The Design Of LDO In MEMS Sensor

As the development of electrical productions and diversified requirements, power management technology has become a significant criteria in modern electrical system design. Among all kinds of power management IC, Low Drop-Out linear voltage regulator has advantages over Load Regulation, Output Noise and Output Ripple.Researched the international and native development of LDO, the thesis elaborate on the rationale of LDO and performance specifications in detail. Except for basic function module, auxiliary modules are also adopted to control and protect LDO system, such as over-temperature protection, over-current protection and quick start-up circuit. And then the thesis present some circuit-level realization of core modules detailedly such as Bandgap reference, Error Amplifier and Pass transistor. High-order curvature-compensation is adopted to obtain low temperature coefficient radically. Different temperature coefficient resistors are designed to compensate nonlinearity in reference voltage, and temperature coefficient is decreased obviously. Chopper technique is also used to reduce low frequency output noise. In order to satisfy the requirement of load current and low drop-out voltage, PMOS transistor is designed. It’s worth noting that drop-out voltage of MOS transistor and system stability needs to be compromise. Pole-Zero Tracking frequency compensation used to stabilized LDO system.The system is designed in CSMC 0.5μm CMOS process, and simulated by the Spectre of Cadence. Equivalent noise is 1/222.375 n V/Hz inside1Hz~10k Hz. System Linear regulation is 65u/V,Load Regulation is 1.66 m V/A,Power Supply Rejection Ration is 83 d B@10KHz. The system is stable under 0~30m A. Finally performance specifications are satisfied.