Operational amplifier
AssigneeRohm Co., Ltd.
InventorNaohiro NOMURA
Life of this patent
Estimating the term…
Abstract
An operational amplifier includes a differential input stage that amplifies a differential input signal to generate an intermediate signal; an amplification stage including an output transistor that is connected between an output terminal and a fixed voltage line, and is driven according to the intermediate signal; and an assist circuit, wherein the assist circuit includes: a first transistor connected in parallel with the output transistor; and a drive circuit that drives the first transistor according to a gate voltage of the output transistor.
Claims16
An operational amplifier comprising:
- a differential input stage that amplifies a differential input signal to generate an intermediate signal;
- an amplification stage including an output transistor that is connected between an output terminal and a fixed voltage line, and is driven according to the intermediate signal;
- and
- an assist circuit,
- wherein the assist circuit includes:
- a first transistor connected in parallel with the output transistor;
- and
- a drive circuit that drives the first transistor according to a gate voltage of the output transistor.
An operational amplifier comprising:
- a differential input stage that amplifies a differential input signal to generate an intermediate signal;
- an amplification stage including a low-side transistor that is connected between an output terminal and a ground line, and is driven according to the intermediate signal;
- and
- an assist circuit,
- wherein the assist circuit includes:
- a first transistor connected in parallel with the low-side transistor;
- a second transistor that includes a source connected to the ground line and is biased to flow a constant current;
- a third transistor that includes a gate connected to a gate of the low-side transistor and a source connected to a drain of the second transistor;
- a current mirror circuit that returns a current flowing through the third transistor to source the current to a gate of the first transistor;
- and
- a fourth transistor that includes a source connected to the ground line and a drain connected to the gate of the first transistor, and is biased to flow a constant current.
An operational amplifier comprising:
- a differential input stage that amplifies a differential input signal to generate an intermediate signal;
- an amplification stage including a high-side transistor that is connected between an output terminal and a power supply line, and is driven according to the intermediate signal;
- and an assist circuit,
- wherein the assist circuit includes:
- a first transistor connected in parallel with the high-side transistor;
- a second transistor that includes a source connected to the power supply line and is biased to flow a constant current;
- a third transistor that includes a gate connected to a gate of the high-side transistor and a source connected to a drain of the second transistor;
- a current mirror circuit that returns a current flowing through the third transistor to sink the current from a gate of the first transistor;
- and
- a fourth transistor that includes a source connected to the power supply line and a drain connected to the gate of the first transistor, and is biased to flow a constant current.
Dependencies are inferred from the claim text.