US 2014/0368949 A1Published application

Class-ab amplifier, motor device, magnetic disk storage device, and electronic apparatus

AssigneeRohm Co., Ltd.

InventorHisashi SUGIE

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Abstract

A class-AB amplifier has upper side and lower side transistors, a linear driver, upper side and lower side idlers, upper side and lower side detection current generators, and an off driver. The upper side and lower side idlers bias upper side and lower side gate voltages by generating upper side and lower side bias currents so as to turn on the upper side and the lower side transistors at the same time in the crossover region between an input voltage and a reference voltage respectively. The upper side detection current generator and the lower side detection current generator generates upper side and lower side detection currents in accordance with upper side and lower side bias currents respectively. The off driver controls the lower side gate voltage so as to reduce a degree of conduction of the lower side transistor as the upper side detection current is larger, and controls the upper side gate voltage so as to reduce a degree of conduction of the upper side transistor as the lower side detection current is larger.

Claims15

Dependent claims

A class-AB amplifier comprising:

an upper side transistor which is connected between an application terminal of a first power supply voltage and an application terminal of an output voltage;
a lower side transistor which is connected between an application terminal of a second power supply voltage and the application terminal of the output voltage;
a linear driver which generates an upper side gate voltage and a lower side gate voltage varying continuously with reverse polarity in accordance with an input voltage and a reference voltage to output the upper side gate voltage and the lower side gate voltage to the upper side transistor and the lower side transistor;
an upper side idler which biases the upper side gate voltage by applying an upper side bias current between an application terminal of the upper side gate voltage and the application terminal of the output voltage so as to turn on the upper side transistor in a crossover region between the input voltage and the reference voltage;
a lower side idler which biases the lower side gate voltage by applying a lower side bias current between an application terminal of the lower side gate voltage and the application terminal of the second power supply voltage so as to turn on the lower side transistor in the crossover region;
an upper side detection current generator which generates an upper side detection current in accordance with the upper side bias current;
a lower side detection current generator which generates a lower side detection current in accordance with the lower side bias current;
and
an off driver which controls the lower side gate voltage so as to reduce a degree of conduction of the lower side transistor as the upper side detection current is larger, and controls the upper side gate voltage so as to reduce a degree of conduction of the upper side transistor as the lower side detection current is larger.

6 more elements

A motor drive device comprising:

a voice coil motor driver which drives a voice coil motor, wherein
the voice coil motor driver includes each of the class-AB amplifier as a pair of driver circuits for generating output currents to the voice coil motor, and wherein
the class-AB amplifier comprising:
an upper side transistor which is connected between an application terminal of a first power supply voltage and an application terminal of an output voltage;
a lower side transistor which is connected between an application terminal of a second power supply voltage and the application terminal of the output voltage;
a linear driver which generates an upper side gate voltage and a lower side gate voltage varying continuously with reverse polarity in accordance with an input voltage and a reference voltage to output the upper side gate voltage and the lower side gate voltage to the upper side transistor and the lower side transistor;
an upper side idler which biases the upper side gate voltage by applying an upper side bias current between an application terminal of the upper side gate voltage and the application terminal of the output voltage so as to turn on the upper side transistor in a crossover region between the input voltage and the reference voltage;
a lower side idler which biases the lower side gate voltage by applying a lower side bias current between an application terminal of the lower side gate voltage and the application terminal of the second power supply voltage so as to turn on the lower side transistor in the crossover region;
an upper side detection current generator which generates an upper side detection current in accordance with the upper side bias current;
a lower side detection current generator which generates a lower side detection current in accordance with the lower side bias current;
and
an off driver which controls the lower side gate voltage so as to reduce a degree of conduction of the lower side transistor as the upper side detection current is larger, and controls the upper side gate voltage so as to reduce a degree of conduction of the upper side transistor as the lower side detection current is larger.

9 more elements

A magnetic disk storage device comprising:

a platter;
a magnetic head which reads and writes data to and from the platter;
a swing arm which holds the magnetic head at a tip end thereof;
a spindle motor which rotates the platter;
a voice coil motor which moves the swing arm in an arc;
and
a motor drive device which drives the spindle motor and the voice coil motor, wherein
the motor drive device comprising:
a spindle motor driver which drives the spindle motor, and
a voice coil motor driver which drives the voice coil motor, wherein
the voice coil motor driver includes each of the class-AB amplifier as a pair of driver circuits for generating output currents to the voice coil motor, and wherein
the class-AB amplifier comprising:
an upper side transistor which is connected between an application terminal of a first power supply voltage and an application terminal of an output voltage;
a lower side transistor which is connected between an application terminal of a second power supply voltage and the application terminal of the output voltage;
a linear driver which generates an upper side gate voltage and a lower side gate voltage varying continuously with reverse polarity in accordance with an input voltage and a reference voltage to output the upper side gate voltage and the lower side gate voltage to the upper side transistor and the lower side transistor;
an upper side idler which biases the upper side gate voltage by applying an upper side bias current between an application terminal of the upper side gate voltage and the application terminal of the output voltage so as to turn on the upper side transistor in a crossover region between the input voltage and the reference voltage;
a lower side idler which biases the lower side gate voltage by applying a lower side bias current between an application terminal of the lower side gate voltage and the application terminal of the second power supply voltage so as to turn on the lower side transistor in the crossover region;
an upper side detection current generator which generates an upper side detection current in accordance with the upper side bias current;
a lower side detection current generator which generates a lower side detection current in accordance with the lower side bias current;
and
an off driver which controls the lower side gate voltage so as to reduce a degree of conduction of the lower side transistor as the upper side detection current is larger, and controls the upper side gate voltage so as to reduce a degree of conduction of the upper side transistor as the lower side detection current is larger.

18 more elements

An electronic appliance comprising:

the magnetic disk storage device, wherein
the magnetic disk storage device comprising:
a platter;
a magnetic head which reads and writes data to and from the platter;
a swing arm which holds the magnetic head at a tip end thereof;
a spindle motor which rotates the platter;
a voice coil motor which moves the swing arm in an arc;
and
a motor drive device which drives the spindle motor and the voice coil motor, wherein
the motor drive device comprising:
a spindle motor driver which drives the spindle motor, and
a voice coil motor driver which drives the voice coil motor, wherein
the voice coil motor driver includes each of the class-AB amplifier as a pair of driver circuits for generating output currents to the voice coil motor, and wherein
the class-AB amplifier comprising:
an upper side transistor which is connected between an application terminal of a first power supply voltage and an application terminal of an output voltage;
a lower side transistor which is connected between an application terminal of a second power supply voltage and the application terminal of the output voltage;
a linear driver which generates an upper side gate voltage and a lower side gate voltage varying continuously with reverse polarity in accordance with an input voltage and a reference voltage to output the upper side gate voltage and the lower side gate voltage to the upper side transistor and the lower side transistor;
an upper side idler which biases the upper side gate voltage by applying an upper side bias current between an application terminal of the upper side gate voltage and the application terminal of the output voltage so as to turn on the upper side transistor in a crossover region between the input voltage and the reference voltage;
a lower side idler which biases the lower side gate voltage by applying a lower side bias current between an application terminal of the lower side gate voltage and the application terminal of the second power supply voltage so as to turn on the lower side transistor in the crossover region;
an upper side detection current generator which generates an upper side detection current in accordance with the upper side bias current;
a lower side detection current generator which generates a lower side detection current in accordance with the lower side bias current;
and
an off driver which controls the lower side gate voltage so as to reduce a degree of conduction of the lower side transistor as the upper side detection current is larger, and controls the upper side gate voltage so as to reduce a degree of conduction of the upper side transistor as the lower side detection current is larger.

20 more elements

Dependencies are inferred from the claim text.