Low-voltage reference buffer with wide output voltage and current range

A reference buffer comprising:

• an error amplifier comprising a first input, a second input, and a first output, wherein the amplifier is configured to generate an output signal indicative of an error between an output reference signal and an internal reference signal;
• and
• a first voltage follower circuit configured to generate the output reference signal based, at least in part, on the output signal of the error amplifier, wherein the first voltage follower comprises:
• a third input;
• a second output, wherein the second output is coupled to the second input of the error amplifier;
• a first transistor configured to receive the output signal of the error amplifier at the third input of the first voltage follower, wherein the first transistor comprises a first gate, first source, and first drain, wherein the first gate of the first transistor is the third input of the voltage follower, wherein the first gate is coupled to the first output of the error amplifier, wherein the first source is coupled to the second output of the first voltage follower;
• a second transistor coupled to the first transistor, wherein the second transistor comprises a second gate, second drain, and second source, wherein the second drain of the second transistor is coupled to the first source of the first transistor, and the second gate of second transistor is coupled to the first drain of the first transistor;
• and
• a third transistor coupled to the first transistor, the third transistor comprising a third gate, third source, and third drain, wherein the third drain of the third transistor is coupled to the first drain of the first transistor.

An analog to digital converter comprising:

• a reference buffer configured to generate an output reference signal, the reference buffer comprising:
• an error amplifier comprising a first input, a second input, and a first output, wherein the amplifier is configured to generate an output signal indicative of an error between an output reference signal and an internal reference signal;
• a first voltage follower circuit configured to generate the output reference signal based, at least in part, on the output signal of the error amplifier, wherein the first voltage follower comprises:
• a third input;
• a second output, wherein the second output is coupled to the second input of the error amplifier;
• a first transistor configured to receive the output signal of the error amplifier at the third input of the first voltage follower, wherein the first transistor comprises a first gate, first source, and first drain, wherein the first gate of the first transistor is the third input of the voltage follower, wherein the first gate is coupled to the first output of the error amplifier, wherein the first source is coupled to the second output of the first voltage follower;
• a second transistor coupled to the first transistor, wherein the second transistor comprises a second gate, second drain, and second source, wherein the second drain of the second transistor is coupled to the first source of the first transistor, and the second gate of second transistor is coupled to the first drain of the first transistor;
• and
• a third transistor coupled to the first transistor, the third transistor comprising a third gate, third source, and third drain, wherein the third drain of the third transistor is coupled to the first drain of the first transistor;
• and
• a digital to analog converter coupled to the reference buffer, and configured to receive the output reference voltage.