Output stage of a digital to analog converter

An apparatus comprising:

• a positive voltage supply terminal;
• a negative voltage supply terminal;
• a first transconductance amplifier having a first output and a second output;
• an amplifier having a first input, a second input, and an output, the first input of the amplifier coupled to the first output of the first transconductance amplifier, the second input of the amplifier coupled to the second output of the first transconductance amplifier;
• a resistor having a first terminal and a second terminal, the first terminal of the resistor coupled to the output of the amplifier;
• and
• a second transconductance amplifier having a first input, a second input, a first output, and a second output, the first input of the second transconductance amplifier coupled to the second terminal of the resistor and the positive voltage supply terminal, the second input of the second transconductance amplifier coupled to the negative voltage supply terminal, the first output of the second transconductance amplifier coupled to the second output of the first transconductance amplifier and the second input of the amplifier, the second output of the second transconductance amplifier coupled to the first output of the first transconductance amplifier and the first input of the amplifier the second output of the first transconductance amplifier and the second input of the amplifier.

An apparatus comprising:

• a first switch having a first terminal and a second terminal;
• a second switch having a first terminal and a second terminal;
• a third switch having a first terminal and a second terminal;
• a fourth switch having a first terminal and a second terminal;
• a fifth switch having a first terminal and a second terminal, the second terminal coupled to a common terminal;
• a first transconductance amplifier having a first output and a second output, the first output of the first transconductance amplifier coupled to the second terminal of the first switch and the second terminal of the third switch, the second output of the first transconductance amplifier coupled to the second terminal of the second switch and the second terminal of the fourth switch;
• an amplifier having a first input, a second input, and an output, the first input of the amplifier coupled to the first output of the first transconductance amplifier, second terminal of the first switch, and the second terminal of the third switch, the second input of the amplifier coupled to the second output of the first transconductance amplifier, the second terminal of the second switch, and the second terminal of the fourth switch;
• a resistor having a first terminal and a second terminal, the first terminal of the resistor coupled to the output of the amplifier;
• and
• a second transconductance amplifier having a first input, a second input, a first output, and a second output, the first input of the second transconductance amplifier coupled to the second terminal of the resistor, the second input of the second transconductance amplifier coupled to the output of the amplifier and the first terminal of the resistor, the first output of the second transconductance amplifier coupled to the first terminal of the first switch, the second output of the second transconductance amplifier coupled to the first terminal of the second switch;
• and
• a third transconductance amplifier having a first input, a second input, a first output, and a second output, the first input of the third transconductance amplifier coupled to the second terminal of the resistor and the first input of the second transconductance amplifier, the second input of the third transconductance amplifier coupled to the first terminal of the fifth switch, the first output of the third transconductance amplifier coupled to first terminal of the fourth switch, the second output of the third transconductance amplifier coupled to the first terminal of the third switch.