Output stage of operational amplifier and method in the operational amplifier

An operational amplifier comprising:

• an input stage;
• an output stage communicatively coupled to the input stage, wherein the output stage comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, and a first current source,
• a third node of the fifth transistor and a third node of the third transistor are connected to a power supply (Vdd), a second node of the first transistor is connected to the input stage and connected to a second node of the second transistor;
• a third node of the first transistor and a first node of the first current source, and a third node of the second transistor are connected to ground (gnd), both a second node and a first node of the fourth transistor are connected to the second node of the fifth transistor;
• a first node of the second transistor is connected to a first node of the third transistor and configured to output voltage (vo);
• a second node of the third transistor is connected to a connection point between the first node of the first current source and a first node of the fifth transistor;
• and
• both a first node and a second node of the fourth transistor are connected to both a second node of the fifth transistor and a first node of the first transistor;
• wherein the operational amplifier further comprises a sixth transistor, wherein
• the sixth transistor is connected in serial between the first node of fifth transistor and the first node of the first current source, and a connection point between the first node of the first current source and a second node of the sixth transistor is connected to a first node of the sixth transistor.

A method in an operational amplifier, wherein the operational amplifier comprises:

• an input stage;
• an output stage communicatively coupled to the input stage, wherein the output stage further comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a first current source, a fifth transistor, a sixth transistor and a second current source,
• wherein a second node of the first transistor is connected to the input stage (vin), a third node of the first transistor is connected to a third node of the fourth transistor, ground (gnd), a third node of the fifth transistor and a third node of the third transistor, a first node of the first transistor is connected to a first node of the first current source, second node of the sixth transistor and a second node of the second transistor;
• a third node of the sixth transistor and second node of the second current source, a second node of the first current source, and a third node of the second transistor are connected to a power supply (Vdd);
• a first node of the second transistor is connected to a first node of the third transistor and configured to output voltage (vo);
• a second node of the third transistor is connected to a connection point between a first node of the fifth transistor and a first node of the second current source;
• and
• both a first node and a second node of the fourth transistor are connected to both second node of the fifth transistor and a first node of the sixth transistor;
• wherein the method comprises
• receiving, by the input stage, input voltage;
• and
• outputting, by a connection point of the first node of the second transistor and the first node of the third transistor, the output voltage, wherein the second transistor is always on.

A method in an operational amplifier, wherein the operational amplifier comprises:

• an input stage;
• an output stage communicatively coupled to the input stage, wherein the output stage comprises first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, and a first current source,
• a third node of the fifth transistor and a third node of the third transistor are connected to a power supply (Vdd), a second node of the first transistor is connected to the input stage and connected to a second node of the second transistor;
• a third node of the first transistor and a first node of the first current source, and a third node of the second transistor are connected to ground (gnd), both a second node and a first node of the fourth transistor are connected to the second node of the fifth transistor;
• a first node of the second transistor is connected to a first node of the third transistor and configured to output voltage (vo);
• a second node of the third transistor is connected to a connection point between the first node of the first current source and a first node of the fifth transistor;
• and
• both a first node and a second node of the fourth transistor are connected to both a second node of the fifth transistor and a first node of the first transistor;
• wherein the method comprises
• receiving, by the input stage, input voltage;
• and
• outputting, by a connection point of the first node of the second transistor and the first node of the third transistor, the output voltage, wherein the second transistor is always on.