BTL amplifier capable of providing stability of offset compensation
AssigneesRenesas Technology Corp., Renesas Device Design Corp.
InventorKatsumi Miyazaki
Life of this patent
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Abstract
A BTL amplifier has a resistance element connected to an output reference voltage input terminal of an inverting amplifier. For offset compensation of the BTL amplifier, a variable current source controller controls an input switching circuit to cause application of compensation input voltages sent from an internal reference voltage source to a first input terminal and a second input terminal. The variable current source controller also controls a variable current source in response to an output signal from a comparator to minimize an output offset voltage, whereby a current flowing through the resistance element is adjusted to control the voltage at the output reference voltage input terminal.
Claims5
A BTL (balanced transformer-less) amplifier system, comprising:
- a BTL amplifier including a differential amplifier for amplifying a voltage difference between first and second input terminals to output a first output voltage, and an inverting amplifier for inverting said first output voltage to output a second output voltage;
- a compensation input voltage application circuit capable of applying compensation input voltages at the same level to said first and second input terminals;
- a comparator for making comparison between first and second compensation output voltages which are respectively said first and second output voltages as a result of application of said compensation input voltages to said first and second input terminals;
- and
- a reference voltage control circuit for offset compensation, said offset compensation being realized by controlling a voltage at an output reference voltage input terminal of said inverting amplifier in response to an output signal from said comparator to minimize a difference between said first and second compensation output voltages.
Dependencies are inferred from the claim text.