| Single inductor multiple output (SIMO) DC-DC converter has been a popular research direction due to its characteristic in reducing off-chip component. In spite of its advantage in reducing volume of power management compare to conventional single inductor single output buck DC-DC, the issues with high output voltage ripple, relative low efficiency and cross regulation remains to be settled. In this paper, a single inductor double output (SIDO) synchronous rectifier buck DC-DC is designed, and some meaningful work has been done in both system modeling and circuit implementation.First of all, a DLL based ZVS driver for synchronous rectifier buck DC-DC is designed. The design has been tapeout and the test results shows an advantage of accuracy over other kinds of ZVS driver and an advantage of power consumption over other DLL based ZVS driver.Second, the working principle of SIMO buck DC-DC is analyzed in system level. The transfer functions of steady state and AC small signal are derived; the inductor current ripple and output voltage ripple are estimate; the power losses are calculated and a summary is given.Then, the design of SIMO buck DC-DC is discussed in detail. The content includes:defining the specification of the system and the main parameters of components; analyzing the close loop in frequency domain in Matlab and verified it with transient simulation in PSIM; designing the circuits for performence improvement. The closed loop design has been tested. The SIDO buck DC-DC works at 8MHz switching frequency and 2.7-4.2V input range. The overall line regulation and load regulation are both less than 25mV.The load response to either output current from 50mA to 500mA and from 500mA to 50mA shows a overshoot of about 20mV and a recovery time of about 50usThe simulation result of power efficiency shows a peak efficiency reach 85% at 600mA total current condition. The efficiency is higher than 80% when the load current is higher than 250mA.At 10mA condition, the efficiency is about 70%...
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