Light receiving amplifier circuit and optical pickup device having the same

A light receiving amplifier circuit comprising:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each further including a bias-use constant current source for supplying a bias current to the base, and
• the band limiting capacitor being connected between the base and the output node of the grounded-emitter amplifier circuit.

A light receiving amplifier circuit comprising:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each further including a bias-use constant current source for supplying a bias current to the base, and
• the band limiting capacitor being connected between the base and a grounded point where the emitter is grounded.

A light receiving amplifier circuit comprising:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each further including a bias-use constant current source for supplying a bias current to the base, and
• the band limiting capacitor being connected in parallel to the feedback resistors.

An optical pickup device comprising a light receiving amplifier circuit as a light receiving amplifier used for optical pickup of an optical disk, the light receiving amplifier circuit including:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the band limiting capacitor being connected between the output node of the grounded-emitter amplifier circuit and a grounded point where the emitter is grounded.

An optical pickup device comprising a light receiving amplifier circuit as a light receiving amplifier used for optical pickup of an optical disk, the light receiving amplifier circuit including:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each further including a bias-use constant current source for supplying a bias current to the base, and
• the band limiting capacitor being connected between the base and the output node of the grounded-emitter amplifier circuit.

An optical pickup device comprising a light receiving amplifier circuit as a light receiving amplifier used for optical pickup of an optical disk, the light receiving amplifier circuit including:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each further including a bias-use constant current source for supplying a bias current to the base, and
• the band limiting capacitor being connected between the base and a grounded point where the emitter is grounded.

An optical pickup device comprising a light receiving amplifier circuit as a light receiving amplifier used for optical pickup of an optical disk, the light receiving amplifier circuit including:

• a light receiving element which converts received light into a current and outputs the current thus converted;
• a current-to-voltage conversion circuit which converts the output current of the light receiving element into a voltage;
• a reference voltage supplying amplifier having an identical structure with the current-to-voltage conversion circuit except that the light receiving element is not connected and a band limiting capacitor is provided;
• and
• a differential amplifier circuit which amplifies a difference between the output voltage of the current-to-voltage conversion circuit and a reference voltage that is an output voltage of the reference voltage supplying amplifier,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each including:
• a grounded-emitter amplifier circuit employing a grounded-emitter transistor, the grounded-emitter transistor having a base serving as an input terminal, and a terminal serving as an output terminal for obtaining an output voltage which varies depending on an output from an output node of the grounded-emitter amplifier circuit;
• and
• a plurality of feedback resistors being provided in parallel on feedback paths from the output terminal to the base so as to be selectively used,
• the current-to-voltage conversion circuit and the reference voltage supplying amplifier each further including a bias-use constant current source for supplying a bias current to the base, and
• the band limiting capacitor being connected in parallel to the feedback resistors.