Design, Physical Implementation And Integration Of High Resolution DPWM

PMW(pulse width modulation)is widely used in switching power supply,DC motor control,communication and other fields.In recent years,with the development of integrated circuits,the proportion of consumer electronics in the market is increasing.Digital switching power supply has gradually become a popular research direction due to its good stability,easy portability,and complex control algorithms.Digital pulse width modulator,an important module of switching power supply,also has great research value.Its linearity,switching frequency,resolution and other performance parameters directly affect the performance of switching power system.Based on the analysis of the traditional DPWM structure and the method of improving the resolution,this paper proposes a DPWM module with a three-level hybrid structure to achieve 12-bit resolution.Using the SMIC 130 nm process library,the adjustable delay cell and calibration module are built with standard cells to form a delay module.The ideal delay of the adjustable delay cell is 1.25 ns,and the ideal delay of the delay module is 10 ns.After using a 3-bit delay line structure and a 6-bit CounterComparator structure to implement Core DPWM with 9-bit resolution,a second-order Sigma-Delta modulator and digital dithering modulator were designed to extend the 3-bit resolution.Using Simulink to model two hybrid structures and simulate them in a digital DC-DC converter,it was found that the second-order Sigma-Delta modulator has better performance.At the same time,a microcontroller based on RISC-V was designed,and the DPWM module was integrated in the microcontroller as a peripheral.First,the back-end design of the adjustable delay cell,delay module,and dummy mux was carried out,then the submodule's physical library was used to complete the toplevel physical design of the DPWM module and microcontroller.During the physical design of submodule,the Manhattan distance between standard cells is adjusted manually to improve the consistency of devices.By adding shield to the signal nets,the crosstalk can be reduced effectively.After the post-simulation,it was found that the DPWM module works normally under the Typical,Slow and Fast process corner,which meets the design indicators.We accomplished the static timing analysis,formal verification,DRC check,LVS check and antenna effect check of chip.Finally,the layout of DPWM module and microcontroller was taped out.