Research Of Three-mode Noise Cancellation Receiver Based On Internet Of Things Application

The rapid development of the Internet of Things market in recent years has brought great convenience to the people.The industry of IoT is still in the stage of continuous improvement.The related IoT technologies and specifications must also be continuously improved to meet the growing needs.In order to adapt to the continuous development of the IoT industry,keep up with the hot times,this thesis investigates several major IoT communication technologies.The frequency bands used by NB-IoT,LoRa and e-MTC are not far apart,which greatly improves the design feasibility of three-mode receivers.Then the three-mode low noise amplifiers and receivers suitable for NB-IoT,LoRa and e-MTC,are studied in our work.The possibility of applying noise elimination technology in low noise amplifier and receiver is also studied.Low noise amplifiers have two distinct characteristics: low noise and gain,since the low noise amplifier is in the first stage of the receiver.According to the Friis formula,the noise of the first-level circuit of the receiver determines the overall noise of the receiver.In order to reduce noise,this paper presents a scheme combining noise elimination technology with Gm-boost technique.The feasibility of common-gate noise elimination technology and capacitive cross coupling technology in circuit implementation is analyzed.Besides,it is not appropriate to use inductance in low frequency band,since normally the corresponding inductor is quite large.Therefore,our work adopts no inductance structure,which greatly reduces the area of layout.The total area of the core circuit is only 0.4mm × 0.25 mm.Due to current-reuse architectures,the power consumption of low noise amplifier core circuit is within 1mW.Referring to the method of low noise amplifier,the noise cancellation technique is also applied to the three-mode receiver.This thesis presents a novel noise cancellation receiver topology,which has three paths: the main path,the auxiliary path and the feedback path.The main path implements 50 ohm matching for the RF front-end;the auxiliary path can eliminate the thermal noise caused by the matching resistance of the main path.In this paper,an extra feedback path is introduced to eliminate the baseband noise caused by the auxiliary path,so as to further reduce the overall noise.Through the schematic simulation,the simulation result basically meets the design specification.In general,the overall noise of the receiver can be reduced to less than 2dB.