MOS operational amplifier with current mirroring gain and method of operation

A method comprising:

• receiving a differential input signal and providing a first output signal and a second output signal in response thereto;
• coupling the first output signal to a current mirror for providing a control signal;
• coupling the second output signal to both a gain boosting stage for biasing the gain boosting stage and to a driver stage;
• coupling the control signal to both the gain boosting stage for biasing the gain boosting stage and to the driver stage;
• generating within the driver stage first and second input signals for the gain boosting stage;
• amplifying the first and second input signals within the gain boosting stage to generate first and second output signals with a predetermined gain;
• and
• using the first and second output signals to drive an output stage and provide an output voltage at an output terminal.

An amplifier comprising:

• an input stage for receiving a differential input signal and providing a first output and a second output;
• a current mirror having an input coupled to the first output of the input stage and having an output for providing a first control signal;
• a gain boosting stage having a first section and a second section, each of the first section and the second section comprising first and second pluralities of series-coupled transistors of first and second opposite conductivities, all transistors of a first conductivity of the first section being biased by one of first and second bias signals, all transistors of a second conductivity of the second section being biased by one of third and fourth bias signals, the gain boosting stage having a first input, a second input, and an output, the first input of the first section being coupled to the second output of the input stage, the second input of the first section comprising a first node between a source and a drain of a first pair of series-coupled transistors, the first input of the second section being coupled to the output of the current mirror, the second input of the second section comprising a second node between a source and a drain of a second pair of series-coupled transistors;
• a pre-driver stage having a first input coupled to the second output of the input stage, a second input coupled to the output of the first section of the gain boosting stage, a third input coupled to the output of the current mirror, a fourth input coupled to the output of the second section of the gain boosting stage, a first output coupled to the second input of the first section of the gain boosting stage, a second output, a third output coupled to the second input of the second section of the gain boosting stage, and a fourth output;
• and
• an output stage having a first input coupled to the second output of the pre-driver stage, a second input coupled to the fourth output of the pre-driver stage, and an output for providing an output signal.