Design And Research Of A High-frequency Rectifier Circuit Based On Isolated Power Supply

With the proposition of the concept of the IOT(Internet of Things),the "smart IOT" is increasingly used in people's life and work scenarios.Isolated power supply is used in medical equipment,electronic communication,smart home appliances and industrial monitoring because of its characteristics of energy transmission under the condition of electrical isolation.Isolated power supply has many advantages,such as good anti-interference,high isolation,small size,high integration and others.Most of the isolated power supplies have low conversion efficiency,and it is of great significance to resaerch how to improve the efficiency of isolated power supplies.This article mainly studies and designs the rectifier circuit module with high energy consumption in the isolated power supply,and further improves the power conversion efficiency of the isolated power supply through the optimization of the rectifier module.Three types of CMOS high-frequency rectifier circuits are designed using full-wave rectification technologies such as gate cross-coupling,bootstrap capacitors,dynamic body switching,and active diodes.And the three rectifier circuits are passive rectifier circuits,PMOS active rectifier circuits,and active bootstrap rectifier circuits.When the three rectifier circuits are used in isolated power systems,they can all achieve stable output.The passive rectifier circuit and the active rectifier circuit have good stability and good power conversion efficiency at high frequencies,and the PCE of this two rectifiers are 72% And 83%.The designed isolated power system consists of main energy consumption modules such as rectifier circuit,oscillator and transformer,and peripheral modules such as reference power supply,bias circuit,PWM signal and loop compensation.After the system is powered on,the oscillator generates an AC signal with a frequency of196 MHz on the primary side,which is coupled to the secondary side by a transformer,and then generates a stable DC output after CMOS full-wave rectification and loop control.The isolated power supply has two working modes of input/output of 5V/5V and 3.3V/3.3V,and the mode switching is realized by an external selection signal.In the Hspice environment,the CSMC 0.35?m BCD process library is used for overall simulation of the isolated power supply system.When three different rectifier circuits are applied to the system,the isolated power supply can achieve the target output inboth operating modes.When the load current It has better conversion efficiency when it is greater than 40 mA.The application of the isolation system derived from the rectifier circuit has the best conversion efficiency,which is about 42% and 40% respectively in the two operating modes of 5V/5V and 3.3V/3.3V,compared with the application of Schottky diode rectification The isolated power supply of the bridge has an efficiency improvement of about 7%.