Differential amplifier for sensing small signals

Claim 2

A sensing circuit comprising a differential amplifier having means for receiving differential input signals and means for producing differential output signals, and an alternating current coupled feedback circuit including means for providing a latched operation coupled from said output signals producing meaNs to said input signals receiving means, said latched operation providing means including a control device having a control electrode, means for applying a predetermined bias signal to said control electrode and means for isolating the bias signal from said output signals producing means.

Claim 3

A sensing circuit as set forth in claim 1 wherein said feedback circuit includes a voltage source means and said control device couples said voltage source means to said input signals receiving means.

Claim 4

A sensing circuit as set forth in claim 2 wherein said control device includes a field effect transistor, said control electrode is a gate electrode and said bias signal isolating means is a capacitor.

Claim 5

A sensing circuit as set forth in claim 2 wherein said voltage source means provides a voltage of predetermined magnitude during a first periodic interval and a substantially zero voltage during a second periodic interval.

Claim 6

A sensing circuit as set forth in claim 4 further including means for producing signals in memory cells, means for periodically applying said memory cell signals to said input signals receiving means and means coupled to said input signals receiving means for restoring said memory cell signals into said memory cells during said second periodic interval.

Claim 7

An amplifier comprising first and second controlled current sources having first and second terminals, said first terminals having a common fixed potential, first and second input dependent current sources each having an input electrode, a constant current source coupled through said first input dependent current source to the second terminal of said first controlled current source and through said second input dependent current source to the second terminal of said second controlled current source, first and second alternating current coupled feedback circuits coupled between the second terminal of said first and second controlled current sources and the input electrode of said first and second input dependent current sources, and means for applying differential signals to said input dependent current sources.

Claim 8

An amplifier comprising first and second controlled current sources having first and second terminals, said first terminals having a common fixed potential, first and second input dependent current sources each having an input electrode, a constant current source coupled through said first input dependent current source to the second terminal of said first controlled current source and through said second input dependent current source to the second terminal of said second controlled current source, first and second alternating current coupled feedback circuits coupled between the second terminal of said first and second controlled current sources and the input electrode of said first and second input dependent current sources, and means for applying differential signals to said input dependent current sources.

Claim 9

An amplifier as set forth in claim 6 wherein each of said feedback circuits includes means for providing a voltage, a transistor, having a control electrode, coupling said voltage providing means to said signals applying means and means coupled to said second terminal of said first and second controlled current sources for applying an alternating current signal to said control electrode to set said amplifier in a latched state.

Claim 10

An amplifier as set forth in claim 7 wherein said voltage providing means applies voltage to said transistor during first predetermined periods and means for applying a bias voltage to said control electrodes.

Claim 11

An amplifier as set forth in claim 8 wherein said voltage providing means provides a substantially zero voltage at second predetermined periods.

Claim 12

An amplifier as set forth in claim 9 wherein said means for applying differential signals includes memory cells and bit lines coupling said memory cells to said input dependent current sources.

Claim 13

Amplifier amplifier as set forth in claim 10 further including means coupled to said signals apply means for restoring said signals into said cells during said second predetermined periods.

Claim 14

An amplifier as set forth in claim 7 wherein said transistor is a field effect transistor and said control electrode is a gate electrode and said alternating current signal applying means is a capacitor.

Claim 15

An amplifier as set forth in claim 12 wherein said input dependent current sources are first and second transistors having control electrodes and said signals applying means is connected to said electrodes.

Claim 16

An amplifier as set forth in claim 13 wherein said first and second transistors are field effect transistors and said control electrodes are gate electrodes.

Claim 17

An amplifier as set forth in claim 13 wherein said controlled current sources include third and foUrth transistors having control electrodes and means for applying predetermined fixed voltages to the control electrodes of said third and fourth transistors.

Claim 18

An amplifiers as set forth in claim 15 wherein said third and fourth transistors are field effect transistors having source electrodes, said control electrodes are gate electrodes and said voltages applying means includes first and second charged capacitors connected between the gate and source electrodes of said third and fourth transistors, respectively.

Claim 19

A sensing circuit comprising a constant current sink, a constant voltage source, first and second serially connected transistors coupling said constant voltage source to said constant current sink, said second transistor being interposed between said first transistor and said constant current sink, each of said transistors having a gate electrode, third and fourth serially connected transistors coupling said constant voltage source to said constant current sink, said fourth transistor being interposed between said third transistor and said constant current sink, said third and fourth transistors having gate electrodes, a first alternating current feedback circuit coupled to the common point between said first and second transistors, a second alternating current feedback circuit coupled to the common point between said third and fourth transistors, a first capacitor connected between the gate electrode of said first transistor and the common point between said first and second transistors, a second capacitor connected between the gate electrode of said third transistor and the common point between said third and fourth transistors, means coupled to the gate electrodes of said first and third transistors for periodically charging said first and second capacitors, and means for applying a differential input signal between the gate electrodes of said second and fourth transistors, each of said first and second feedback circuits including a voltage source, a field effect transistor, having a gate electrode, coupling said voltage source to said input signals applying means and a capacitor coupled between one of said common points and the gate electrode of said field effect transistor and means for applying a bias voltage to the gate electrode of said field effect transistors.

Claim 20

A sensing circuit comprising a constant current sink, a constant voltage source, first and second serially connected transistors coupling said constant voltage source to said constant current sink, said second transistor being interposed between said first transistor and said constant current sink, each of said transistors having a gate electrode, third and fourth serially connected transistors coupling said constant voltage source to said constant current sink, said fourth transistor being interposed between said third transistor and said constant current sink, said third and fourth transistors having gate electrodes, a first alternating current feedback circuit coupled to the common point between said first and second transistors, a second alternating current feedback circuit coupled to the common point between said third and fourth transistors, a first capacitor connected between the gate electrode of said first transistor and the common point between said first and second transistors, a second capacitor connected between the gate electrode of said third transistor and the common point between said third and fourth transistors, means coupled to the gate electrodes of said first and third transistors for periodically charging said first and second capacitors, and means for applying a differential input signal between the gate electrodes of said second and fourth transistors, each of said first and second feedback circuits including a voltage source, a field effect transistor, having a gate electrode, coupling said voltage source to said input signals applying means and a capacitor coupled between one of said common points and the gate electrode of said field effect transistor and means for applying a bias voltage to the gate electrode of said field effect transistors.