The development of nonradiative dielectric waveguide transmitting front-end in Ka-band

The operating theory,design method and experimental results of the nonradiative dielectric waveguide (NRD-guide) transmitting front-end in millimeter wave band are related in details in this paper. As a kind of dielectric waveguide,the NRD-guide possesses fine transmission performances, and it can be used to fabricate the millimeter wave hyterodyne integrated circuits. The two kinds NRD-guide transmitting front-ends substantiated in the paper, the voltage controlling oscillator(VCO) and twin-Gunn-diode power-combiner,have very similar structures to each other and possess compact sizes, fine machinery and electric performances.For the VCO front-end in Ka-band, the frequency modulation band is greater than 150MHz, the output power is larger than 20mW.For the power-combiner, the output power is larger than 40mW,the combination efficiency is better than 90%,the frequency stabilization reaches 1.68×10^–5. Combined with the receiving front-end reported before,the transmitter and receiver can be composed to a dielectric waveguide R/T module to be applied in some millimeter wave sub-systems.     

Varactor-tuned gunn diode voltage controlled oscillator antenna array

A simple varactor tuned X-band Gunn diode VCO antenna array which is strongly coupled has been demonstrated. These arrays have the advantages of simple biasing circuit, no resistors required to eliminate multimode problem and suitable for monolithic integration circuit. Preliminary results show a maximum tuning range of 47MHz for 1×1 array and 170MHz for 2×2 array. In order to solve power combining heating problem, we move the backside metal forward and it becomes a microstrip form. The measured frequency and radiation patterns of these grid arrays agree very well with theoretical calculations.     

A monolithic 180 nm CMOS dosimeter for In Vivo Dosimetry medical application

The design and development of a monolithic system-on-chip dosimeter fabricated in a standard 180 nm CMOS technology is described. The device is intended for real time In Vivo measurement of dose of radiation during radiotherapy sessions. Owing to its proposed small size, of approximately 1 mm³, such solution could be made in-body implantable and, as such, provide a much-enhanced high-resolution, real-time dose measurement for quality assurance in radiation therapy. The device transmits the related information on dose of radiation wirelessly to an external receiver operating in the MICS band. The various phases of this two years project, started in 2011, including the design and development of radiation sensors and integrated RF to perform the readout, will be described.     

A Gunn-Diode Active Leaky-Wave Frequency Scanning Antenna

A frequency tunable active leaky-wave scanning antenna using Gunn-diode voltage control oscillator (VCO) as source is developed. The frequency tuning controlled by changing either the varactor diode dc bias or the Gunn diode dc bias is demonstrated. The measured scanning angle of active antenna is close to 15 degree as the Gunn VCO frequency tuned from 12.58GHz to 12.98GHz. To excite the first higher order mode of the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the middle line of the microstrip leaky wave antenna. This is a prototype of frequency scanning antenna using two terminal device, which can be easily scaled up to millimeter wave frequency region.     

The digital predistortion of non-linear frequency modulation of voltage-controlling-oscillator in MM-band

The reason and rectification method of the non-linear frequency modulation of voltage-controlling-oscillator in millimeter-wave band have been presented in this paper. The digital predistortion for the controlling signal of the varactor in VCO possesses high rectification sensitivity, simple circuit and convenient adjustment. The method can be used in mm-wave and microwave VCOs that are fabricated by all kinds' transmission lines, and can eliminate the dispersion of FM characteristic in VCOs that are usually caused by the machining deviation and the inconsistent parameters of semiconductors. The digital predistortion technique has been applied in NRD-guide VCO in Ka-band, which main performances are: f0 = 36.30648GHz, the frequency-stability reaches 2.26×10^–5, the maximum frequency-deviation is 150MHz, the linear-FM error is less than 5%.     

An asymmetric feeding X-band active frequency-scanning leaky-wave antenna

An asymmetric feeding X-band active leaky-wave antennas is developed, to excite the first high order mode of the microstrip leaky wave antenna. One is the asymmetric feeding leaky-wave antenna which integrated with a HEMT oscillator, and the other is the frequency-tuned leaky-wave antenna which integrated with a varactortuned HEMT VCO. The microstrip leaky-wave antenna is operated in the first higher mode. To excite the first higher mode, the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the center of the microstrip leaky wave antenna. The design of these active leaky-wave antennas is discussed and the beam scanning phenomena of the antenna is presented. The HEMT oscillator frequency is controlled by tuning the varactor DC bias and the beam scanning is demonstrated. The measured scanning angle agree with prediction, it is close to 30° as the VCO frequency tuned from 8.06 GHz to 9GHz.     

利用负载电流产生微波的新型MILO

 为了进一步提高MILO产生微波的功率和效率，提出了其负载电流能量全部利用来产生微波的新思想。设计并运用二维全电磁PIC方法模拟了基于此思想的新型MILO，它是传统MILO与VCO的有机结合(简称MVO)。模拟结果表明MVO中MILO部分与作为MILO负载的VCO部分各自工作正常，VCO部分产生微波的主频受MILO部分产生微波的牵引。在输入25GW电功率（工作电压约500kV）下，与相应传统MILO相比，MVO的微波平均输出功率提高了500MW，效率从6%提高到了8%。     

Nonlinear Frequency-Modulation Distortion Analysis for VCO Based on Harmonic Balance Method

The analysis methods for the steady-state responses of the voltage tuning negative resistance oscillator (voltage-controlling oscillator, VCO) by the microwave nonlinear autonomous circuit harmonic balance method in millimeter-wave bands are studied in the paper. Firstly, the quasi-periodic characteristic of the steady-state response of the VCO modulated by a periodic signal is proved. Then, on the bases of the harmonic balance analysis and the inter-modulation balance analysis, a novel method for obtaining the steady-state tuning performance and the nonlinear frequency-modulation distortion characteristic of the VCO is presented. The total analysis process is aimed to a kind of NRD-guide Gunn diode VCO. The large-signal lumped equivalent circuit model of the millimeter-wave P⁺N-junction varactor is also given for explaining the algorithm and the principle of the NRD-guide VCO.     

Chip design of a 5.8-GHz fractional-N frequency synthesizer with a tunable Gm—C loop filter

This paper proposes a novel Gm-C loop filter instead of a conventional passive loop filter used in a phase-locked loop.The innovative advantage of the proposed architecture is tunable loop filter bandwidth and hence the process variations of passive elements of resistance R and capacitance C can be overcome and the chip area is greatly reduced.Furthermore,the MASH 1-1-1 sigma-delta(Σ▽) modulator is adopted for performing the fractional division number and hence improves the phase noise as well.Measured results show that the locked phase noise is 114.1 dBc/Hz with lower G m-C bandwidth and 111.7 dBm/C with higher G m-C bandwidth at 1 MHz offset from carrier of 5.68 GHz.Including pads and built-in Gm-C filter,the chip area of the proposed frequency synthesizer is 1.06 mm 2.The output power is 8.69 dBm at 5.68 GHz and consumes 56 mW with an off-chip buffer from 1.8-V supply voltage.