Solid state monolithic variable phase shifter with operation into the millimeter wave wavelength regime

Information is provided on the theory and design, fabrication, and experimental results for a phase shifter designed to operate in the millimeter wavelength region. The device was fabricated in a manner that makes it compatible with present GaAs monolithic microwave circuit technology. Continuously variable phase shift is obtained by varying the bias voltage from –5.0 to +0.65 V on a Schottky microstrip line. Experimental phase shift and loss data are provided for two different width (w) Schottky lines, w=1.5 and 7.3 m, for frequencies 2–18 GHz.     

A GaAs planar Schottky varactor diode for left-handed nonlinear transmission line applications

The left-handed nonlinear transmission line(LH-NLTL) based on monolithic microwave integrated circuit(MMIC) technology possesses significant advantages such as wide frequency band,high operating frequency,high conversion efficiency,and applications in millimeter and submillimeter wave frequency multiplier.The planar Schottky varactor diode(PSVD) is a major limitation to the performance of the LH-NLTL frequency multiplier as a nonlinear component.The design and the fabrication of the diode for such an application are presented.An accurate large-signal model of the diode is proposed.A 16 GHz-39.6 GHz LH-NLTL frequency doubler using our large-signal model is reported for the first time.The measured maximum output powers of the 2nd harmonic are up to 8 dBm at 26.4 GHz,and above 0 dBm from 16 GHz to 39.6 GHz when the input power is 20 dBm.The application of the LH-NLTL frequency doubler furthermore validates the accuracy of the large-signal model of the PSVD.     

A k-band broadband monolithic distributed frequency multiplier based on nonlinear transmission line

A fabrication technology of GaAs planar Schottky varactor diode (PSVD) is successfully developed and used to design and manufacture GaAs-based monolithic frequency multiplication based on 23-section nonlinear transmission lines (NLTLs) consisting of a coplanar waveguide transmission line and periodically distributed PSVDs. The throughout design and optimization procedure of 23-section monolithic NLTLs for frequency multiplication in the k-band range is based on a large signal equivalent model of PSVD extracted from small-signal S-parameter measurements. This paper reports that the distributed SPVD exhibits a capacitance ratio of 5.4, a normalized capacitance of 0.86 fF/μm2 and a breakdown voltage in excess of 22 V. The integrated 23-section NLTLs fed by 20-dBm input power demonstrates a 26-GHz peak second harmonic output power of 14-dBm with 25.3% conversion efficiency in the second harmonic output frequency range of 6 GHz-26 GHz.     

Broadband microwave frequency doubler based on left-handed nonlinear transmission lines

A bandwidth microwave second harmonic generator is successfully designed using composite right/left-handed nonlinear transmission lines(CRLH NLTLs) in a GaAs monolithic microwave integrated circuit(MMIC) technology. The structure parameters of CRLH NLTLs, e.g. host transmission line, rectangular spiral inductor, and nonlinear capacitor,have a great impact on the second harmonic performance enhancement in terms of second harmonic frequency, output power, and conversion efficiency. It has been experimentally demonstrated that the second harmonic frequency is determined by the anomalous dispersion of CRLH NLTLs and can be significantly improved by effectively adjusting these structure parameters. A good agreement between the measured and simulated second harmonic performances of Ka-band CRLH NLTLs frequency multipliers is successfully achieved, which further validates the design approach of frequency multipliers on CRLH NLTLs and indicates the potentials of CRLH NLTLs in terms of the generation of microwave and millimeter-wave signal source.     

Photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer

We realize a novel photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer. A near-linear phase shifter exceeding 180 degrees and a phase modulation with 2.5 Gbit/s baseband signal are obtained for a 10 GHz microwave signal by this proposed device.     

Theory study on a photonic-assisted radio frequency phase shifter with direct current voltage control

A photonic-assisted radio frequency phase shifter with direct current voltage control is proposed using a polymer- based integrated Mach-Zehnder modulator. A closed-form expression of radio frequency （RF） signal power and phase is given. Theoretical calculation reveals that by carefully setting the bias voltages, RF signal power variation lower than 1-dB and phase accuracy less than 3° can be achieved and are not degraded by perturbation of modulation index once the bias voltage drift is kept within -3% -- 3%.     

不同位置二极管串并联方式对射频电路的影响

分析了单支肖特基二极管以及串并联模拟预失真电路的幅度和相位的非线性特性,仿真结果表明可以将二极管作为模拟预失真电路可调节的核心器件。利用传输矩阵分析得出改变肖特基二极管在预失真电路的不同位置,及不同的串并联连接方式,可以使幅度相位补偿曲线得到改善。由仿真结果可以看出,在不同位置以串联或并联的形式在电路中连接二极管,可有效改变曲线的位置和斜率,从而得到理想的目标曲线形状。     

Active microwave negative-index metamaterial transmission line with gain

We studied the active metamaterial transmission line at microwave frequency. The active composite right-handed or left-handed transmission line was designed to incorporate a germanium tunnel diode with a negative differential resistance property as the gain device at the unit cell level. Measurements of the fabricated planar transmission line structures with one-, two-, and three-unit cells showed that the addition of the dc pumped tunnel diodes not only provided gain but also maintained the left handedness of the transmission line metamaterial. Simulation results agree well with experimental observation. This work demonstrated that negative index material can be obtained with a net gain when an external source is incorporated.     

铁电体移相器高功率微波应用研究

为拓展高功率微波阵列天线的波束扫描范围, 将铁电体移相器引入到高功率微波领域。分析铁电体移相器的工作原理, 并研究其应用于高功率微波领域可能遇到的问题, 利用时域有限差分法对高功率微波在铁电体材料中传播的简单模型进行分析, 研究了微波功率及偏置电场对输出波形的影响, 并进一步分析铁电体移相器应用于高功率微波领域的可行性。结果表明：在不考虑介质损耗的情形下, 选择适当的铁电体材料可以在10 cm内实现L波段180相移, 同时传输效率达到90%以上。     

铁电体移相器高功率微波应用研究

为拓展高功率微波阵列天线的波束扫描范围, 将铁电体移相器引入到高功率微波领域。分析铁电体移相器的工作原理, 并研究其应用于高功率微波领域可能遇到的问题, 利用时域有限差分法对高功率微波在铁电体材料中传播的简单模型进行分析, 研究了微波功率及偏置电场对输出波形的影响, 并进一步分析铁电体移相器应用于高功率微波领域的可行性。结果表明:在不考虑介质损耗的情形下, 选择适当的铁电体材料可以在10 cm内实现L波段180相移, 同时传输效率达到90%以上。     

Diode grids for electronic beam steering and frequency multiplication

Loading a grid with diodes offers the possibility of two-dimensional control of millimeter waves that is analogous to holography and nonlinear optics. These grids are attractive because they are suitable for monolithic integration with gallium-arsenide Schottky diodes and for high-power operation. Here we present grid designs for electronic beam-steering and harmonic generation. The beam-steering grid is a programmable reflector, where the diode bias controls the phase shift of the reflection. The variation of the phase across the grating sets the direction of the reflected beam. The reflection loss in computer simulations is 3dB at 90GHz. The harmonic-generating grid acts as a nonlinear reactive surface, where the nonlinear capacitance of the diodes produces the harmonic frequencies. Quasioptical filters select the desired harmonic. Computer simulations predict that a 65GHz-to-130GHz doubler would have an output power of 0.56W/cm² and a conversion efficiency of 35%.     

Enhanced phase sensitivity with a nonconventional interferometer and nonlinear phase shifter

We propose a theoretical scheme of an enhanced phase sensitivity by introducing a nonlinear phase shifter to the nonconventional interferometer consisting of a balanced beam splitter (BBS) and an optical parameter amplifier (OPA), a modified nonlinear interferometer (MNI). Then we use coherent state and even coherent state as inputs and homodyne detection at one output port of the MNI for phase sensitivity, both without and with photon losses. We find that the nonlinear phase shifter can not only improve phase sensitivity, but also significantly resist the decoherence from photon losses. In comparison to both the BBS+OPA scheme with linear phase shifter and the traditional Mach–Zehnder interferometer with nonlinear one, the phase sensitivity of the MNI scheme shows the best performance. It is interesting that the nonlinear phase shifter can stimulate potential of the OPA, although there is no improvement in signal-to-noise ratio beyond standard quantum limit for the BBS+OPA scheme with a linear phase shifter.     

High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 m ·cm2 with a total active area of 2.46×10-3 cm2 . Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9×10-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.     

Development of terahertz mixers and a study of their characteristics

We develop terahertz mixers with monolithic integrated circuits containing balanced, series and antiparallel pairs of Schottky diodes. The designs of these mixers and a method for studying their parameters are described. The best results are obtained for the antiparallel diode pair. In this case, the double-sideband noise temperature of the receiver amounts to 5600–7500 K when operating at the second heterodyne-oscillator harmonic near the frequency 0.71 THz.     

A quasioptical doubler-array

The design of a planar quasioptical doubler configuration with an output frequency of 290 GHz is presented. Frequency conversion is realized with a monolithic Schottky — varactor array. Coupling of electromagnetic energy from beam waveguide to chip and vice versa is carried out with integrated antenna arrays. Electromagnetic field calculations describe coupling effects between the single array elements. RF—measurements of multiplier performance are also presented.     

基于双通道马赫曾德尔调制器调制边带滤波的微波光子移相器

提出了一种基于双通道马赫曾德尔调制器(DPMZM)调制边带滤波的微波光子移相器。在双通道马赫曾德尔调制器的结构中,在一路马赫曾德尔干涉仪上实现抑制光载波的双边带调制输出,而在另一路马赫曾德尔的相位调节臂上通过调节偏置电压实现光载波信号的光学移相,两路光信号经过干涉合路后由光纤布拉格光栅(FBG)滤除其中一个一阶边带,最后输入到光电探测器(PD)进行光电转换得到移相的微波信号。实验结果表明,基于DPMZM调制边带滤波的微波光子移相器具有传输特性稳定、输出幅度波动小的优点。该结构还具有相移调节响应速度快、应用频带宽以及移相范围大于360°等特点。     

AN UNCOOLED VERY LOW NOISE SCHOTTKY DIODE RECEIVER FRONT-END FOR MIDDLE ATMOSPHERIC OZONE AND CARBON MONOXIDE MEASUREMENTS

The paper describes an uncooled front-end of the Schottky diode receiver system, which may be applied for observations of middle atmospheric ozone and carbon monoxide thermal emission lines at frequencies 110.8 GHz and 115.3 GHz, respectively. The mixer of the front-end has utilized high-quality Schottky diodes that allowed us to reduce the mixer conversion loss. The combination of the mixer and an ultra-low-noise IF amplifier in the one integrated unit has resulted in double-sideband (DSB) receiver noise temperature of 260 K at a local oscillator (LO) frequency of 113.05 GHz in the instantaneous IF band from 1.7 to 2.7 GHz. This is the lowest noise temperature ever reported for an uncooled ozone receiver system with Schottky diode mixers.     

Monolithic integration of an AlGaN/GaN metalinsulator field-effect transistor with an ultra-low voltage-drop diode for self-protection

In this paper,we present a monolithic integration of a self-protected AlGaN/GaN metal-insulator field-effect transistor(MISFET).An integrated field-controlled diode on the drain side of the AlGaN/GaN MISFET features a selfprotected function for a reverse bias.This diode takes advantage of the recessed-barrier enhancement-mode technique to realize an ultra-low voltage drop and a low turn-ON voltage.In the smart monolithic integration,this integrated diode can block a reverse bias(> 70 V/μm) and suppress the leakage current(< 5 × 10-11 A/mm).Compared with conventional monolithic integration,the numerical results show that the MISFET integrated with a field-controlled diode leads to a good performance for smart power integration.And the power loss is lower than 50% in conduction without forward current degeneration.     

Monolithic integration of AlGaN/GaN metal—insulator field-effect transistor with ultra-low voltage-drop diode for self-protection

In this paper, we present a monolithic integration of self-protected AlGaN/GaN metal-insulator field-effect transistor (MISFET). An integrated field-controlled diode on the drain side of the AlGaN/GaN MISFET features self-protected function at reverse bias. This diode takes advantage of the recessed-barrier enhancement-mode technique to realize an ultra-low voltage drop and a low turn-ON voltage. In the smart monolithic integration, this integrated diode can block reverse bias (>70 V/μm) and suppress the leakage current (<5×10^-11 A/mm). Compared with conventional monolithic integration, the numerical results show that the MISFET integrated with a field-controlled diode leads to a good performance for smart power integration. And the power loss is lower than 50% in conduction without forward current degeneration.     

Nonlinear microwave phase shifter on electromagnetic-spin waves

Nonlinear microwave phase shifter based on a multiferroic structure consisting of layers of iron-yttrium garnet and barium—strontium titanate is studied experimentally. The structure is a waveguide for nonlinear electromagnetic-spin waves. The triple control over phase shift of electromagnetic-spin waves (namely, by varying the power of the input microwave signal, the magnetic bias field of the structure, and electric displacement field) is demonstrated.