Research Of High Frequency Noise Characteristics In Short-channel Mosfets

Short-channel MOSFET(Metal-Oxide Semiconductor Field-Effect Transistor)became popular in the radio frequency and millimeter-wave integrated circuit due to its high integration density,high-performance,low power and low costs.High-frequency noise model of MOSFET as the foundation of designing low noise circuits is different according to the different process technologies.Therefore,the noise modeling of new devices is later than the fabricating of new devices.With the development of down-scaling of CMOS technology for high frequency application,the optimal high frequency performance is shown to be shifted from lower moderate inversion toward weak inversion regimes.The excess noise of device changes from thermal noise to shot noise with scaling of MOSFET.And the noise equivalent models represent the high frequency noise characteristic of the device,and the model can not only guide the circuit design,but also can guide the chip maker make higher performance device.High frequency noise characteristic of short channel MOSFET is studied in this paper.It contains some parts:Based on the physical structure of 40 nm MOSFETs and by considering the drift-diffusion equation and charge conservation law,accurate physics-based unified high-frequency noise models are developed for drain-current noise,induced gate-current noise and its cross-correlation with drain-current noise under different bias conditions,which is used to describe the frequency and bias dependence of 40 nm MOSFETs from weak inversion to strong inversion regimes.Especially,the substrate noise model and effective gate overdrive is explicitly included in unified noise models to offer excellent accuracy,continuity and smoothness.Finally,based on high-frequency equivalent circuit model of short-channel MOSFET and the four noise parameters reference data of MOSFET device,the data is obtained for drain-current noise,induced gate-current noise and its cross-correlation with drain-current noise by using two-port network noise de-embedding technology.And by comparing with models data from simulation,high-frequency noise characteristic of short-channel MOSFET has been analyzed,and the result validates the practicability and accuracy of the noise-related model.