Abstract: A very low distortion amplifier using one or more error correction loops based on a balanced error negative feedback scheme intrinsically and easily reiterable. Such loops are applied to a generic amplifier block A1 in order to reduce its error in a wide frequency band, without substantially interfering, in the correction process, with the main path of the useful signal Vi, to amplify, whereby the corrected amplifier preserves the same response, in time and frequency, the same dynamic behavior and the same stability margins in amplitude and phase, of the not corrected amplifier A1. This result is obtained by means of a balance and reference block A2, capable to decouple the error correction loop from the main path of the useful signal Vi, in a very wide frequency band.

Abstract: A very low distortion amplifier using one or more error correction loops based on a balanced error negative feedback scheme intrinsically and easily reiterable. Such loops are applied to a generic amplifier block A1 in order to reduce its error in a wide frequency band, without substantially interfering, in the correction process, with the main path of the useful signal Vi to amplify, whereby the corrected amplifier preserves the same response, in time and frequency, the same dynamic behavior and the same stability margins in amplitude and phase, of the not corrected amplifier A1. This result is obtained by means of a balance and reference block A2, capable to decouple the error correction loop from the main path of the useful signal Vi in a very wide frequency band.

Abstract: 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 the output of which is series connected to a secondary of a coupling transformer T1, in turn connected to the apparatus output, the apparatus being characterized in that the amplifying section 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, the inputs of which are connected to the output of the input section and to the output of the amplifying section, 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 to provide to its output an exact, but anti-phase, copy thereof in a predetermined very wide fr

Abstract: 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

Abstract: In an amplifier with improved, high precision, high speed and low power consumption architecture, comprising an input stage (1), an intermediate stage (2) and an output stage (3), the intermediate stage (2) is provided by combining two complementary class AB operating halves (2a, 2b) which are driven by a complementary input stage, which is, in turn, class AB operating, one of said halves having a low limited current gain (GU), conveniently but not necessarily controlled, and the other one having a high or very high current gain (GD) which can, but not necessarily, be controlled. Suitably the input class AB operating input stage (1) of this amplifier provides two pairs or one pair of antiphase output currents (IR and IL), apt to be used to feed both halves (2a, 2b) of the intermediate stage.

Abstract: In a wide dynamic range and with constant transconductance (Gm) differential voltage-to-current converter, operating in class AB, essentially comprising two complementary pairs of transistors, respectively of pnp (Q1, Q2) and npn (Q3, Q4) type, and two nominally equal resistors (RE1 and RE2), the emitters of the first pair transistors (Q1, Q2) are connected to the respective ones of dse second pair transistors (Q3, Q4) through the two resistores (E) having equal nominal resistance; a junction is provided between the emitters of the second pair transistors (Q3, Q4); and input voltages (V1 and V2) are respectively applied to the bases of first pair transistors (Q1, Q2), from collectors of which transistor output currents (I1, I2) are taken. Preferably, in this differential voltage-to-current converter, biasing and thermal balancing circuits (VP1, VP2) are connected to the first (Q1, Q3) and, respectively, to the second (Q2, Q4) transistors of said two pairs of transistors.