Operational amplifier

An operational amplifier comprising:

• M-stage differential amplifier circuits, 2≦M, each of which includes a differential pair of first and second transistors and a (M−1)th stage differential amplifier circuit of which further includes a first current source,
• the first and second transistors being provided on a side of a high voltage power source and their control electrodes receiving mutually reversed phase, positive and negative side input voltages, respectively,
• the first current source being provided between the first and second transistors and a low voltage power source to generate a first bias current;
• a replica amplifier including a differential pair of third and fourth transistors and a second current source,
• the third and fourth transistors being provided on the side of the high voltage power source and their control electrodes receiving the positive and negative side input voltages, respectively,
• the second current source being provided between the third and fourth transistors and the low voltage power source;
• a voltage-current converting circuit supplied with positive and negative side voltages output from the replica amplifier,
• the voltage-current converting circuit converting the positive and negative side voltages to output currents;
• and
• a bias current control circuit that receives the output currents from the voltage-current converting circuit, generates a differential current between the output currents and the reference current and supplies the differential current to the first current source to control the first bias current.

An operational amplifier comprising:

• M-stage differential amplifier circuits, 2≦M, each of which includes a differential pair of first and second transistors and a (M−1)th stage differential amplifier circuit of which further includes a first current source,
• the first and second transistors being provided on a side of a high voltage power source and their control electrodes receiving mutually reversed phase, positive and negative side input voltages, respectively,
• the first current source being provided between the first and second transistors and a low voltage power source to generate a first bias current;
• (M−1)-stage replica amplifiers, each of which includes a differential pair of third and fourth transistors and a second current source,
• the third and fourth transistors being provided on the side of the high voltage power source and their control electrodes receiving the positive and negative side input voltages, respectively,
• the second current source being provided between the third and fourth transistors and the low voltage power source;
• a voltage-current converting circuit supplied with positive and negative side voltages output from the replica amplifier,
• the voltage-current converting circuit converting the positive and negative side voltages to output currents;
• and
• a bias current control circuit that receives the output currents from the voltage-current converting circuit, generates a differential current between the output currents and the reference current and supplies the differential current to the first current source to control the first bias current.

An operational amplifier comprising:

• an amplifier including a differential pair of first and second transistors and a first current source,
• the first and second transistors being provided on a side of a high voltage power source and their control electrodes receiving mutually reversed phase, positive and negative side input voltages, respectively,
• the first current source being provided between the first and second transistors and a low voltage power source to generate a first bias current;
• a replica amplifier including a differential pair of third and fourth transistors and a second current source,
• the third and fourth transistors being provided on the side of the high voltage power source and their control electrodes receiving the positive and negative side input voltages, respectively,
• the second current source being provided between the third and fourth transistors and the low voltage power source;
• a current mirror circuit supplied with positive and negative side voltages output from the replica amplifier,
• the current mirror circuit converting the positive and negative side voltages to output currents;
• and
• a bias current control circuit that receives the output currents from the voltage-current converting circuit, generates a differential current between the output currents and the reference current and supplies the differential current to the first current source to control the first bias current.