Operational amplifier employing complementary field-effect transistors
First Claim
1. An amplifying circuit comprising:
- first and second supply terminals for receiving relatively positive and relatively negative operating potentials, respectively;
inverting and non-inverting input terminals for receiving input signals thereat, and a signal output terminal;
a first differential-input amplifier means including;
first and second field-effect transistors, of P-channel conductivity type and in long-tailed pair connection, having respective gate electrodes to which said inverting and non-inverting input terminals respectively connect, having respective source electrodes connected to a tail connection, and having respective drain electrodes,means for supplying a first tail current connected between the tail connection of said first differential-input amplifier means and said first supply terminal,first current mirror amplifying means having an input and an output connection, and having a common connection to which said second supply terminal connects,means for connecting the input connection of said first current mirror amplifying means to the drain electrode of said first transistor, andan output connection of said first differential-input amplifier means at which output resistance is exhibited responsive to the connections of the output connection of said first current mirror amplifying means and the drain electrode of said second transistor thereto;
a second differential-input amplifier including;
third and fourth field-effect transistors, of N-channel conductivity type and in long-tailed pair connection, having respective gate electrodes to which said inverting and non-inverting input terminals respectively connect, having respective source electrodes connected to a tail connection, and having respective drain electrodes,means for supplying a second tail current connected between the tail connection of said second differential-input amplifier means and said second supply terminal;
second current mirror amplifying means having an input and an output connection, and having a common connection to which said first supply terminal connects,means for connecting the input connection of said second current mirror amplifying means to the drain-electrode of said third transistor, andan output connection of said second differential-input amplifier means at which output resistance is exhibited responsive to the connections of the output connection of said second current mirror amplifying means and the drain electrode of said fourth transistor thereto;
output amplifier means includingfirst and second input connections for providing respective relatively high resistances as compared to the output resistances of the output connections of said first and second differential-input amplifier means, respectively, andfifth and sixth field-effect transistors of N-channel and P-channel type, respectively, each in common-source amplifier configuration having respective source electrodes directly connected to said second and first supply terminals respectively having respective drain electrodes connected to said signal output terminal, and having respective gate electrodes serving as the first and second input connections, respectively, of said output amplifier means;
means for directly connecting the output connection of said first differential-input amplifier means to the first input connection of said output amplifier means without substantially reducing the resistance exhibited thereat; and
means for directly connecting the output connection of said second differential-input amplifier means to the second input connection of said output amplifier means without substantially reducing the resistance exhibited thereat.
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Accused Products
Abstract
An operational amplifier includes first and second differential-input amplifiers of complementary conductivity type, each such differential-input amplifier including first and second transistors in long-tailed pair configuration having their drains connected to third and fourth transistors connected in current mirror amplifier configuration. An output amplifier includes a pair of complementary conductivity type transistors, each in common-source configuration, to supply signals to an output terminal. One output of the long-tailed pair and the output connection of the current mirror amplifier in the first differential-input amplifier directly connect to the gate of the first common-source amplifier. One output connection of the long-tailed pair and the output connection of the current mirror amplifier of the second differential-input amplifier directly connect to the gate input of the other common-source amplifier. A tail current supply for each long-tailed pair establishes its quiescent operating point.
57 Citations
11 Claims
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1. An amplifying circuit comprising:
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first and second supply terminals for receiving relatively positive and relatively negative operating potentials, respectively; inverting and non-inverting input terminals for receiving input signals thereat, and a signal output terminal; a first differential-input amplifier means including; first and second field-effect transistors, of P-channel conductivity type and in long-tailed pair connection, having respective gate electrodes to which said inverting and non-inverting input terminals respectively connect, having respective source electrodes connected to a tail connection, and having respective drain electrodes, means for supplying a first tail current connected between the tail connection of said first differential-input amplifier means and said first supply terminal, first current mirror amplifying means having an input and an output connection, and having a common connection to which said second supply terminal connects, means for connecting the input connection of said first current mirror amplifying means to the drain electrode of said first transistor, and an output connection of said first differential-input amplifier means at which output resistance is exhibited responsive to the connections of the output connection of said first current mirror amplifying means and the drain electrode of said second transistor thereto; a second differential-input amplifier including; third and fourth field-effect transistors, of N-channel conductivity type and in long-tailed pair connection, having respective gate electrodes to which said inverting and non-inverting input terminals respectively connect, having respective source electrodes connected to a tail connection, and having respective drain electrodes, means for supplying a second tail current connected between the tail connection of said second differential-input amplifier means and said second supply terminal; second current mirror amplifying means having an input and an output connection, and having a common connection to which said first supply terminal connects, means for connecting the input connection of said second current mirror amplifying means to the drain-electrode of said third transistor, and an output connection of said second differential-input amplifier means at which output resistance is exhibited responsive to the connections of the output connection of said second current mirror amplifying means and the drain electrode of said fourth transistor thereto; output amplifier means including first and second input connections for providing respective relatively high resistances as compared to the output resistances of the output connections of said first and second differential-input amplifier means, respectively, and fifth and sixth field-effect transistors of N-channel and P-channel type, respectively, each in common-source amplifier configuration having respective source electrodes directly connected to said second and first supply terminals respectively having respective drain electrodes connected to said signal output terminal, and having respective gate electrodes serving as the first and second input connections, respectively, of said output amplifier means; means for directly connecting the output connection of said first differential-input amplifier means to the first input connection of said output amplifier means without substantially reducing the resistance exhibited thereat; and means for directly connecting the output connection of said second differential-input amplifier means to the second input connection of said output amplifier means without substantially reducing the resistance exhibited thereat. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification