Low offset push-pull amplifier

An amplifier comprising a driver stage and an output stage coupled in cascade between an input terminal and an output terminal of the amplifier;

• said output stage comprising a first control circuit element, comprising an npn transistor, having three terminals and a second control circuit element, comprising a pnp transistor, having three terminals, with first terminals of the first and second control circuit elements coupled together to the output terminal of the amplifier, and with second terminals of the first and second control circuit elements coupled across a voltage supply;
• said driver stage having two output terminals coupled, respectfully, to the third terminals of the first and second control circuit elements;
• wherein said driver stage comprises;
• a current-mirror circuit having an input branch comprising a third control circuit element comprising a pnp transistor having three terminals and an output branch comprising a fourth control circuit comprising an npn transistor element having three terminals,
• a first constant current generator,
• a second constant current generator,
• a fifth control circuit element comprising a pnp transistor having three terminals, and a sixth control circuit element comprising an npn transistor having three terminals,
• wherein the first and second terminals of the third control circuit element are connected in series with the first constant current generator, the second terminals of the fifth and sixth control circuit elements are connected together to the output terminal of the amplifier, the first terminals of the fifth and sixth control circuit elements are connected, respectively to the second constant current generator and to the second terminal of the fourth control circuit element, and the third terminals of the fifth and sixth control circuit elements are connected together to the input terminal of the amplifier.

An amplifier comprising:

• a driver stage and an output stage connected in cascade so as to provide negligible offset,
• said driver stage and output stage coupled between an input terminal and output terminal of the amplifier:
• said output stage including first npn transistor and second pnp transistor, means coupling the first and second transistors in a push-pull arrangement with one another and between first and second voltage supply lines, and means inter-coupling a common terminal of the first and second transistors to the output terminal of the amplifier;
• said driver stage comprising,
• a current mirror circuit comprising an input branch including a third pnp transistor and an output branch including a fourth npn transistor
• a first constant current generator,
• a second constant current generator,
• a pair of drive transistors comprising a fifth pnp transistor and sixth npn transistor coupled in a push-pull configuration,
• means coupling the input terminal of the amplifier to like input terminals of the drive transistors,
• means coupling the current mirror circuit input branch in a first series branch with the first constant current generator, and
• means coupling in a second series branch the current mirror circuit output branch, the pair of drive transistors and the second constant current generator;
• wherein said fifth pnp transistor is connected to the first voltage supply line by the second constant-generator and the sixth npn transistor is connected to the second voltage supply line by the current mirror circuit output branch.

An amplifier comprising a driver stage and an output stage connected in cascade between an input terminal and an output terminal of the amplifier,

• the output stage comprising a first npn transistor and a second pnp transistor, connected in a push-pull arrangement with one another, with their emitters connected together to the output terminal of the amplifier and with their collectors connected, respectively, to a first supply terminal and to a second supply terminal of the amplifier, which are intended to be connected, respectively, to the positive and negative poles of a supply,
• the driver stage having two output terminals connected, respectively to the base of the first transistor and to the base of the second transistor,
• wherein the driver stage comprises a current-mirror circuit having an input branch comprising a third npn transistor connected in series with a first constant-current generator between the first and second supply terminals and an output branch comprising a fourth pnp transistor, as well as a fifth pnp transistor and a sixth npn transistor with their collectors connected together to the output terminal of the amplifier and the bases connected together to the input terminal of the amplifier, the sixth transistor having its emitter connected to the second supply terminal by means of a second constant-current generator and the fifth transistor having its emitter connected to the first supply terminal by means of the output branch of the current-mirror circuit, the emitters also being connected, respectively, to the base of the second transistor and to the base of the first transistor.

An amplifier comprising a driver stage and an output stage coupled in cascade between an input terminal and an output terminal of the amplifier;

• said output stage comprising a first control circuit element, comprising an npn transistor, having three terminals and a second control circuit element, comprising a pnp transistor, having three terminals, with first terminals of the first and second control circuit elements coupled together to the output terminal of the amplifier, and with second terminals of the first and second control circuit elements coupled across a voltage supply;
• said driver stage having two output terminals coupled, respectfully, to the third terminals of the first and second control circuit elements;
• wherein said driver stage comprises;
• a current-mirror circuit having an input branch comprising a third control circuit element comprising an npn transistor having three terminals and an output branch comprising a fourth control circuit comprising a pnp transistor element having three terminals,
• a first constant current generator,
• a second constant current generator,
• a fifth control circuit element comprising a pnp transistor having three terminals,
• and a sixth control circuit element comprising an npn transistor having three terminals,
• wherein the first and second terminals of the third control circuit element are connected in series with the first constant current generator, the second terminals of the fifth and sixth control circuit elements are connected together to the output terminal of the amplifier, the first terminals of the sixth and fifth control circuit elements are connected, respectively to the second constant current generator and to the second terminal of the fourth control circuit element, and the third terminals of the sixth and fifth control circuit elements are connected together to the input terminal of the amplifier.

An amplifier comprising:

• a driver stage and an output stage connected in cascade so as to provide negligible offset,
• said driver stage and output stage coupled between an input terminal and output terminal of the amplifier:
• said output stage including first npn transistor and second pnp transistor, means coupling the first and second transistors in a push-pull arrangement with one another and between first and second voltage supply lines, and means inter-coupling a common terminal of the first and second transistors to the output terminal of the amplifier;
• said driver stage comprising,
• a current mirror circuit comprising an input branch including a third npn transistor and an output branch including a fourth pnp transistor
• a first constant current generator,
• a second constant current generator,
• a pair of drive transistors comprising a fifth pnp transistor and sixth npn transistor coupled in a push-pull configuration,
• means coupling the input terminal of the amplifier to like input terminals of the drive transistors,
• means coupling the current mirror circuit input branch in a first series branch with the first constant current generator, and
• means coupling in a second series branch the current mirror circuit output branch, the pair of drive transistors and the second constant current generator;
• wherein said fifth pnp transistor is connected to the first voltage supply line by the current mirror circuit output branch and the sixth npn transistor is connected to the second voltage supply line by the second constant current generator.