Researches On CMOS Radio-frequency Amplifiers And The Integration Between Antennas And Amplifier Circuits

Today's communication systems comprise four major modules:the digital baseband module,the mixed-signal module,the RF(radio frequency)front-end and the antenna.The RF circuits and the antennas are usually independent of each other,and they are designed based on the analog RF circuit theory and the electromagnetic field theory respectively.Then the traditional 50-?impedance is pursued by both sides for integration.However,with the development of RF communication technology,the integration method between the antenna and the RF circuit is also constantly evolved to meet the requirements of higher frequency bands and better performance.At present,CMOS technology is widely used in the design of RF circuit chips due to its advantages of low cost and high integration.In order to better realize the integration between the RF circuit and the antenna,it is necessary to master the principle of the CMOS RF integrated circuit and the antenna optimal design capability.This thesis shows the design process of the LNA(low noise amplifier)circuit and how to design the differential antenna according to the needs of the RF amplifier.In the first part,the peak f _T,peak f _MAX,and optimum noise figure NF_MIN current densities of 0.18-um CMOS MOSFETs are explored based on Cadence simulations.Then the error range of the inductor parameters provided by CMOS library is verified by means of HFSS simulations.Both simulations lay the foundation for the specific design of CMOS RF amplifier.A fully differential 2.4GHz Cascode LNA with inductive degeneration and a 2.5GHz PA are designed for CMOS retrodirective array system.The whole system chip has been fabricated and tested.A two-stage single-ended LNA circuit using the CMOS 0.18um process is designed for5G millimeter wave band.To achieve the wideband input match,the CG(common-gate)amplifier is employed as the first stage.The influence of the parallel resonant network as inter-stage matching circuit is analyzed.A 24-28GHz wideband differential LNA is designed.To achieve the bandwidth enhancement,this LNA is comprised of CG stage,Cascode stage followed by a“Buffer”stage.The capacitor cross-coupled technology and the neutralization technology are adopted to improve the gain and noise performance.The simulation results show that the power gain of the amplifier is 10.5dB,and the noise figure is 4.5?5.5dB.To achieve compact integration with differential circuits,this thesis also presents the novel differential antenna based on SIW(substrate integrated waveguide),fed by differential ports on the same side rather than the conventional opposite sides,making the integration compact and straightforward.Moreover,the proposed antennas achieve efficient common-mode rejection.Finally,the advantages brought by the integration with the antenna which is no longer based on the impedance of 50 ohms are discussed from the perspective of the RF amplifier.When the input impedance of the designed 24-28GHz differential LNA is matched to 10 ohms,the noise figure can be optimized to 3.1?4.7dB.