Rohm Co., Ltd.

Kei Nishioka

Masanori Fujisawa

Chung Chien San

Katsumi Kusaba

A packaged semiconductor device has an integrated chip and a non-integrated chip. The integrated chip has an integrated circuit and first bump pads formed with a narrow pitch. The non-integrated chip has second bump pads formed so as to face the first bump pads, lead pads formed with a wide pitch (so as to permit connection thereto of wires), and wiring conductors electrically connecting these pads together. The two chips are connected together by way of bumps and are then sealed in resin. With this structure, it is possible to realize a low-cost packaged semiconductor device that can easily be mounted on a mother board.

Packaged semiconductor device

A surround-sound circuit has a delay time memory () for storing a digital audio input signal IN, and outputs the stored input signal as a surround-sound signal a predetermined time later. The input signal is compressed by a compressor () in the form of ADPCM encoder before it is stored in the memory (), and the compressed signal retrieved from the memory is expanded by an expander () in the form of ADPCM decoder before it is added to the input signal. The invention may reduce appreciably the amount of data to be stored in the memory, and hence the storage capacity of the RAM, without directly loping the audio input signal IN and hence avoiding appreciable deterioration of the signal IN.

Method and apparatus for generating surround-sound data

A semiconductor integrated circuit device (IC) incorporates an array Dch of measurement elements D -Dm in the form of buffers for example connected in series. These elements represent standard internal elements of the IC The array Dch is supplied with a signal in synchronism with a fast clock signal CLK of the IC The propagation speed of the signal is given in terms of the number of the measurement elements through which the propagation signal has passed in one clock interval. This can be done by simply supplying the IC with a test signal GO and a reset signal RES as the instruction signals from an external tester. A tester slower in the operating frequency than the IC can be used to measure the propagation speed of the IC

Semiconductor integrated circuit device

There is substantially provided a muting control circuit in which there is no difference in muting time between the muting utilizing capacitor charging and that utilizing capacitor discharging. A constant current source is in parallel with an external capacitor. The constant current source operates so as to decrease a charging current in the course of charging the external capacitor 20, whereas it operates so as to increase a discharging current in the course of discharging. Therefore, no substantial difference in muting time occurs.

Muting control circuit

A power amplifier circuit for an audio signal is provided with a switching control circuit and a switching circuit between an amplifier and a power source line or ground line and a smoothing circuit which smoothes current from the switching circuit and supplies the current to the amplifier, and the smoothing circuit is provided with a change-over switching circuit which operates to return a commutation current generated during switching OFF time to the smoothing circuit.

Power amplifier circuit for audio signal and audio device using the same

The present invention includes a first amplifier, a second amplifier, a switching circuit for switching power from a power source line at a frequency exceeding an audible frequency and feeding the first or second amplifier, a control circuit for controlling a switching period of the switching circuit such that the feeding power is changed correspondingly to a level of the audio signal correspondingly to a first difference in voltage between one of the audio signal and the audio signal amplified by the amplifier and the power or a second difference in voltage between one of the audio signal and the audio signal amplified by the second amplifier and the feeding power, a smoothing circuit for smoothing a power fed by said switching circuit and a capacitor adapted to be charged by a portion of current flowing from said smoothing circuit when the switching circuit is in OFF state and generating discharge current to be added to the output of one of the first and second output stage amplifiers when the switching circuit is in ON state, a loud speaker being driven by outputs of the first and second amplifiers.

The present invention includes a first push-pull amplifier for amplifying an audio signal, a second push-pull amplifier for inverting and amplifying the audio signal, a switching circuit for switching power from a power source line at a frequency exceeding an audible frequency and feeding the first or second amplifier, a control circuit for controlling a switching period of the switching circuit such that the feeding power is changed correspondingly to a level of the audio signal correspondingly to a first difference in voltage between one of the audio signal and the audio signal amplified by the amplifier and the power or a second difference in voltage between one of the audio signal and the audio signal amplified by the second amplifier and the feeding power and a capacitor provided between the outputs of the first and second amplifiers, a loud speaker being driven by outputs of the first and second amplifiers.

The present invention includes an amplifier for amplifying an audio signal, a switching circuit for switching power from a power source line at a frequency exceeding an audible frequency and feeding the amplifier and a control circuit for controlling a switching period of the switching circuit such that the power feeding the amplifier correspondingly to a difference in voltage between the feeding power and one of the voltage of the audio signal and the voltage of the audio signal amplified by the amplifier is changed correspondingly to a level of the audio signal.

The present invention includes a first push-pull amplifier for amplifying an audio signal, a second push-pull amplifier for inverting and amplifying the audio signal, a switching circuit for switching power from a power source line at a frequency exceeding an audible frequency and feeding the first or second amplifier and a control circuit for controlling a switching period of the switching circuit such that the feeding power is changed correspondingly to a level of the audio signal correspondingly to a first difference in voltage between one of the audio signal and the audio signal amplified by the amplifier and the power or a second difference in voltage between one of the audio signal and the audio signal amplified by the second amplifier and the feeding power, a loud speaker being driven by outputs of the first and second amplifiers.

In an amplifying circuit of current subtraction type, a first output of a differential amplifier is coupled through a first transistor to an output electrode of an output-side transistor of a current mirror circuit and a second output of the differential amplifier is coupled through a second transistor to an input electrode and an output electrode of an input-side transistor of the current mirror circuit so that an output current based on a difference between the first output and the second output flows out from a connection of the first transistor and the output-side transistor of the current mirror circuit. A first circuit device for phase compensation is inserted between bases of input-side and output-side transistors of one of the first and second transistors, and a second circuit device for compensating a direct current offset generated by the first circuit device is .inserted between bases of input-side and output-side transistors of the other of the first and second transistors.

Amplifying circuit

A recording/reproducing circuit according to the present invention comprises a recording amplifier for outputting a recording signal, a differential amplifier including a pair of transistors, a base of one of the transistors being a (+) side input, a base of the other transistor being a (-) side input, emitters of the transistors being connected commonly to a current source, the (+) side input being supplied with the recording signal, an output signal being fedback to the (-) side input, the output signal being sent to a recording head and means for cutting a current of the current source to thereby stop an outputting of the recording signal from the differential amplifier circuit.

Recording/reproducing circuit and recording/reproducing apparatus having

An audio amplifier circuit according to the present invention features an arrangement of a power line with a smoothing capacitor inserted as a power filter and a power line without such a smoothing capacitor. The audio amplifier circuit in which an input stage amplifier of a main amplifier is supplied with power via the former power line has a muting circuit for rapidly charging a negative feedback capacitor for generating negative feedback voltage to be fed back from the following stage of the main amplifier to the input stage amplifier up to a voltage level at which a pop sound is inhibited when the power is supplied and for rapidly discharging the negative feedback capacitor up to a reference operating voltage level when the voltage of the former power line with the smoothing capacitor exceeds a predetermined level, the voltage of the former power line being monitored after the power is supplied from a power supply. In this way, the negative feedback capacitor connected to the input stage amplifier of the main amplifier is caused to perform a muting operation by rapidly charging the capacitor up to a level higher than a pop sound level. A point of time the muting operation terminates is determined by a point of time the negative feedback capacitor is caused to start to discharge itself by rapidly discharging the charge of the negative feedback capacitor.

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Kyoto, Japan

Kei Nishioka