current sources are band gap current sources. The current source is assumed as opened. A part of the diode like connected transistor is represented by an equivalent circuit including a voltage source and a resistor. The equivalent circuit and the resistors are represented by an equivalent circuit by using the Thevenin's theorem.

Voltage generating device

A comparator device is designed for comparing the signal levels of first and second input signals to provide respective resultant comparator outputs independently, which comparator device is featured in avoidance of occurrence of simultaneous low levels of the comparator signals at all possible conditions of the comparator outputs. The comparator device includes first and second comparator which independently output resultant comparator outputs having either a high (H) level or a low (L) level as results of comparison of the signal levels of the first and second input signals while taking one of the input signals as a reference, and have offset characteristics and hysteresis characteristics so that the comparator outputs, either H level or L level, can be fixedly determined when the first and second input signal levels are equal to each other. The first input signal is applied to one of the input terminal of the first comparator and the other input terminal of the second comparator with a different polarity, and the second input signal is applied to the other input terminal of the first comparator and one of the input terminal of the second comparator with a different polarity.

Comparator device for selecting received signals

A current source including a first transistor and a second transistor with their bases connected together, a resistor connected to the emitter of the first transistor, a third transistor with its base connected to the collector of the second transistor, and an amplifying unit. The amplifying unit has its input end connected to the collector of the third transistor and is further provided with a plurality of output portions with output resistors. The plurality of output portions of the amplifying unit are connected to the collectors of the first transistor, second transistor and third transistor, respectively. The base current of the third transistor is set to make the collector currents of the first transistor and second transistor substantially equal.

Current source having current mirror arrangement with plurality of

For realizing a correct measurement of a receiving condition even if the bandwidth of intermediate frequency amplification is narrow, the gain of a variable gain amplitude detector circuit is controlled by an output signal of a function generator circuit so as to cancel the bandwidth characteristic of an intermediate frequency amplifier circuit, to flatten the total bandwidth characteristic of a circuit for detecting an amplitude value of a received signal, thereby eliminating the influence of angle modulation related components in the received signal or desired wave.

Receiver using receiving condition signal for correcting influence of

A comparator device is designed for comparing the signal levels of first and second input signals to provide respective of resultant comparator outputs independently, which comparator device is featured in avoidance of occurrence of simultaneous low levels of the comparator signals at all possible conditions of the comparator outputs. The comparator device includes first and second comparator which independently output resultant comparator outputs either of H level and L level as results of comparison of the signal levels of the first and second input signals with taking one of the input signals as reference, and have offset characteristics and hysteresis characteristics so that the comparator outputs, either H level or L level can be fixedly determined when the first and second input signal levels are equal to each other. The first input signal is applied to one of the input terminal of the first comparator and the other input terminal of the second comparator with different polarity, and the second input signal is applied to the other input terminal of the first comparator and one of the input terminal of the second comparator with different polarity.

Comparator device having maximum (minimum) value determining and

An amplifier is operated with a low power source voltage and has a reference voltage of 1.25 V or less. The temperature characteristic of the amplifier is controllable. The amplifier comprises substantially similar circuits and constants on its left and right sides under a condition that a voltage source is not connected to an input terminal, except that a diode-connected transistor is provided. Paying attention to the left-side circuit, the circuit which has the diode-coupled transistor having a forward voltage and resistors 22 and 23, is expressed by an equivalent circuit by the (Ho)-Thevenin theorem.

Amplifier including current mirror circuit and current generator

An angle modulation detector which prevents a demodulated output from being influenced by fluctuations in the amplitudes of signals generated from angle-modulated signal sources such as a phase-modulated signal and a frequency-modulated signal, even if the amplitude of a driving voltage applied to a connection between the bases of a pair of transistors constituting a phase detecting device is made larger in order to enhance the demodulation sensitivity and reduce noise produced during demodulation. As an example of a resolution, the angle modulation detector comprises two coupling devices, two current dividing devices coupled to generate a phase detecting output, a current dividing device coupled to generate a re-mixed output, and a phase detecting device, wherein the outputs of the two coupling devices are connected to the two current driving devices driven by the same signal, so that the respective input and output terminals are at the same voltage level, whereby two outputs thereof are not influenced by fluctuations in amplitudes of angle-modulated signals supplied to the coupling devices.

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Yokohama, Japan

Masaharu Ikeda