Complementary-FET driver circuitry for push-pull class B transistor amplifiers
First Claim
1. An amplifier comprising:
- a p-channel field effect transistor and an n-channel field effect transistor, each having respective gate and source and drain electrodes and having a complementary drain current versus source-to-gate potential characteristic to that of the other;
an input signal terminal at the interconnected gate electrodes of said p-channel and n-channel field effect transistors;
means applying relatively positive and relatively negative operating potentials to the source electrode of said p-channel field effect transistor and to the source electrode of said n-channel field effect transistor, respectively;
means for applying a biasing potential to said input signal terminal, which biasing potential is substantially midway between said relatively positive and relatively negative operating potentials, which includes means for direct coupling each of the drain electrodes of said p-channel and n-channel field effect transistors to said input signal terminal;
first and second output transistor means of complementary conductivity types to said p-channel field effect transistor and to said n-channel field effect transistor, respectively, each having input and output and common electrodes;
means connecting the drain electrode of said p-channel field effect transistor to the input electrode of said first output transistor means applying the drain potential of said p-channel field effect transistor to the input electrode of said first output transistor means;
means connecting the drain electrode of said n-channel field effect transistor to the input electrode of said second output transistor means for applying the drain potential of said n-channel field effect transistor to the input electrode of said second output transistor means;
means connected between the input electrodes of said first and second output transistor means for biasing them so that said first output transistor means is non-conductive during substantial negative excursions of output signal and so that said second output transistor means is non-conductive during substantial positive excursions of output signal;
means for applying relatively positive and relatively negative operating potentials to the output electrode of said first output transistor means and to the output electrode of said second output transistor means, respectively; and
an output signal terminal between the common electrodes of said first and second output transistors means, respectively.
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Abstract
A complementary or quasi-complementary Class B transistor amplifier stage, the halves of which have their output circuits serially connected between relatively negative and relatively positive operating supply voltages to receive direct current and are operated in push-pull with each other for signal to supply a common load from the interconnection of their output circuits, has driver circuitry including a pair of field effect transistors operated in push-pull to supply respective halves of the Class B transistor amplifier. A p-channel field effect transistor with source electrode connected to the relatively positive operating supply voltage drives one half of the Class B transistor amplifier stage from its drain electrode, and an n-channel field effect transistor with source electrode connected to the relatively negative operating supply voltage drives the other half of the Class B transistor amplifier stage. The field effect transistors in the driver circuitry are enhancement-mode types permitting their gate electrodes to be connected together to receive input signal potential, avoiding the need for voltage translating circuitry to secure their push-pull operation.
31 Citations
23 Claims
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1. An amplifier comprising:
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a p-channel field effect transistor and an n-channel field effect transistor, each having respective gate and source and drain electrodes and having a complementary drain current versus source-to-gate potential characteristic to that of the other; an input signal terminal at the interconnected gate electrodes of said p-channel and n-channel field effect transistors; means applying relatively positive and relatively negative operating potentials to the source electrode of said p-channel field effect transistor and to the source electrode of said n-channel field effect transistor, respectively; means for applying a biasing potential to said input signal terminal, which biasing potential is substantially midway between said relatively positive and relatively negative operating potentials, which includes means for direct coupling each of the drain electrodes of said p-channel and n-channel field effect transistors to said input signal terminal; first and second output transistor means of complementary conductivity types to said p-channel field effect transistor and to said n-channel field effect transistor, respectively, each having input and output and common electrodes; means connecting the drain electrode of said p-channel field effect transistor to the input electrode of said first output transistor means applying the drain potential of said p-channel field effect transistor to the input electrode of said first output transistor means; means connecting the drain electrode of said n-channel field effect transistor to the input electrode of said second output transistor means for applying the drain potential of said n-channel field effect transistor to the input electrode of said second output transistor means; means connected between the input electrodes of said first and second output transistor means for biasing them so that said first output transistor means is non-conductive during substantial negative excursions of output signal and so that said second output transistor means is non-conductive during substantial positive excursions of output signal; means for applying relatively positive and relatively negative operating potentials to the output electrode of said first output transistor means and to the output electrode of said second output transistor means, respectively; and an output signal terminal between the common electrodes of said first and second output transistors means, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A Class AB push-pull amplifier comprising:
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a p-channel field effect transistor and an n-channel field effect transistor of depletion-mode type, each having respective gate and source and drain electrodes and having a complementary conductivity characteristic to that of the other; means for applying relatively positive and relatively negative operating potentials to the drain electrodes of said n-channel and said p-channel field effect transistors, respectively; a further field effect transistor of enhancement-mode type having a source electrode connected to the gate electrode of the one of said depletion-mode field effect transistors of similar conductivity type to itself, having a drain electrode connected to the gate electrode of the one of said depletion-mode field effect transistors of opposite conductivity type to itself, and having a gate electrode; potential divider means for applying a fraction of the potential between the source and drain electrodes of said further field effect transistor between its source and gate electrodes; a current source means connected to the gate electrode of said n-channel field effect transistor of depletion-mode type, and a current sink means connected to the gate electrode of sad p-channel field effect transistor of depletion-mode type, at least one of said current source means and said current sink means arranged to conduct current varying in accordance with an input signal; and an output signal terminal to which the source electrodes of said p-channel and n-channel field effect transistors respectively connect. - View Dependent Claims (23)
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Specification