Research On Low Power Consumption Modulation Circuit Of Transmitting Part Of Isolated Driver

Compared with non-isolated driver,GaN driver chips with isolated structures have stronger anti-interference ability in high-frequency applications.The isolated driver chip needs to add a transmitting circuit and a receiving circuit to realize the signal transmission on the isolation medium,and the transmitting circuit increases the power consumption of the chip.The increase in power consumption will bring about problems such as heat dissipation and circuit performance degradation.Therefore,it is extremely important to study the low-power modulation technology of the transmission part of the isolated driver.In this thesis,the three isolation methods and the corresponding modulation technology,namely optocoupler isolation,electromagnetic isolation and capacitive isolation,are analyzed and expounds the advantages of capacitive isolation in high-frequency and high-voltage applications of GaN isolation driver.Then,the source of power consumption of the modulation circuit of the capacitor-isolated drive chip was studied.It was found that the power consumption can be reduced by controlling the working state of the oscillator and changing the modulation method.A low-power modulation scheme is proposed,which can adaptively select a suitable modulation scheme according to the frequency of the input signal to achieve the purpose of low-power modulation.When the frequency of the input signal is higher than the judgment frequency,the on-off key modulation method is adopted.When the frequency of the input signal is lower than the judgment frequency,the edge modulation method is adopted.The two modulation methods are realized on the same channel,which saves chip area and controls the oscillator is only turned on during the modulation process,which avoids the problem of increased power consumption due to long-term operation of the oscillator.The low-power modulation circuit of the transmission part of the isolated driver chip designed in this paper adopts the CSMC 0.18?m BCD process for circuit design,pre-simulation and post-simulation.The post-simulation results show that the circuit realizes the function of adaptively selecting different modulation methods according to the frequency of the input signal under different process angles,and in the worst case(the SS corner),when the frequency of the input signal is 500 k Hz,the working current of the modulation circuit is137.9?A;when the frequency of the input signal is 5MHz,the working current of the modulation circuit is214.6?A,and the transmission delay of the circuit is 3.5ns,which meets the design index requirements.