Research on ultra-low noise LDO measurement technology

Abstract

In recent years, with the increasing requirements of high-tech industry for the performance of power supply, especially for the improvement of power noise, the traditional LDO has been unable to meet the system requirements, and it is urgent to improve the system performance with ultra-low noise LDO. Ultra low noise LDO mainly supplies power for noise sensitive signal processing system, including RF, PLL / VCO, RF mixer and modulator, ADC / DAC and high-precision sensor. The power integration noise index of some systems has reached below 5µVRMS. How to evaluate the low noise level of the device is a difficult problem. The domestic LDO noise measurement mainly relies on the traditional measurement methods, which can barely measure and evaluate the conventional LDO noise in theory, but it is difficult to accurately evaluate the ultra-low noise LDO due to the limitations of measurement methods, external environment and other factors, which brings great trouble to the research, development and application of ultra-low noise LDO. How to accurately evaluate the noise index is very important for the research, development and application Yes. In view of the fact that there is no special LDO noise measuring instrument and equipment in the industry, especially the difficulty of ultra-low noise evaluation and measurement, this paper puts forward the system framework, noise measuring circuit, system design requirements and environmental requirements of ultra-low noise measurement through research. The measurement method and system framework have been successfully applied to a number of ultra-low noise LDO chips with high reference value It has certain practical significance.