Operationally amplifying method and operational amplifier

An operational amplifier for amplifying an input signal, the operational amplifier comprising:

• an amplifier which amplifies the input signal to produce an amplified signal;
• an idling current provider which provides a constant current;
• and
• a driver which outputs an output signal based on the sum of the amplified signal and the constant current,
• wherein said driver functions in a class A amplification mode when said amplified signal is less than or equal to said constant current, and functions in a class B amplification mode when said amplified signal is greater than said constant current.

An operational amplifier, comprising:

• an amplifier which amplifies an input signal into an amplified, non-inverted current signal and an amplified, inverted current signal,
• an idling current provider which provides a constant current signal;
• and
• a driver outputting an output signal, said driver including a pair of transistors, one of said transistors being driven by a voltage based on the sum of said amplified, non-inverted current signal and said constant current signal, and said other transistor being driven by a voltage based on the sum of said amplified, inverted current signal and said constant current signal, wherein said pais of transistors are driven at the same time.