Low-loss and high-selectivity bandpass filter with harmonic suppression and piezoelectric transducer tuning

A low-loss and high-selectivity bandpass filter with harmonic suppression and piezoelectric transducer (PET) tuning is presented. At the 3.5 GHz passband, the insertion loss is 1.48 dB, and the transmission zeros at 3.05 and 4.08 GHz have a rejection of 55 dB. The rejection at the 7 GHz second harmonic is 50 dB. A PET tunes the bandstop sections to obtain a tunable suppression (>45 dB) around the second harmonic from 5.35 to 7.8 GHz.     

High efficiency and output power from second- and third-harmonicmillimeter-wave InP-TED oscillators at frequencies above 170 GHz

InP TED (transferred electron device) oscillators have been experimentally investigated for frequencies between 170 and 279 GHz. It has been found that output powers of more than 7 and 0.2 mW are possible at 180 and 272 GHz using second- and third-harmonic mode operation, respectively. Conversion efficiencies of more than 13% and 0.3% between fundamental and second harmonic and fundamental and third harmonic, respectively, have been found. The conversion efficiencies are comparable to GaAs TEDs. The output powers, conversion efficiencies, and tuning ranges (more than 22%) are the biggest reported for InP TEDs at these frequencies. The output power at third harmonic was sufficient for supplying a superconducting mixer with local oscillator power     

Coplanar Waveguide Bandpass Filters With Compact Size and Wide Spurious-Free Stopband Using Electromagnetic Bandgap Resonators

This work presents a novel coplanar waveguide (CPW) bandpass filter (BPF) that uses electromagnetic bandgap (EBG) resonators to reduce the size and suppress the harmonic responses. The propagation characteristic of the EBG structure is investigated by its associated equivalent circuit model. Compared with the conventional half-wavelength resonator at 5GHz, the EBG resonator is 60.5 % more compact. Based on the EBG CPW resonators, the inductively-coupled two-pole BPF with 3.8% 3-dB bandwidth and 2-dB insertion loss at 5GHz is implemented. This structure generates a 59.6% reduction in size and suppresses a second harmonic passband when compared with a conventional filter. To eliminate the third harmonic response, the proposed EBG CPW BPF further incorporates two EBG structures into its input and output ports and has the merit of a small circuit area     

Millimeter- and submillimeter-wave multipliers usingquantum-barrier-varactor (QBV) diodes

Experimental results are presented using quantum-barrier-varactor (QBV) diodes in harmonic multipliers. Output powers and tripler conversion efficiencies of more than 2 mW and 5%, respectively, were achieved between 210 and 280 GHz. In a crude experiment, an efficiency of more than 0.2% for the fifth harmonic was measured at 310 GHz. The values for the QBV diode as a tripler are comparable to state-of-the-art results for Schottky-varactor diode triplers. The experimental results agree well with theoretical calculations     

Generation of Submillimeter-Wave Radiation with GaAs Tunnett Diodes and InP Gunn Devices in a Second or Higher Harmonic Mode

Efficient second-harmonic power extraction was demonstrated recently with GaAs tunnel injection transit-time (TUNNETT) diodes up to 235 GHz and with InP Gunn devices up to 325 GHz. This paper discusses the latest theoretical and experimental results from second-harmonic power extraction at submillimeter-wave frequencies and explores the potential of using power extraction at higher harmonic frequencies to generate continuous-wave radiation with significant power levels at frequencies above 325 GHz. Initial experimental results include output power levels of more than 50 μW at 356 GHz from a GaAs TUNNETT diode in a third-harmonic mode and at least 0.2–5 μW in the frequency range 400–560 GHz from InP Gunn devices in a third or higher harmonic mode. The spectral output of these submillimeter-wave sources was analyzed with a simple Fourier-transform terahertz spectrometer and, up to 426 GHz, with a spectrum analyzer and appropriate harmonic mixers. Initial experimental results from a GaAs/AlAs superlattice electronic device at D-band (110–170 GHz) and J-band (170–325 GHz) frequencies are also included.     

Ultrahigh-efficiency power amplifier for space radar applications

This paper describes a broad-band switch mode power amplifier based on the indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. The amplifier combines the alternative Class-E mode of operation with a harmonic termination technique that minimizes the insertion loss of matching circuitry to obtain ultrahigh-efficiency operation at X-band. For broad-band Class-E performance, the amplifiers output network employs a transmission line topology to achieve broad-band harmonic terminations while providing the optimal fundamental impedance to shape the output current and voltage waveforms of the device for maximum efficiency performance. As a result, 65% power-added efficiency (PAE) was achieved at 10 GHz. Over the frequency band of 9-11 GHz, the power amplifier achieved 49%-65% PAE, 18-22 dBm of output power, and 8-11 dB gain at 4 V supply. The reported power amplifier achieved what is believed to be the best PAE performance at 10 GHz and the widest bandwidth for a switch-mode design at X-band.     

Harmonic emission from high-power high-frequency gyrotrons

The results of a study of second-harmonic emission from a gyrotron designed for high-power high-frequency operation at the fundamental of the cyclotron frequency are presented. Stable, very narrow bandwidth second-harmonic cavity emission from 209 GHz to 302 GHz has been observed. An output power of 25 kW and efficiency of 6·5% in the TE_{11, 2, 1}, mode at 241 GHz is reported; this represents the highest power obtained to date from a high-frequency (> 100 GHz) harmonic gyrotron. These experiments have been carried out in a cavity for which the mode density is very high; the cavity diameter is approximately six free-space wavelengths for emission at the second harmonic. Mode competition between fundamental and second-harmonic modes is discussed. It is also shown that, in general, gyrotrons designed for high-power low-Q operation in overmoded cavities at the fundamental will also have high efficiencies and strong emission in second-harmonic modes. Prospects for high-frequency harmonic gyrotrons for plasma diagnostics and other applications are described     

A Broadband CMOS Frequency Tripler Using a Third-Harmonic Enhanced Technique

A third harmonic enhanced technique is proposed to implement a broadband and low-phase-noise CMOS frequency tripler. It nonlinearly combines a pair of differential fundamental signals to generate deep cuts at the peaks of the fundamental waveform, resulting in a strong third harmonic frequency output. This mechanism has inherent suppression on the fundamental and the other harmonics so that only a low-Q high-pass filter on the lossy silicon substrate is applied at the output to further reject the fundamental and the second harmonic frequencies, in contrast to the high-Q filters used in most of the previous tripler designs. The fabricated circuit using 0.18 m CMOS technology is compact and has an input frequency range from 1.7 GHz to 2.25 GHz, or an output frequency range from 5.1 GHz to 6.75 GHz, resulting in about 28% frequency bandwidth. The optimum conversion loss from the tripler is 5.6 dB (27.5% efficiency) at an input power of 2 dBm. The suppressions for the fundamental, second and fourth harmonics in the measurement are better than 11 dB, 9 dB, and 20 dB within an input power range from 2 dBm to 7 dBm.     

应用于S频段的宽带高谐波抑制的F类功率放大器的设计

采用InGaP/GaAs HBT工艺设计了一个适用于S频段的宽带F类功率放大器,管芯大小为3×3×0.82mm3。为了同时实现高谐波抑制和宽带,在宽带匹配电路中使用了谐波陷波器。在1.8~2.5 GHz范围内,该匹配网络的输入阻抗约为一个常电阻,二次谐波阻抗约为零而三次谐波阻抗接近无穷大,因此提高了功率放大器的效率。输入测试信号为连续波,测试结果表明该功率放大器在1dB压缩点下的输出功率约为34dBm,PAE约为57%,2到4次谐波分量功率均小于-53dBc。     

A packaged Schottky diode as detector,harmonic mixer,and harmonic generator in the 25–500 GHz range

This paper describes experimental results obtained with a packaged GaAs Schottky barrier diode in contact with a coaxial connector and placed across waveguides for bands Ka, V, E, W or F. Among the microwave sources used for calibration were 9 carcinotrons in the frequency interval 51–490 GHz. As soon as the frequency F is above the waveguide cut-off frequency, the different characteristics do not depend critically on the waveguide size for V, E, W and F bands. The video detection sensitivity, of several 100 mV/mW at 50 GHz and below, decreases as F^?4 in the range 51–500 GHz. Coupling an X-band centimeter frequency via the coaxial connector and a millimeter frequency via the waveguide permits harmonic mixing in the diode. Between 36 and 490 GHz, the harmonic mixing number varies from 3 up to the very large value 40 with conversion losses from 18 to 88 dB. The minimum detectable signal in the 100 kHz band can be as low as ?90 dBm at 80 GHz. A noticeable millimeter power is available at the waveguide output from injected centimeter power by harmonic generation. Starting for instance with 100 mW around 11.5 GHz, we have measured 0.1 mW at 80 GHz and 0.1 μW at 230 GHz. To illustrate the possibility of creating usable millimeter and submillimeter wave without heavy equipment (such as carcinotrons or millimeter klystron) we report spectroscopic experiments in Rydberg atoms. Resonances have been observed up to 340 GHz by harmonic generation (28th harmonic) from an X-band klystron).     

Rational harmonic mode-locking of erbium-doped fiber laser at 40 GHz using a loss-modulated Fabry-Pe/spl acute/rot laser diode

Rational harmonic mode-locking of an Erbium-doped fiber ring laser (EDFL) at repetition frequency of 40 GHz is demonstrated by using a purely loss-modulated Fabry-Pe/spl acute/rot laser diode (FPLD) at 1 GHz. The FPLD is neither lasing nor gain-switching, which requires a threshold modulation power of 18 dBm to initiate harmonic mode-locking of the EDFL. After chirp compensation, the nearly transform-limited pulsewidth and spectral linewidth of 3 ps and 1.3 nm are obtained at repetition frequency of 40 GHz, which corresponds to a time-bandwidth product of 0.31. The EDFL gradually evolves from harmonic mode-locking to injection-locking mode as the FPLD changes from loss-modulation to gain-switching mode by increasing its dc driving current.     

A W-band Third Harmonic Gyrotron with an Iris Cavity

The design and experimental results of a W-band gyrotron operating at the third cyclotron harmonic are presented. The gyrotron is designed to operate at the TE₆₁ mode, which is significantly distinct from competing modes. An iris cavity is employed for the purpose of trapping the third harmonic mode more effectively and lowering its start current. In the experiment, the gyrotron is drived by a triode magnetron injection gun (MIG) which can produce a 45 kV, 3 A electron beam. When maximum axial magnetic field is 1.22 T, a single mode third harmonic gyrotron radiation is observed with the frequency of 94.86 GHz. The maximum output power is 5.5 kW, corresponding to an efficiency of 4%. Another third harmonic mode TE₀₂ is also detected at 88.8 GHz, with maximum output power of 1.5 kW.     

An implementation of harmonic-suppression microstrip filters with periodic grooves

In this paper, a new parallel-coupled-line microstrip band pass filter (BPF) improving the harmonic suppression performance of the second harmonic signal (2f/sub o/, twice the passband frequency) is described. It is found that the desired passband performance is improved and the harmonic passband signal is diminished by enforcing the consecutive patterns in coupled-line and increasing the number of grooves to the optimum values. The recalculation of design parameters such as space-gap between lines, line widths and lengths is not required due to the simple modification of the conventional filter by inserting periodic patterns. To evaluate the validity of this novel technique, order-3 Butterworth BPF centered at 2.5 GHz with a 10% fractional bandwidth (FBW) and order-5 Chebyshev BPF centered at 10 GHz with a 15% FBW were used. When five and three square grooves are used, over 30-dB suppression at second harmonic signal is achieved in simulation and experiment. Finally, the comparison between the characteristics of filters with square and semicircular periodic grooves has been carried out by using the simulated results.     

High-harmonic content in trapped-plasma-mode oscillators

A waveguide-coaxial cavity has enabled efficient trapped-plasma-mode harmonic generation to be extended into the K band. A power of 2 W at 3.8% efficiency was obtained at the 12th harmonic of a 1.67 GHz fundamental. The use of a lamellar grating far-infrared interferometer with a novel gated detection system verified the presence of components up to 40 GHz, a frequency corresponding to three times the normal transit-time frequency.     

基于肖特基二极管的670 GHz四次谐波混频器设计

常温固态太赫兹谐波混频器是太赫兹系统应用中的关键器件。介绍了一款基于肖特基二极管的670 GHz四次谐波混频器的仿真与设计。在高频结构仿真软件(HFSS)中对准垂直结构肖特基势垒变阻二极管进行三维结构建模,采用基于谐波平衡算法的整体综合仿真方法对混频器进行仿真和优化。结果表明：在功率为10 mW的167 GHz本振信号驱动下,混频器单边带变频损耗在637~697 GHz射频频率范围内小于13.8 dB,3 dB变频损耗带宽为60 GHz;最优单边带变频损耗在679 GHz为10.6 dB。     

具有谐波抑制功能的宽带圆极化宽缝天线

针对微波无线输能系统中接收天线质量轻、体积小、剖面低、易与微波电路集成的特点,设计了一款新型的具有谐波抑制功能的宽带圆极化宽缝接收天线。通过在长方形缝隙中添加末端具有圆形贴片的交叉结构实现圆极化性能,添加切角结构展宽圆极化带宽。在馈线上添加具有一定长度的开路支节,配合使用缺陷地结构共同实现谐波抑制功能。研究并测试了天线的反射系数、轴比、增益以及远场辐射方向图,仿真与实测基本吻合。仿真结果显示,该天线很好地抑制了基频5.8 GHz的二次谐波和三次谐波,在4.5~6.2 GHz的范围内S11<-10 dB,相对阻抗带宽31.8%;基频5.8 GHz处的轴比AR=1.3 dB,在频率范围4.2~6.15 GHz内轴比AR<3 dB,相对轴比带宽37.7%;基频5.8 GHz仿真增益6.7 dB。     

High Power Gyro-Devices for Plasma Heating and Other Applications

Gyrotron oscillators are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. The maximum pulse length of commercially available 1 MW gyrotrons employing synthetic diamond output windows is 5 s at 110 GHz (CPI and JAERI-TOSHIBA), 12 s at 140 GHz (FZK-CRPP-CEA-TED) and 10 s at 170 GHz (GYCOM and JAERI-TOSHIBA), with efficiencies slightly above 30%. Total efficiencies of 45–50 % have been obtained using single-stage depressed collectors (SDC). The energy world record of 160 MJ (0.89 MW at 180 s pulse length and 140 GHz) at power levels higher than 0.8 MW has been achieved by the European FZK-CRPP-CEA-TED collaboration at FZK. Operation at the 1^st and the 2^nd harmonic of the EC frequency enables gyrotrons to act as medium power step-tunable mm- and sub-mm wave sources in the frequency range from 38 GHz (fundamental) to 889 GHz (2nd harmonic) for plasma diagnostics, EC plasma discharges for generation of multi-charged ions, high-frequency broadband electron paramagnetic resonance (EPR) spectroscopy and medical applications. Gyrotrons have also been successfully used in materials processing. Such technological applications require gyrotrons with the following parameters: f ≥ 24 GHz, P_out = 4–50 kW, CW, η ≥ 30%. Future applications which await the development of novel high-power gyro-amplifiers include high resolution radar ranging and imaging in atmospheric and planetary science as well as deep-space and specialized satellite communications and RF drivers for next-generation high-gradient linear accelerators (supercolliders). The present paper reviews the state-of-the-art and future prospects of gyro-devices and their applications.     

Millimeter wave semiconductor diode detectors, mixers, and frequency multipliers

The devices described include video detectors, mixers, harmonic mixers, and harmonic generators. A general discussion of the theoretical potential and limitations of these diodes is given, based on the equivalent circuit representation. This model is shown by experimental results to be valid up through 600 GHz. Diode materials, structures and forming techniques are described which have resulted in significantly improved electrical performance, as well as improved reliability and repeatability. Experimental results are quoted for detector sensitivities from 70 through 420 GHz, fundamental mixer conversion losses from 35 through 300 GHz, harmonic mixer conversion losses from 93 through 600 GHz, and harmonic generation efficiencies from fundamental frequencies of 60 through 140 GHz. The repeatability of mixer performance indicates that construction of balanced mixers is now feasible throughout the millimeter wavelength region. The improved harmonic mixer conversion losses permit construction of practical superheterodyne receivers at frequencies where local oscillator sources are impractical or unavailable. The harmonic generation capability at high frequencies (for example, at 140 GHz, one mW with diodes in the variable resistance mode and 15 mW with diodes in the varactor mode) is seen to permit the extension of frequencies for solid-state oscillators. If full advantage is taken of the capabilities of these devices, a large variety of millimeter wave systems can be assembled, including high resolution raders, high thermal sensitivity radiometers, broad bandwidth communication systems, as well as laboratory systems for mearsurement use or spectroscopic studies.     

Waveguide/resonant-disc circuits for millimetre-wave devices

Bias circuits using resonant discs have been employed for millimetre-wave transferred-electron (TE) diodes operating at their second or third harmonic frequencies in the V (50?75 GHz) and W (75?110 GHz) bands. It is shown that this type of circuit exhibits resonances at frequencies in the lower millimetre-wave range, corresponding to the fundamental oscillation frequency of diodes typically used. In addition, the circuit provides efficient coupling to the waveguide circuit at the higher (harmonic) operating frequency. By tuning the fundamental oscillation frequency of a number of resonant discs, the power-frequency spectrum of the TE device can be determined, which is demonstrated for a device with its maximum third-harmonic power output at 94 GHz.     

基于40 nm CMOS工艺的高效率功率放大器设计

针对硅基毫米波功率放大器存在的饱和输出功率较低、增益不足和效率不高的问题,基于TSMC 40nm CMOS工艺,设计了一款工作在28GHz的高效率和高增益连续F类功率放大器。提出的功率放大器由驱动级和功率级组成。针对功率级设计了一款基于变压器的谐波控制网络来实现功率合成和谐波控制,有效地提高了功率放大器的饱和输出功率和功率附加效率。采用PMOS管电容抵消功率级的栅源电容,进一步提高线性度和增益。电路后仿真结果表明,设计的功率放大器在饱和输出功率为20.5dBm处的峰值功率附加效率54%,1dB压缩点为19dBm,功率增益为27dB,在24GHz~32GHz频率处的功率附加效率大于40%。