A reference buffer includes a first current mirror, a second current
mirror, a first source follower coupled in series to a branch of the
first current mirror and receiving a first initial reference voltage and
outputting a first reference voltage, a second source follower coupled in
series to a branch of the second current mirror and receiving a second
initial reference voltage and outputting a second reference voltage, and
a resistor coupled between a first node and a second node outputting the
first and second reference voltages, respectively. The first node is
disposed between the first current mirror and the first source follower
and the second node is disposed between the second current mirror and the
second source follower. The voltage difference between the first
reference voltage and the first initial reference voltage is
substantially same as that between the second reference voltage and the
second initial reference voltage.