Factors Affecting The Reference Performance

Voltage and current references are applied to analog IC broadly. The term of reference indicates that voltage and current references have better precision and stability by far than ordinary power supply. Analog IC utilizes Voltage and current references to get supply-insensitive biasing or temperature-insensitive biasing, whose performance will directly affect the performance of analog IC. In this paper, based on comparing references classified and understanding references development, band-gap voltage reference is used as a focus of study. The basic structure and principle of band-gap voltage are analyzed in theory. Moreover, VBE and correction of band-gap voltage reference are analyzed, so that the determining factors of band-gap voltage reference are concluded. In a joint of a project, a negative linear regulator design, its band-gap voltage reference is analyzed, and the corresponding layout of the negative linear regulator is fulfilled at last. How to eliminate the error caused by the process and the manufacture in a maximum extent are considered carefully during the design. By using the mature bipolar process from certain company and the exclusive SPICE model, the circuit achieves the design requirements through the simulation, and the function of the circuit is also achieved by PCB testing circuit, and its practicability then is validated further. Considering many factors adequately during the layout design, the layout which meets the design requirements is obtained through the standard design flow, and finally passed the checkout in virtue of the software Cadence. The application of a bipolar transistor as a controllable resistor to a reference circuit is presented and a novel circuit topology based on the idea is constructed. Its working principle and the factors influencing 3-transistor bandgap reference are analyzed. The principle is used to control current driving a voltage reference to improve its input regulation greatly from 95ppm/v to 0.7ppm/V and diminish its temperature coefficient greatly from 48.4ppm/℃to 10.7ppm/℃, which shows a higher order compensation performance, and realize stable reference voltage output.