Group delay equalised monolithic microwave integrated circuit amplifier for ultra-wideband based on right/left-handed transmission line design approach

A group delay equalised InGaP/GaAs HBT monolithic microwave integrated circuit (MMIC) amplifier with an active balun for ultra-wideband (UWB) application has been developed. The MMIC consists of a broadband amplifier with an active balun and a group delay equaliser. The group delay equaliser was designed based on a theory using a composite right/left-handed (CRLH) transmission line. Adding a right-handed (RH) transmission line to a CRLH transmission line in parallel, a convex group delay characteristic is realised. Since various UWB components have concave group delay characteristics, the group delay equaliser can compensate a concave group delay characteristic of the amplifier in an operation frequency band. In this paper, dispersion, group delay and impedance characteristics for the proposed CRLH/RH circuit have been theoretically analysed. Moreover, a minimised group delay equaliser circuit on an MMIC has been designed and fabricated based on the proposed CRLH/RH circuit. A fabricated group delay equalised InGaP/GaAs HBT MMIC amplifier with an active balun exhibited an improved group delay characteristic compared with the MMIC amplifier without the group delay equaliser. The standard deviations of group delays for a frequency variation in a gain band were decreased from 12.8 to 5.5 ps at S₂₁ and decreased from 10.3 to 7.3 ps at S₃₁.     

A microwave photonic generator of chaotic and noise signals

The transition to chaos in a microwave photonic generator has been experimentally studied for the first time, and the generated broadband chaotic microwave signal has been analyzed. The generator represented a ring circuit with the microwave tract containing a low-pass filter and a microwave amplifier. The optical tract comprised a fiber delay line. The possibility of generating chaotic oscillations with uniform spectral power density in a 3–8 GHz range is demonstrated.     

Prototype of a microwave generator with a high-temperature superconductor disk resonator in a feedback circuit with a low phase-noise level

Phase noise of a prototype of microwave generator with a disk resonator based on high-temperature superconductor (HTSC) Y₁Ba₂Cu₃O_{7 ? δ} films in the feedback circuit has been measured for the first time. The disk resonator was cooled to a temperature of 77 K, while the other generator components remained at room temperature. The generator carrier frequency was 7.5 GHz. Phase noises have been measured for different offsets from the carrier frequency. For example, the minimum measured phase-noise level was found to be 136.2 dB/Hz for a 10-kHz offset from the carrier frequency. It is shown that the results obtained correspond to the classical Leeson formula with flicker noise neglected. Thus, a disk resonator based on Y₁Ba₂Cu₃O_{7 ? δ} films does not introduce additional noise (in comparison with the amplifier noise) at small offsets and, correspondingly, is promising for microwave generators with extremely low phase noise. The possibility of further decrease in the phase-noise level by increasing the Q factor of the HTSC disk resonator and optimizing its housing design is discussed.     

Chaotic millimeter-wave generation on the basis of wideband gyro-amplifiers with a helical corrugated waveguide

The possibility of generating random noiselike radiation in gyro-amplifiers with a helical corrugated waveguide when introducing delayed feedback has been shown. The cyclotron resonance detuning corresponding to the maximum slope of the amplitude characteristic of an amplifier after saturation is optimal for implementing the mode of developed dynamic chaos. Assessments are carried out for the parameters of a noise generator based on an experimentally implemented gyro-travelling-wave tube of 35-GHz band, according to which the generation of multifrequency radiation is possible with a spectrum width of 3—4 GHz, an average power up to 70 kW, and an efficiency of order of 10%.     

A microwave cryogenic low-noise amplifier based on sige heterostructures

A low-noise cryogenic amplifier for the measurement of weak microwave signals at sub-Kelvin temperatures is constructed. The amplifier has five stages based on SiGe bipolar heterostructure transistors and has a gain factor of 35 dB in the frequency band from 100 MHz to 4 GHz at an operating temperature of 800 mK. The parameters of a superconducting quantum bit measured with this amplifier in the ultralow-power mode are presented as an application example. The amplitude–frequency response of the “supercon-ducting qubit–coplanar cavity” structure is demonstrated. The ground state of the qubit is characterized in the quasi-dispersive measurement mode.     

1V脉冲驱动型交流量子电压源研究

脉冲驱动型交流量子电压标准ACJVS通过高速脉冲序列驱动约瑟夫森结阵芯片的方式实现宽频带交流量子电压的合成,相比于可编程型交流量子电压标准PJVS,具有免台阶切换、频谱纯净、频带宽等优点。搭建的系统主要包括8位高速脉冲码型发生器、微波放大器、直流阻断、约瑟夫森结阵芯片等。通过驱动包含4个子阵列,每个子阵列含12810个约瑟夫森结的结阵芯片,并结合4通道联合低频补偿的方式,成功产生了1V有效值的脉冲驱动型交流量子电压,为进一步建立交流量子电压基准打下了坚实的基础。最后,展望了脉冲驱动型交流量子电压在量子阻抗桥、交流量子功率源、交流量子功率表方面的应用价值。     

Highly efficient <Emphasis Type="Italic">X</Emphasis>-range AlGaN/GaN power amplifier

The development of microwave power amplifiers (PAs) based on transistors with an AlGaN/GaN heterojunction are discussed in terms of the possible enhancement of their efficiency. The main focus is on the synthesis of the transforming circuits, which ensure the reactive load at the second- and third-harmonic frequencies and complex impedance at the fundamental frequency. This makes it possible to optimize the complex operation mode of a PA; i.e., to reduce the scattering power and enhance the efficiency. A microwave PA based on the Schottky-barrier-gate field-effect transistor with 80 electrodes based on the GaN pHEMT transistor with a gate length of 0.25 nm and a gate width of 125 nm is experimentally investigated. The amplifier has a pulse output power of 35 W and a power-added efficiency of at least 50% at a working frequency of 9 GHz.     

Hyperbolic chaos generator based on coupled drift klystrons

A scheme of the generator of chaotic oscillations in the microwave band is proposed that is based on two drift klystrons coupled in a ring circuit. The first klystron doubles the frequency of the input signal and the second klystron mixes the second harmonic signal and the reference signal representing a periodic sequence of radio pulses filled with the third harmonic, followed by separation of the differential first harmonic signal. As a result, the transformation of the signal phase during the period of pulse repetition is described by a stretching map of the circle (Bernoulli map) and demonstrates chaotic behavior. Results of numerical calculations are presented that confirm the implementation of the proposed mechanism to ensure the generation of robust, structurally stable chaos in the system under consideration.     

Tunable inversionless laser for the far-infrared and terahertz range based on nanoheterostructures with quantum wells

A new variant of the active medium capable of ensuring tunable inversionless generation and/or amplification of electromagnetic radiation in the far-IR and terahertz range is proposed and characterized. The medium is based on a comparatively simple semiconductor nanoheterostructure with quantum wells, which is capable of operating in a pulsed regime at room temperature. A severalfold change in the working frequency of the amplifier/generator can be achieved by varying the pumping radiation intensity. The proposed amplifier/generator (laser) can serve as a convenient, cheap and compact tunable source of far-IR and terahertz radiation for various technical and medical applications.     

An ultrawide-band microwave radar sensor for nondestructive evaluation of pavement subsurface

A new ultrawide-band (UWB) microwave radar sensor operating from 0.6 to 5.6 GHz has been developed using microwave integrated circuits for pavement subsurface characterization. UWB antennas operating from 0.5-10-GHz have been designed and tested for use in the sensor. A new simple, yet effective, accurate procedure was also developed to compensate for the common amplitude deviations and nonlinear phase errors produced by the inherent imperfection of the system. The developed compensation method is applicable to other systems and effectively reduces the potential masking of adjacent targets as well as facilitating and increasing the accuracy for target identification of the sensor. The sensor has been used to assess a pavement sample with less than 0.1 in of error in the pavement's layer thickness. The developed system represents the first UWB stepped-frequency radar sensor completely realized using microwave integrated circuits over the frequency range of 0.6-5.6 GHz for subsurface sensing applications.     

Exploring figures of merit associated with the suboptimum operation of class-E power amplifiers

Closed-form design equations for the operation of a class-E amplifier for zero switch voltage slope and arbitrary duty cycle are derived. This approach allows an additional degree of freedom in the design of class-E amplifiers which are normally designed for 50% duty ratio. The analysis developed permits the selection of non-unique solutions where amplifier efficiency is theoretically 100% but power output capability is less than that the 50% duty ratio case would permit. To facilitate comparison between 50% (optimal) and non-50% (suboptimal) duty ratio cases, each important amplifier parameter is normalised to its corresponding optimum operation value. It is shown that by choosing a non-50% suboptimal solution, the operating frequency of a class-E amplifier can be extended. In addition, it is shown that by operating the amplifier in the suboptimal regime, other amplifier parameters, for example, transistor output capacitance or peak switch voltage, can be included along with the standard specification criteria of output power, DC supply voltage and operating frequency as additional input design specifications. Suboptimum class-E operation may have potential advantages for monolithic microwave integrated circuit realisation as lower inductance values (lower series resistance, higher self-resonance frequency, less area) may be required when compared with the results obtained for optimal class-E amplifier synthesis. The theoretical analysis conducted here was verified by harmonic balance simulation, with excellent agreement between both methods.     

24-GHz ultra-wideband transmitter for vehicular short-range radar applications

This paper presents a 24-GHz transmitter for ultra-wideband short-range radar applications fabricated in a 0.13-μm SiGe:C BiCMOS technology. The circuit is composed of a frequency synthesiser, based on 24-GHz voltage-controlled oscillator in an N-integer phase-locked loop (PLL), a RF switch delivering a 0-dBm output power, and a tunable rectangular pulse generator, whose pulse width covers a range between 0.5 and 1.2 ns. The transmitter has been developed for a flip-chip bumping assembly on a module with an UWB antenna. Assuming a 10.5-dBi antenna gain, it is compliant with European Telecommunications Standards Institute (ETSI) transmission mask and is able to cover the main automotive applications addressing both a resolution better than 0.1 m and maximum unambiguous range of 15 m.     

A Microwave Transmission Instrument for Rapid Dry Rubber Content Determination in Natural Rubber Latex

We report the design, implementation and testing of an instrument for rapid dry rubber content (DRC) determination in rubber latex. It is composed of rectangular waveguide antennae, microwave generator, power detector, and microcontroller. According to the theory of microwave transmission, the power loss of microwaves passing through latex is related to the DRC. This attenuation is determined by measuring the transmitted microwave intensity with a power detector. The appropriate frequency that gives the best correlation between DRC and attenuation was found to be about 2.36 GHz. The microwave power measurement is processed by the microcontroller using the empirical calibration equation to estimate DRC in rubber latex. The instrument was tested using new latex samples with various DRC, sampled locally in Songkhla province, Thailand, and the DRC estimates by the instrument were compared to the slow but accurate standard oven-drying results. The estimates had an 0.21 % mean error and R ² = 0.9983, indicating good practical performance.     

Oxygen atom density in microwave oxygen plasma

We determined the density of neutral oxygen atoms in microwave plasma using a fiber-optics catalytic probe (FOCP). Plasma was created within a quartz tube with an outer diameter of 5 cm by a 2.45 GHz microwave generator with an output power up to 1000 W. The oxygen flow was varied between 4 and 20 l/h. The O-atom density was found to increase monotonically with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the oxygen flow of 4 l/h, it was about 18% but it decreased to about 6% at the flow of 20 l/h.     

Super Compact UWB Monopole Antenna for Small IoT Devices

This article introduces a novel, ultrawideband (UWB) planar monopole antenna printed on Roger RT/5880 substrate in a compact size for small Internet of Things (IoT) applications. The total electrical dimensions of the proposed compact UWB antenna are 0.19 λ_o × 0.215 λ_o × 0.0196 λ_o with the overall physical sizes of 15 mm × 17 mm × 1.548 mm at the lower resonance frequency of 3.8 GHz. The planar monopole antenna is fed through the linearly tapered microstrip line on a partially structured ground plane to achieve optimum impedance matching for UWB operation. The proposed compact UWB antenna has an operation bandwidth of 9.53 GHz from 3.026 GHz up to 12.556 GHz at −10 dB return loss with a fractional bandwidth (FBW) of about 122%. The numerically computed and experimentally measured results agree well in between. A detailed time-domain analysis is additionally accomplished to verify the radiation efficiency of the proposed antenna design for the ultra-wideband signal propagation. The fabricated prototype of a compact UWB antenna exhibits an omnidirectional radiation pattern with the low peak measured gain required of 2.55 dBi at 10 GHz and promising radiation efficiency of 90%. The proposed compact planar antenna has technical potential to be utilized in UWB and IoT applications.     

Microwave power amplifiers based on AlGaN/GaN transistors with a two-dimensional electron gas

A technique for synthesis of microwave power amplifiers based on transistors with a AlGaN/GaN heterojunction is discussed. Special focus is on the development of a technique for synthesis of transformation circuits of the power amplifier to increase efficiency with a retained high output power. The use of independent matching at the harmonic frequencies and fundamental frequency makes it possible to control the attainable efficiency in a wide frequency band along with the total suppression of harmonics beyond the operational band. Microwave power amplifiers for operation at 4 and 9 GHz have been developed and experimentally investigated.     

A widely linear temperature to frequency converter using athermistor in a pulse generator

A modification of an existing technique for thermistor linearization is presented. A temperature-measuring circuit using a thermistor in a specially designed pulse generator is used to obtain a highly linear relation between absolute temperature and frequency. The use of a general-purpose operational amplifier and two switching transistors in the design of the pulse generator provides a temperature scale that is linear over a wide range of values on a high degree of sensitivity. The result shows that an extremely high degree of linearity is achieved by this method     

Ultra-wide bandwidth in-vehicle channel measurements using chirp pulse sounding signal

A novel ultra-wide bandwidth (UWB) channel measurement approach based on chirp pulse sounding signal in an automotive vehicle is proposed. An UWB channel impulse response (CIR) estimator using de-convolution technique is constructed to verify that the chirp pulse sounding signal generated with rectangular window is 12.71 dB better in accuracy than the Gaussian pulse sounding signal to measure the CIR of the UWB channel. The UWB channel measurement in the frequency band of 4.25-4.75 GHz is carried out inside an automotive vehicle. The experimental results validate the correctness of using chirp pulse sounding signal to measure the UWB channel inside an automotive vehicle with windows closed through the root mean square delay spread for Cases A and B radio propagation channel models of IEEE 802.15.3a UWB standard when the threshold is properly chosen. Also, test results show that opening the vehicle s window may change the channel characterisation.     

An S-band vircator with premodulated electron beam based on a compact generator with inductive energy storage

An experimental S-band vircator with premodulated electron beam based on a compact generator with inductive energy storage is described. The vircator radiation power was 300 MW at a power efficiency of about 5% and a pulse duration of 50 ns. The oscillation frequency, determined by the electrodynamic system parameters, remained unchanged during the pulse.     

动态磁性能测试仪的研究

研制出频率范围 5 0Hz～ 5 0kHz的动态磁性能测量仪样机 ,该仪器是基于 16位微处理器的便携式仪器 ,包含信号源、功率放大器、电压表、电流表和功率表。采用准同步采样方法和数值积分算法 ,计算磁滞回线和损耗、磁导率等参数。