US 5,892,398 AGranted

Amplifier having ultra-low distortion

AssigneeBHC Consulting Pty., Ltd.

InventorBruce Halcro Candy

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Abstract

This invention is for an improvement in amplifiers resulting in ultra low distortion. It relates to amplifiers consisting of three stages, an input stage which amplifies an input signal and provides a first signal to an intermediate stage which amplifies the first signal and provides a second signal to an output stage which amplifies that second signal and provides an amplifier output signal, the amplifier further including a power supply to provide power to the three stages and wherein the low distortion is achieved by the output stage including output transistors connected to provide the amplifier output signal and further including an error correction means that comprises an input buffer means, an adding means, a subtracting means and a voltage follower buffer means wherein the adding means sums the second signal with a difference signal to produce an output sum signal the said output sum signal fed to the voltage follower buffer means which then provides a buffered output sum signal, which is then fed to the inputs of the output transistors and to the subtracting means, the amplifier output signal is also fed to the subtracting means which is adapted to subtract the amplifier output signal from the buffered output sum signal to produce a difference signal and a first bootstrap power supply to provide power to the error correction means, the bootstrap power supply closely tracking the output signal by means of bootstrapping.

Claims20

Dependent claims

An electronic amplifier apparatus comprising an input stage, to which an amplifier input signal is applied and which is adapted to amplify the amplifier input signal and to provide a first signal to an intermediate stage adapted to amplify the said first signal and further adapted to provide a second signal to an output stage adapted to amplify the said second signal and further adapted to provide an amplifier output signal to an amplifier output, and a power supply means adapted to provide power to the input stages the intermediate stage and the output stage, wherein:

the output stage includes output transistors connected so as to provide the amplifier output signal and further includes an error correction means comprising an input buffer means, an adding means, a subtracting means and a voltage follower buffer means wherein,
the input buffer means adapted to receive the second signal and connected to the adding means,
the said adding means is adapted to sum the second signal with a difference signal to produce an output sum signal,
the said voltage follower buffer means is adapted to provide a buffered output sum signal when fed the output sum signal,
the buffered output sum signal is fed to inputs of the output transistors and to the subtracting means,
the amplifier output signal is fed to the subtracting means which is adapted to subtract the amplifier output signal from the buffered output sum signal to produce the difference signal, and
a first bootstrapped power supply is adapted to provide power to the error correction means, the first bootstrapped power supply further adapted to closely track the output signal by means of bootstrapping.

4 more elements

A method of electronic amplification including applying an amplifier input signal to an amplifier input stage to amplify the amplifier input signal and provide a first signal, amplifying said first signal by an intermediate stage and providing a second signal, amplifying said second signal by an output stage that provides an amplifier output signal to an amplifier output, the stages provided power by a power supply means;

the output stage containing output transistors which provide the amplifier output signal and also containing an error correction means consisting of an input buffer means, an adding means, a subtracting means and a voltage follower buffer means,
the input buffer means adapted to receive the second signal and connected to the adding means;
and further including the steps of:
summing in the adding means the buffered second signal with a difference signal to produce an output sum signal,
feeding the voltage follower buffer means with the output sum signal to provide a buffered output sum signal,
feeding the buffered output sum signal to inputs of the output transistors and to the subtracting means,
feeding the amplifier output signal to the subtracting means which subtracts the amplifier output signal from the buffered output sum signal to produce the difference signal, and
supplying power to the error correction means by a first bootstrapped power supply which closely tracks the output signal by means of bootstrapping.

5 more elements

Dependencies are inferred from the claim text.