Research On Key Technologies Of Smart GaN Power Integrated Circuits

Enhanced GaN power devices,with low on-resistance,high operating frequency,high breakdown voltage,and high operating temperature,have shown strong advantages in the pursuit of high-frequency and high-efficiency power conversion,and have been widely used in switching power supplies,new energy vehicles,data centers and other scenarios.Due to the existence of parasitic parameters in discrete GaN power circuits,it is difficult to achieve high-frequency driving of GaN power devices and rapid turn-off of overcurrent events,on the contrary,all-GaN smart power integrated circuits that integrate power devices,drive circuits,protection circuits and other functional circuits on the same substrate can minimize parasitic parameters to achieve high-speed response to overcurrent events,ensuring that GaN power devices can safely and reliably release the potential of high-frequency applications.However,in the overcurrent protection of GaN smart power integrated circuits during high-frequency switching,there is a contradiction between fast turn-off time and drain terminal overshoot voltage during fast turn-off.Therefore,it is of great significance to study the high-speed and high-reliability overcurrent shutdown circuit in all GaN integrated circuits.Based on the basic circuit unit in the P-GaN gate-enhanced GaN integrated process platform,this thesis designs an allGaN integrated overcurrent protection circuit with the goal of realizing high-frequency operation,high-speed detection,and safe shutdown.The main work is as follows:1.Study the design strategy of the basic circuit unit in the all-GaN integration on the DC performance.Analyze the requirements of GaN-based inverters on the gate width of each device under the requirements of wide output swing and low transition region,and explore the influence of channel length modulation effect on the performance of the inverter.Analyze the load modulation and tail current source modulation of a GaN-based bootstrap comparator under the requirements of wide output swing and wide comparison range.Based on the Curtice-2 current model,derive the output low level and comparison range about the load gate width and tail current source gate width.The performance model of,respectively give the optimal value selection scheme.2.Based on the short-circuit characteristics of GaN power devices and the GaN basic circuit unit,an all-GaN integrated two-stage turn-off overcurrent protection circuit is designed.Design a drain voltage detection circuit with independent blanking time to realize shielding of false triggering and high-speed,Low-loss detection of overcurrent faults;Design a two-stage turn-off circuit based on gate clamping and delayed soft shutdown to realize fast turn-off of overcurrent GaN power devices and suppress voltage overshoot.Simulation verification: the gate drive signal can be clamped from 6V to 3.98 V within 92 ns and soft turn-off can be achieved,and the peak value of overshoot voltage is reduced by 37.8% compared with hard turn-off.At the same time,for different levels of drive requirements and complex over-current scenarios,the designed over-current protection circuit has wide input compatibility and secondary correction for over-current false turn-on,so as to improve the intelligence of the IC.3.Based on the P-GaN integrated process platform,the key circuit modules of the proposed overcurrent protection are fabricated and measured.The test results show that:the maximum operating frequency of the protection circuit is 1MHz,and the delay circuit can provide an independent blanking and delay time of 90ns～114.8ns;it can realize highspeed and Low-loss detection of overcurrent faults within 42.5ns;the detection of overcurrent faults Finally,the gate driving voltage can be clamped from 6V to 3.9V within108 ns,and the fluctuation of the clamping voltage is within 1.15 V within the driving high level range of 4V～7V.