| With the constant changes in science and technology,data communication has changed the way humans interact.The millimeter wave spectrum has abundant spectrum resources and can be applied to high-speed wireless communication systems with large data fluxes.The low cost of advanced silicon-based processes is the foundation of a highly integrated system.As a key device in the transmitter,the upconverter mixer realizes the spectrum shift of the baseband signal,and its performance restricts the quality of data communication.Therefore,it is significant to design an upconversion mixer with high gain,high linearity and high image rejection.At the same time,the loss of passive components in the millimeter wave band and the low intrinsic gain of the active device make the design of the upconverter mixer extremely challenging.In this thesis,through the research of D-band up-conversion mixer,two upconverting mixers are designed based on 65 nm CMOS process,including a Gilbert mixer with negative resistance current injection structure and intermediate frequency amplifier,and a quadrature mixer with differential quadrature coupler and transformer signal synthesizer.The main research contents and contributions of this thesis are as follows:(1)The small-signal model of the Gilbert structure is analyzed in detail.After considering the rise and fall times and phase errors of the local oscillator signal,the model is modified to obtain more accurate formula of conversion gain,noise figure and linearity.In order to increase the gain of the mixer,a negative-resistance current injection structure is added to the transconductance stage output port,which solves the big contradiction that the Gilbert structure requires a small size of the switch transistor but requires a large size transconductance transistor under the common current bias condition of the transconductance stage and the switch stage.To achieve wideband matching and selfbiasing of the IF port,an intermediate frequency amplifier with resistive feedback is added to the transconductance input port.By analyzing and simulating the small-signal model in the above structure,the results show that the improved structure can effectively increase gain and reduce noise,and the linearity is also improved when setting the local oscillator power with 1 d Bm.(2)Based on the above theoretical analysis,a Gilbert mixer with a negative-resistance current injection structure and an intermediate frequency amplifier is designed to improve the gain and linearity of the mixer.In order to convert the single-ended signal of the LO and the RF port into a differential signals,the balun is designed and the impedance matching in the RF and LO ports is completed in the transmission line combination with inductance.The post-imitation results show that the maximum voltage conversion gain is 8d B,the 3d B gain bandwidth is 13 GHz,the output 1d B compression point is-6d Bm,the input third-order intercept point is-5.5d Bm,and the LO-RF isolation is greater than 40 d B.The chip size is 480 × 310 2?m after all PADs are included.(3)To achieve image rejection,an upconversion quadrature mixer was designed.A D-band differential quadrature coupler is designed at the LO port to realize four signal outputs with the phase difference of 90°.At 140 GHz,the amplitude balance is less than 0.7d B,the phase balance is less than 1 degree,and 31.4d B image rejection can be achieved.A signal synthesizer is designed on the RF port to realize the synthesis of two differential signals and convert them into a single-ended form.The post-imitation results show that the maximum conversion gain is 16 d B,the output 1d B compression point is-13.35 d Bm,the input third-order intercept point is-5.5d Bm,and the LO-RF isolation is greater than 30 d B.The chip size is 600 × 400 μm2 after all PADs are included. |
PDF Full Text Request