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US 2008/0186097 A1Published application
Audio power amplifier apparatus
AssigneeSecondo Porra'
InventorsGiovanni STOCHINO, Secondo Porra'
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AssigneeSecondo Porra'
InventorsGiovanni STOCHINO, Secondo Porra'
Estimating the term…
The invention concerns an audio power amplifier apparatus capable of providing at low manufacturing cost extremely low non-linear distortion, even lower than −120 dB, comprising a main power amplifying section (3) the output of which is series connected to a secondary of a coupling transformer T1, in turn connected to the apparatus output (IO4), the apparatus being characterised in that the amplifying section (3) provides an output signal Vma having a negative feed-back loop non-inverting gain, and in that it further comprises a cascade of one or more sections (5, 6), the inputs of which are connected to the output of the input section (1) and to the output of the amplifying section (3), and the output of which is constituted of a secondary winding of the transformer T1, the cascade being capable to very accurately extract the error signal Ve with respect to the amplified signal Vi from the signal at the output of the amplifying section and to provide to its output an exact, but anti-phase, copy thereof in a predetermined very wide frequency band, so as to carry out a feed-forward error correction function that, for the first time, is particularly effective in cancelling the error of the amplifying section (3) without interactions with the same and in a very wide frequency band, and in avoiding in a very stable and reliable way, any risk of stress and overload for the transformer T1.
An audio power amplifier apparatus, capable to receive as input an external audio signal and to provide an amplified signal Vo for a load connected to at least one apparatus output terminal (IO4), the apparatus comprising an input section, capable to receive as input said external audio signal and to output an audio signal Vi, a main power amplifying section having an input connected to the output of the input section, wherein the amplifying section provides an output signal Vma having non-inverting gain with respect to the input audio signal Vi, and in that it further comprises a cascade of one or more sections, having two inputs, which are one non-inverting and the other inverting, the former being connected to the output of the input section and the latter being connected to the output of the power amplifying section, and an output terminal coinciding with a corresponding terminal out of two terminals of a first secondary of a transformer T1, that is connected to said at least one apparatus output terminal, the load being connected to the output of the power amplifying section and in series to the first secondary of the transformer T1, so that the amplified signal Vo is equal to the difference between a signal Vmo obtained from the signal Vma at the output of the power amplifying section and a signal Vb present across the two terminals (Vb1, Vb2) of the first secondary of the transformer T1 (Vb=Vb1−Vb2), the cascade being capable to extract an error component Ve, with respect to the amplified signal Vi, from the signal Vma at the output of the amplifying section, and to stably provide substantially a copy of such error component, without interactions with the amplifying section, across the two terminals (Vb1, Vb2) of the first secondary of the transformer T1, the cascade having such a frequency response that the signal Vb present across the two terminals (Vb1, Vb2) of the first secondary of the transformer T1 has substantially the same behaviour of amplitude and phase as the error component Ve in a first predetermined frequency band.
Dependencies are inferred from the claim text.