Design Of High Linearity Current-Mode Passive Mixer For SAW-Less Receiver

In recent years,the cellular and Wi-Fi application scenarios are more extensive,and the performance requirements of SAW-Less receivers are also higher.In order to meet the high linearity requirements of SAW-Less receivers,a high linearity current-mode passive mixer for SAW-Less receiver is designed in the thesis,which can be applied to frequency division duplex system(FDD),time division duplex system(TDD)and global mobile communications(GSM)system,and has a wide range of engineering applications.The current-mode passive mixer designed in this thesis mainly includes a passive mixing switch circuit,a filterable transimpedance amplifier and a four-phase clock circuit.The thesis improves the design of the filterable transimpedance amplifier(TIA)(the core of the current mode passive mixer),which is composed of a three-stage transconductance amplifier(OTA)and passive resistance and capacitance,and integrates the channel filtering function into the impedance amplifier,the signal amplification and filtering are realized at the same time.The three-stage transconductance amplifier uses a zero compensation method instead of the traditional Miller compensation method to meet its stability requirements,and optimizes the bandwidth and gain.Four-phase clock circuit is composed of a frequency divider and a buffer to provide a local oscillator signal with a duty cycle of 25% required by a current-mode passive mixer.A master-slave trigger structure is improved in the thesis,based on the master-slave trigger,the frequency divider has lower static power consumption.In addition,the thesis presents a nonlinear analysis method for circuit-level modeling based on multi-level transconductance amplifiers.Compared with the transistor-level modeling method,this method is simpler,more effective,and more accurate.Based on the TSMC 40 nm CMOS process,specific circuits and layouts are designed and performed simulation verification in the thesis.The results show that the current-mode passive mixer’s RF input signal frequency band is 2.412 ～ 2.472 GHz and 5.15 ～ 5.825 GHz,the channel bandwidth is 20 MHz,the voltage conversion gain is 32.5d B,the noise figure is 7.7d B,the input third-order intermodulation point(IIP3)in the band is 30.2d Bm @ 5MHz,and the input third-order intermodulation point(IIP3)out of the band is 51.5d Bm @ 100 MHz,all of which meet the specifications.