Design And Implementation Of The Multi-phase Digital DC-DC Control Chip

With the rapid development of 5G communication,artificial intelligence,cloud computing and big data technology,the high-power density electronic device has higher requirements for the switching power supply.The switching power supply is gradually developing with higher frequency,polyphase,and digitalization.Compared with analog control,digital control has stronger modularity,intelligence and flexibility.Therefore,since the digital control scheme was proposed,major power companies and semiconductor chip companies have developed their digital control power supply products,which has promoted the development of the digital power supply.The dissertation mainly designs and implements a multi-phase digital DC-DC control chip.The chip is designed based on 32-bit CPU core-CK802.It not only has soft start and current sharing functions,but also can be programmed to maximize the flexibility of the digital power supply.The dissertation focuses on four key blocks: the digital filter(DPID),the high-precision digital pulse width modulator(DPWM),the digital current sharing controller and the soft start technology.The DPID block adopts a parallel independent structure.And through zero pole compensation,the compensation network parameters are determined to improve the loop stability and transient performance;the DPWM adopts a novel all-digital structure.Based on the synchronous design flow,it avoids the use of the RS flip-flop.The proposed chip integrates multi-phase interleaving function.And the chip finally achieves a DPWM output of up to 2MHz switching frequency and 250 ps resolution;the digital current sharing controller is designed based on two current sharing control methods of adjusting DPWM or DAC.Its structure and parameters designed by analyzing the small-signal model of the current loop,which can guarantee the loop stability.After designing the voltage loop and current sharing loop of the chip,the soft-start technology is implemented to avoid voltage overshoot based on the software method.The simulation results show that the voltage control loop has good stability.The current sharing control circuit achieves high current sharing accuracy.The current sharing error is less than 5% under light and heavy loads.And after adopting the soft start technology,the output voltage does not overshoot.The multi-phase digital DC-DC controller chip is designed and fabricated with the 0.18?m CMOS process.Test results show that the chip can achieve 0.6V-3.3V output voltage by adjusting the reference voltage.The chip has overcurrent protection and soft start functions.The load regulation of the chip is 1%,and the linear regulation of the chip is 0.21%.The DPWM outputs pulse with 250 ps resolution and up to 2MHz switching frequency.