Research On Preamplifier Of Isolated Driver Chip Demodulation Module

With the rise of third-generation semiconductors and the higher requirements of power electronic systems for the performance of high-voltage driver chips,the research on isolated driver chips has become more and more important.Transmitter module and receiver module are included in a isolated driver chip.The preamplifier is the core circuit of the receiver module of the isolated driver chip.Receive the modulated input signal and amplify it is preamplifier’s function,and then provide the output signal to the demodulation circuit.The overall performance of the isolated driver chip is determined by preamplifier’s common-mode transient immunity,gain,bandwidth and other performance parameters,so research on preamplifiers is very important.The physical mechanism of dv/dt noise interference to the preamplifier is firstly analyzed,and the output signal of the traditional preamplifier which is lost under dv/dt noise is then explained.Therefore,the stable operation of the chip under high dv/dt noise cannot be guaranteed.In this regard,a high-voltage capacitor charging current compensation circuit,a second-stage amplifier tail current compensation circuit,and a cross-coupled common-gate amplifier circuit to eliminate the influence of dv/dt noise on the preamplifier and enhance the common-mode transient of the preamplifier are designed.The anti-interference ability solves the abnormal output of the traditional preamplifier due to dv/dt noise.In addition,the higher operating frequency and larger gain requirements of the preamplifier are needed and the high-frequency gain bandwidth characteristics of the preamplifier by designing a small-signal inductive load circuit and a source negative resistance negative feedback circuit are optimized.The pre-amplifier effectively amplifies high-frequency input signals.Based on the CSMC 0.18μm BCD process,the high-performance preamplifier is implemented in this thesis,and the circuit function simulation and the simulation of the amplifier common mode transient immunity,gain bandwidth and other performance parameters are performed.Finally,the design of the preamplifier The amplifier performs layout design and post-simulation verification.The post simulation results show that in the worst case,that is,under the ss 125℃ process angle,the common mode transient immunity of the amplifier is not less than 100V/ns,the gain is 22.39 d B at1 GHz operating frequency,and the phase margin is 48.8°.Meet the design index requirements.