Integrated direct drive inductor means enabled headphone amplifier
AssigneeMaxim Integrated Products, Inc.
InventorTony Doy
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Abstract
A headphone driver amplifier operative from a single DC voltage supply, coupled directly to the headphone speakers without the need for DC coupling capacitors used for preventing DC reaching the headphones. An onboard power supply generates a negative voltage rail which powers the output amplifiers, allowing driver amplifier operation from both positive and negative rails. Since the amplifiers can be biased at ground potential (O volts), no significant DC voltage exists across the speaker load and the need for DC coupling capacitors is eliminated.
Claims13
A circuit enabling a headphone driver amplifier to operate from a single voltage supply comprising:
- an amplifier having an output coupled to a headphone, said amplifier having a first and a second power supply lead, said first power supply lead connected to a power supply voltage;
- and
- a inductor based DC voltage to voltage converter having an output, said DC voltage to voltage converter having a power source lead connected to the supply voltage, the output of said DC voltage to voltage converter connected to the second power supply lead, and said DC voltage to voltage converter generating an output voltage at the output that is substantially equal in magnitude to some negative quanta of the power supply voltage.
An amplifier circuitry for directly driving stereo headphones, said amplifier circuitry being driven by a single supply voltage VDD, said amplifier circuitry comprising:
- a first and a second amplifier, the first amplifier having an output directly coupled to a first headphone and the second amplifier having an output directly coupled to a second headphone, each of the first and second amplifier having a VDD power supply lead connected to a positive voltage supply VDD;
- and
- an inductor based voltage to voltage converter output connected to a −VDD supply voltage of the first and second amplifier, wherein said inductor based voltage to voltage converter output provides a voltage substantially equal in magnitude to the negative value of the VDD supply, said inductor based voltage to voltage converter further having a power supply lead connected to the VDD supply voltage.
An portable amplifier system operative with a single voltage supply VDD, for directly driving a headphone comprising:
- signal amplifying means for driving a headphone, said amplifying means output directly coupling the headphone, said amplifying means biased to ground voltage;
- and
- negative voltage generator means for inverting an input voltage supply VDD to an output voltage supply −VDD of equal magnitude but opposite sign, said voltage supply generator means output coupled to the negative voltage lead −VDD of said amplifying means, said negative voltage generator means being an inductor based type of generator means.
A headphone system operative with a single positive supply voltage comprising:
- at least one headphone,
- signal amplifying means driving the headphone, wherein said amplifying means is directly coupled to said headphone and biases the headphone at substantially zero volts;
- and
- a negative voltage generator means providing a negative voltage substantially equal to but negative in magnitude to the positive voltage supply, said negative voltage generator means being an inductor based type of generator means.
A circuit enabling a driver amplifier to operate from a single voltage supply comprising:
- an amplifier having an output driving a load, said amplifier having a first and a second power supply lead, said first power supply lead connected to a supply voltage;
- and
- an inductor based DC voltage to voltage converter circuitry having an output, said inductor based DC voltage to voltage converter circuitry having a power source lead connected to the supply voltage, the output of said inductor based DC voltage to voltage converter circuitry connected to the second power supply lead and said output being substantially equal in magnitude to some negative quanta of the power supply voltage.
A method of directly driving a load in a portable device operative off of a single voltage supply VDD comprising:
- driving a headphone using a signal amplifying means having an output, wherein said output directly coupled to the headphone, said amplifying means biased to ground voltage;
- and
- inverting an input voltage using an inductor based negative voltage generator means for inverting a voltage supply VDD to an output voltage, said output voltage being substantially equal to some negative quanta of the voltage supply VDD, said negative voltage supply generator means output coupled to the negative voltage lead −VDD of said amplifying means.
A headphone amplifier circuit comprising:
- a first amplifier having a first power supply lead and a second power supply lead, said first power supply lead coupled to a power supply voltage,
- a second amplifier having a third power supply lead and a fourth power supply lead, said third power supply lead coupled to said power supply voltage,
- a switching unit coupled to said second power supply lead and said fourth power supply lead,
- an inductor having a fifth lead and a sixth lead, said fifth lead and said sixth lead coupled to said switching unit, and
- a capacitor having a seventh lead and an eighth lead, said seventh lead coupled to said sixth lead and said eighth lead coupled to ground;
- wherein said inductor and said capacitor operate to convert a positive power supply voltage to a substantially equal but negative power supply voltage.
Dependencies are inferred from the claim text.