| Millimeter wave(mm-wave)technology is gaining more and more important applications in wireless systems such as mobile communication and radar,and it is also a hot technology concerned by industry and academia.The key component of mm-wave communication is the mm-wave transceiver,and the frequency source technique and circuit are its core components,including oscillators,frequency multipliers and frequency dividers.However,the current frequency source circuit has problems such as high phase noise and narrow bandwidth.Compared with the compound process,the CMOS process has the advantages of low cost and easy integration and is a current research hotspot.To this end,this thesis conducts research on the key technique of mm-wave frequency sources based on CMOS technology,and carries out theoretical research and innovative design on oscillators,frequency multipliers,and frequency dividers.In addition,a radar transmitter is designed using the research results of the frequency source.The main research contents and innovations of this thesis are as follows:Ⅰ.Transformer coupled voltage-controlled oscillator(VCO)The research of VCO mainly includes two research results:1.A VCO with extra cross-coupling path.Aiming at the problems of low signal swing and high phase noise of low-power oscillator,a new cross-coupling structure is proposed based on the phase noise generation mechanism of mm-wave oscillator.Based on the conventional crosscoupling path,another cross-coupling path is introduced through the transformer,thereby enhancing the gate voltage swing of the oscillator’s cross-coupled pair and the slope of the voltage crossover point,enhancing the negative resistance performance of the cross-coupling pair,and reducing the phase noise.Based on this method,a low-power oscillator is designed with a tuning range of 6.26-8.84 GHz,only consumes 0.9 m W power consumption,and the optimal phase noise reaches-107.15 dBc/Hz.The test verifies the technical feasibility.Related results were published in IEEE Microwave and Wireless Components Letters in 2021.2.Current-reused VCO based on inductive-transformer feedback(ITF)technique.To further improve the performance of the oscillator and solve the balance problem of the currentreused structure,an ITF technique is proposed.In this thesis,the ITF technique is analyzed in detail,and related formulas are derived to prove the advantages of this technique: the negative resistance performance and the loaded-Q are improved,the drain-gate gain of the oscillator is enhanced,and the phase noise is reduced.It also suppresses the amplitude error of the currentreused structure.Using this technique,a current-reused VCO is designed with an operating frequency band of 6.27-8.47 GHz,an average power consumption of 7.7 m W across the whole band,and an optimal phase noise of-115.35 dBc/Hz.Relevant results were published in IEEE Transaction on Microwave Theory and Techniques in 2022.Ⅱ.Current-enhanced injection-locked frequency tripler(ILFT)The research on frequency multiplier mainly includes the following two results:1.Input signal switchable ILFT.During the initial measurement of the transceiver,it may be difficult to adjust and lock the phase-locked loop(PLL).According to the measurement requirements of the transceiver,it is proposed to add a signal selector to the input of the frequency multiplier to control whether the input of the frequency multiplier comes from the on-chip PLL or an off-chip signal source.The ILFT is designed for practical applications to increase the flexibility of transceiver measurement,and quickly measure transceiver performance without adjusting the on-chip PLL.The ILFT is based on the self-mixing injection structure,the total bandwidth reaches 32.1%,and the output frequency range is 20.04-27.69 GHz.The results were reported at the 2022 MTT-S IMWS-AMP conference.2.Dual-injection frequency tripler with auxiliary negative resistance cell.Aiming at the weak injection current of conventional ILFT,a dual-injection structure based on self-mixing is proposed.At the same time,to solve the problem of start-up difficulty caused by this technique,an additional auxiliary negative resistance cell is connected in parallel to the cross-coupling pair of the ILFT,so that the oscillator in the ILFT is easy to start-up,compared with the conventional ILFT,this technique can significantly enhance locking range and output amplitude with a small increase in power consumption.Based on this technique,an ILFT with a center frequency of 22.2 GHz was designed with an output frequency range of 17.80-26.55 GHz and an average power consumption of 8.16 m W.The achievement was published in IEEE Transaction on Microwave Theory and Techniques in 2022.Ⅲ.Current-enhanced injection-locked divider(ILFD)The research on frequency divider has achieved the following two research results.1.Divide-by-four ILFD based on a transformer-based fourth-order resonator.Aiming at the characteristic of weak injection current in the divide-by-four ILFD,a transformer-based fourth-order resonator is proposed.When the resonator is used in a frequency divider,the injection current and injection efficiency are increased,and the bandwidth of the ILFD can be effectively improved.At the same time,to improve the output spectrum purity of the ILFD,an output buffer with filtering function is adopted.Based on the above techniques,a divide-byfour ILFD operating at 27.8-31.4 GHz is designed,and the third harmonic suppression exceeds 18-dB.Related results were published in Microwave and Optical Technology Letters in 2021.2.Divide-by-three ILFD with second harmonic enhancement.Aiming at the problem of weak second harmonic at the common-mode node of the differential injectors of the divide-bythree ILFD,a second harmonic enhancement technique is proposed.The second harmonic of the common-mode node has been significantly strengthened,which increases the injection current of the divide-by-2 path in the frequency divider,and finally increases the locking range of the divide-by-three ILFD.Based on this technique,a divide-by-three ILFD in 28 GHz frequency band is designed.The locking range is 23.30-31.02 GHz,the bandwidth reaches 28.4%,and the average power consumption is 5.18 mW under 0.6 V power supply.Related results were published in IEEE Microwave and Wireless Components Letters in 2022.Ⅳ.Millimeter-wave linear dual-band radar transmitter.For the application of FMCW radar,a linear dual-band radar transmitter is designed based on the innovative structure of the frequency source.A dual-band linear tuned oscillator is proposed in the transmitter,and a transmission gate is used for bandwidth switching.The linear frequency tuning curves of the two frequency bands of 24-24.25 GHz and 24-26 GHz are realized,and the output power of the transmitter beyond 10 dBm. |
PDF Full Text Request