Design of a low-temperature-drift low-offset amplifier

Study about how to decrease the influence of an amplifier caused by the change of temperature, and how to reduce the offset voltage by the design of territory, then a three stage amplifier which is designed under high voltage craft is presented. The structure of the amplifier and capacitances feedback are the emphasis. PMOS is used for input differential pair to reduce input noise in the first stage and second stage of the main circuit amplification. The differential structure and folded cascode structure, which can not only decrease the offset voltage and temperature drift coefficients but also obtain the larger gain, are used in these stages. The basic common source structure is used to increase the output amplitude of the whole amp circuit in the third stage, the structure has ultra-low temperature drift coefficient and a higher accuracy of the output.