The invention relates to a low-offset and fast-response
voltage-controlled
current source. In the
voltage-controlled
current source which is realized by adopting an
operational amplifier, an
input offset voltage which is larger relative to an input reference
voltage is reduced to an acceptable range through use of an automatic zeroing method, and the output error of the voltage-controlled
current source is reduced. The
slew rate of the
operational amplifier is improved by adding a sampling hold circuit so as to realize the fast response of a circuit. The low-offset and fast-response voltage-controlled current source is especially suitable for applications, such as an LED
driving circuit, requiring fast response. In addition, the input offset is reduced by adopting the automatic zeroing method, the
low input offset of the voltage-controlled current source can be realized by adopting a standard
CMOS (Complementary
Metal Oxide Semiconducotr) process, the change of the input offset along with the changes of temperature, time, illumination and
irradiation is unnecessarily considered, and the requirement on
layout matching is lower, therefore the production cost and time are reduced.