Reference buffer with multiple gain stages for large, controlled effective transconductance

A reference buffer amplifier comprising:

• a transconductance amplifier including a voltage input received on an input terminal and a current output provided on an output terminal, the output terminal connected in feedback to the input terminal, the transconductance amplifier including:
• a voltage gain stage coupled to the input;
• at least one transconductance stage connected to an output of the voltage gain stage;
• a plurality of current gain stages cascade-connected to an output of a last connected of the at least one transconductance stage;
• and
• a load capacitor, that controls a bandwidth of the reference buffer, one terminal of which is connected to the output terminal of the transconductance amplifier and another terminal of which is connected a node external to the transconductance amplifier.

A reference buffer comprising:

• at least one transconductance amplifier;
• and
• at least one current gain amplifier cascade-connected to the at least one transconductance amplifier;
• wherein the at least one current gain amplifier includes a current mirror having positive feedback to increase a current gain of the current gain amplifier without increasing a quiescent power of the current gain amplifier.

A reference buffer amplifier comprising:

• a differential transconductance amplifier including a voltage input received on an input terminal and a current output provided on first and second output terminals, at least one of the first and second output terminals connected in feedback to the input terminal, the transconductance amplifier including:
• a plurality of voltage gain stages connected in cascade;
• at least one transconductance stage connected to a last-connected of the plurality of voltage gain stages;
• and
• a load capacitor, connected between the first and second output terminals of the transconductance amplifier, that controls a bandwidth of the reference buffer.

A reference buffer amplifier comprising:

• a transconductance amplifier including a voltage input received on an input terminal and a current output provided on first and second output terminals, at least one of the first and second output terminals connected in feedback to the input terminal, the transconductance amplifier including:
• a voltage gain stage coupled to the input;
• at least one transconductance stage connected to the output of an voltage gain stage;
• a plurality of current gain stages cascade-connected to an output of a last connected of the at least one transconductance stage;
• and
• a load capacitor, connected between the first and second output terminals of the transconductance amplifier, that controls a bandwidth of the reference buffer.