Research On RF Quadrature Mixing Circuit Based On CMOS Technology

With the accelerating evolution of the digital information and the Internet of Things era,on-chip integration of high-speed wireless communication systems has become the focus of research in the industry.The continuation of Moore’s Law has driven the rapid development of CMOS technology,and the characteristic frequency of MOS transistors is constantly increasing.CMOS process has become one of the mainstream processes for RF integrated circuit design.As a key component of the RF receiver front-end,the quadrature mixing circuit achieves frequency spectrum shifting of the RF signal,and its performance directly affects the quality of wireless communication.At present,the quadrature mixing circuit with low noise,high port-toport isolation,high integration,favorable magnitude consistency and phase orthogonality is a research hotspot.Based on the 65nm CMOS process,this thesis focuses on the research of RF quadrature mixing circuit,which has academic significance and application value.The main work and innovations of this thesis are as following:1.In order to further improve the quadrature accuracy of the output signals of the quadrature mixing circuit in the presence of common-mode interference and parasitic loading,this thesis designs and implements a fully differential vertical-stacked quadrature hybrid generation network based on a high coupling coefficient transformer.Starting from a transformer-based single-ended quadrature generation network,this thesis extends its differential topology.Based on the results of odd and even mode analysis,a scaling factor is introduced to establish a quantitative relationship between the phase orthogonality frequency and the magnitude consistency frequency.This thesis derives the numerical solution of the phase quadrature mismatch at the magnitude consistency frequency and modifies the circuit design equations of a fully differential transformer-based quadrature generation network.The simulation results show that the quadrature generation network operates at the frequency range of 6.2-8.5GHz,with each port having a return loss greater than 15dB and an insertion loss of 3.45dB.The magnitude imbalance and phase quadrature mismatch of I and Q channels are less than±1dB and 0.45°,respectively.Good magnitude consistency and phase orthogonality demonstrate the feasibility of the modified equations guiding the circuit design.2.For the purpose of avoiding the loss of useful information caused by the aliasing of asymmetric signals in the direct-conversion receivers,this thesis designs and implements a single-channel quadrature mixing circuit.The signal feedthrough situation of different mixer topologies is analyzed in detail,and the generation mechanism of different types of noise in active mixers is derived hierarchically.A passive double-balanced mixer and a transimpedance amplifier are designed in this thesis.The measured results show that the power consumption of the single-channel quadrature mixing circuit is 23.8mW,and the peak conversion gain is 4.25dB when the power of the LO signal is greater than 2.3 dBm.When the frequency of the IF signal is in the range of 60-650MHz,the noise figure is 10.7-11.3dB.The magnitude imbalance and phase quadrature mismatch of the I and Q output signals are less than 1.22dB and 1.7°,respectively.3.To provide homologous differential LO signals for a dual-channel quadrature mixing circuit,ensuring high channel-to-channel isolation,good magnitude and phase consistency,this thesis designs and implements a LO power distribution network.Based on this,a dual-channel quadrature mixing circuit is proposed and implemented.The simulation results show that the power consumption of the dual-channel quadrature mixing circuit is 46mW,and the conversion gain is stable at about 2dB when the power of the LO signal is greater than 6dBm.When the frequency of IF signal is within the range of 0-650MHz,the magnitude imbalance and phase quadrature mismatch of I and Q channels are both stable below 0.35dB and less than 0.35°,respectively.