Differential amplifier circuitry including: first and second main transistors of a given conductivity type: and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type; and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

A multi-stage amplifier circuit includes a pre-stage amplifier circuit and a floating control circuit. The pre-stage amplifier circuit amplifies a voltage difference between its input terminals, to generate plural pre-stage transconductance currents flowing through corresponding plural pre-stage transconductance nodes. The floating control circuit includes: a floating reference transistor configured as a source follower and a floating amplifier. The floating amplifier and the floating reference transistor are coupled to form feedback control and to generate an upper driving signal and a lower driving signal according to a floating reference level in the floating control circuit. The upper driving signal is higher than the lower driving signal with a predetermined voltage difference. The floating control circuit is electrically connected to the plural pre-stage transconductance nodes and is floating in common mode relative to the pre-stage transconductance nodes.

An amplifier circuit can be configured to receive a differential input signal having a common mode component that can extend to at least one power supply rail for the amplifier circuit. The amplifier circuit can include an input stage, such as having a first differential transistor pair, and the input stage can receive the differential input signal and in response conduct a differential first current to a cascode output stage. The cascode output stage can include or use a cascode control signal that is adjusted in response to the differential input signal. The cascode control signal can be independent of a transconductance of the first differential transistor pair. In an example, the amplifier circuit includes a slew boost circuit configured to source or sink current at an output of the amplifier based on a magnitude and polarity of the differential input signal.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type; and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

An amplifier circuit can be configured to receive a differential input signal having a common mode component that can extend to at least one power supply rail for the amplifier circuit. The amplifier circuit can include an input stage, such as having a first differential transistor pair, and the input stage can receive the differential input signal and in response conduct a differential first current to a cascode output stage. The cascode output stage can include or use a cascode control signal that is adjusted in response to the differential input signal. The cascode control signal can be independent of a transconductance of the first differential transistor pair. In an example, the amplifier circuit includes a slew boost circuit configured to source or sink current at an output of the amplifier based on a magnitude and polarity of the differential input signal.

A differential input amplification-stage circuit comprises a voltage unit, first and second bulk-driven transistors, first and second mirror current sources, and a differential amplifier unit. The first and the second bulk-driven transistors respectively receive first and second input voltages, and converts the first and the second input voltages into first and second output currents. The differential amplifier unit separately outputs first and second adjustment currents under an action of voltages output by the first to the third voltage output ends. The first and the second mirror current sources respectively output first and second predetermined currents according to the first output current and the first adjustment current, and the second output current and the second adjustment current, so as to maintain transconductance constancy of the differential input amplification-stage circuit. Therefore, output stability is improved.

An operational amplifier circuit includes: a first differential amplifier section containing a P-type differential pair of P-type transistors; a second differential amplifier section containing an N-type differential pair of N-type transistors; an intermediate stage connected with outputs of the first and second differential amplifier sections and containing a first current mirror circuit of P-type transistors, and a second current mirror circuit of N-type transistors; and an output stage configured to amplify an output of the intermediate stage in power. The first differential amplifier section includes a first current source and a first capacitance between sources of the P-type transistors of the P-type differential pair and a positive side power supply voltage. The second differential amplifier section includes a second current source and a second capacitance between sources of the N-type transistors of the N-type differential pair and a negative side power supply voltage.

An operational amplifier circuit includes: a first differential amplifier section containing a P-type differential pair of P-type transistors; a second differential amplifier section containing an N-type differential pair of N-type transistors; an intermediate stage connected with outputs of the first and second differential amplifier sections and containing a first current mirror circuit of P-type transistors, and a second current mirror circuit of N-type transistors; and an output stage configured to amplify an output of the intermediate stage in power. The first differential amplifier section includes a first current source and a first capacitance between sources of the P-type transistors of the P-type differential pair and a positive side power supply voltage. The second differential amplifier section includes a second current source and a second capacitance between sources of the N-type transistors of the N-type differential pair and a negative side power supply voltage.