LDO Design Based On Chopper Technology

LDO,namely Low Drop Out linear regulator. It is called a linear regulator, because the power transistor is operating in the linear region to achieve the objective of regulators. LDO, as a regulator, is belongs to the power management chip. Electronic equipment as for now, are inseparable from the power supply, whether it is the mobile phone or computer, whether it is a microprocessor chip or other integrated circuit chip system. By this reason, the equipment also cannot leave the power management chip. In order to make the power supply can be fully utilized, we need efficient power management.A LDO under this background to power supply a module of FT-DSP is designed in this article. This LDO adopts 0.13 um CMOS process, The post-layout simulation shows that it works efficiently. The main work of this article as below:Firstly, the author classified the power supply chip and related to each kind of classification are defined. So the LDO power management chip taxonomic position is specific. Then this article summarizes the LDO’s development situation at present and development trend based on review of plenty of reference material.Secondely, a detailed analysis of the basic principle of LDO is presented. and the process of dynamic regulation of LDO is also presented. At last the performance index of LDO are defined in detail.Thirdly, this paper focuses on the design of the key modules in LDO bandgap reference. At first, the paper analyzes the shortcomings of traditional bandgap reference, and improve the design from three aspect: one, it reduces the bandgap’s output voltage, make it much more lower than silicon’s energy gap voltage; two,it decreases the temperature coefficient by secondary temperature compensation, to improve the drawback of traditional bandgap which is just only at certain point is zero temperature coefficient; three, the introduction of the chopper module improves the power supply ration rejection and lowers the offset voltagae of amplifier.Thus,the LDO’s temperature coefficient will be even lower. The simulation results show that this design of the bandgap improve the traditional bandgap reference performance.Fourly, the author compensates the stability of LDO circuit. and design the overall layout of LDO. the final layout level simulation results show that the performance meets the requirements.To sum up, the main innovations as follow: the chopper module is introduced in the LDO. The introduction of the chopper module makes the LDO’s temperature coefficient much lower. The effect of chopper module towards LDO’s temperature coefficient is mainly through reducing the offset voltage of the amplify to lower temperature coefficient.