Voltage Regulator Pole Shifting Method and Apparatus

A voltage regulator, comprising:

• a common-source output stage configured to drive a capacitive load with a regulated voltage responsive to a signal applied to the common-source output stage, the capacitive load setting the dominant pole of the voltage regulator;
• a first amplifier stage configured to amplify the difference between the regulated voltage and a reference voltage;
• a second amplifier stage configured to drive the common-source output stage with a signal corresponding to the difference between the regulated voltage and the reference voltage;
• and
• means for reducing the output resistance of the second amplifier stage to shift a non-dominant pole of the voltage regulator set by the second amplifier stage.

A method of operating a voltage regulator having first and second amplifier stages and a common-source output stage, the method comprising:

• driving a capacitive load with a regulated voltage output by the common-source output stage responsive to a signal applied to the common-source output stage, the capacitive load setting the dominant pole of the voltage regulator;
• amplifying the difference between the regulated voltage and a reference voltage applied to the first amplifier stage;
• driving the common-source output stage with a signal output by the second amplifier stage corresponding to the difference between the regulated voltage and the reference voltage;
• and
• reducing the output resistance of the second amplifier stage to shift a non-dominant pole of the voltage regulator set by the second amplifier stage.

A method of operating a voltage regulator having multiple amplifier stages and a common-source output stage, the method comprising:

• applying an amplified signal provided by the amplifier stages to the common-source output stage;
• driving a capacitive load with a regulated voltage provided by the common-source output stage responsive to the amplified signal, the capacitive load setting the dominant pole of the voltage regulator;
• and
• increasing the transconductance of the amplifier stage coupled to the common-source output stage to shift a non-dominant pole of the voltage regulator set by that amplifier stage.