Research On CMOS Mm Wave Oscillator And Its Applications

With the advancement of CMOS technology,LC oscillators and distributed oscillators have been widely used in various wireless communication transceiver systems due to their low noise,low jitter,low skew and multi-phase.However,due to the extremely low quality factor of var-actors and non-negligible transistor noise in the mm-wave bands,phase noise and tuning range are the main reasons restricting the further development of traditional oscillator.At the same time,the performance of passive devices in mm-wave integrated circuits is heavily dependent on the thickness of the metal layer,and digital processes tend to use thinner metals to reduce the restriction for line width and spacing.It still faces the challenge of full integration with large-scale digital logic circuits.Therefore,this paper mainly adopts standard CMOS process to overcome the loss caused by the thin metal on the top layer,to optimize passive devices and circuit topologies,and to achieve desirable performances.Facing these challenges and meet-ing the needs of different scenarios,this paper studies LC oscillators and distributed oscillators from three dimensions:basic theory,circuit structure improvement and system application.In this paper,three clock generation circuits,a wide-tuning-range VCO with a tunable harmonic-resonant transformer,a standing wave oscillator based on digital-controlled artificial dielectric differential transmission lines,and a multi-phase rotating traveling wave oscillator,are imple-mented and applied to mm-wave transmitters and circulators.The main work and innovations of the paper are as follows:For low phase noise and wide tuning range,this paper presents a wide-tuning-range VCO with a tunable harmonic-resonant transformer.By using a 1:1 stacked transformer,the capac-itance ratio of the capacitor arrays on both sides of the primary coil and the secondary coil during the tuning process is fixed,so that the three resonance peaks generated by the resonator in differential mode and common mode are always located atω₀,2ω₀and 3ω₀,the effectiveness of class-F_2,3oscillators with low phase noise is maintained over the entire tuning range.The proposed oscillator is fabricated in a standard 55 nm CMOS process.The measurements show a phase noise of-108.62 d Bc/Hz at 1 MHz offset,a tuning range of 22%,and a center frequency of 14.52 GHz.The core power consumption of the oscillator is 15 m W,indicating that Fo M and Fo M_Tare-180.10 d Bc/Hz and-186.80 d Bc/Hz,respectively.Aiming at the limited tuning capability of capacitor arrays in traditional standing wave oscillators,this paper proposes a standing wave oscillator based on digital-controlled artificial dielectric differential transmission lines.Using the digital controlled artificial dielectric trans-mission line,the tuning range is expanded without occupying additional area.The structural advantage of the differential transmission line in the standing wave oscillator is effectively uti-lized,and the distributed features of the standing wave oscillator is kept.Measurement results show a tuning range of 19.2 GHz to 21.6 GHz with a sub-band of 300 MHz.The phase noise is-104.7 d Bc/Hz,offset by 1 MHz,corresponding to a frequency of 19.47 GHz.The power dissipation of the oscillator including the buffer is 7.5 m W,and the Fo M and Fo M_Tare-181.8d Bc/Hz and-183.3 d Bc/Hz,respectively.At the same time,a rotating traveling wave oscillator is designed for the needs of multi-phase clocks and is implemented in standard 55 nm CMOS process.The quadrature signals have operating frequencies of 26.8-28.7 GHz,the phase error is less than 4.7?,and the phase noise at 1 MHz offset can reach-95 d Bc/Hz.The application of oscillators in transmitter and full-duplex circulator is also investigated.The proposed wide-tuning-range VCO with a tunable harmonic-resonant transformer,frequency multiplier,driver amplifier and modulator constitutes a Ka-band transmitter system with-10d Bm output power and OOK modulation function.In addition,in the process of exploring the circulator,the time-varying transmission line with carrier enhancement technology is proposed for reducing the loss of traditional time-varying transmission lines at high frequencies.By increasing the carrier amplitude,the frequency conversion gain can be increased by up to 10 d B,thereby lowering the noise of the RF front-end circuit.In addition,in view of the disadvantage of low modulation index,the spatiotemporal conductivity modulation circulator is mainly studied.A fully integrated non-magnetic passive circulator is realized by using a rotating traveling-wave oscillator that generates an on-chip quadrature signal.The circulator operates in the 9 GHz band,and the insertion loss from ANT to RX and TX to ANT is as low as 3.9 d B and 2.5 d B,respectively,and the TX to RX isolation is 13.4–18.1 d B.