High Harmonic Suppression Research Articles

2.8 dB conversion gain broadband HBT–HEMT balanced frequency tripler with high harmonic suppression

A 10.2-12.6 GHz balanced heterojunction bipolar transistor (HBT)-high electron mobility transistor (HEMT) frequency tripler is presented. A pair of common-base/common-emitter HBTs is used to generate in-phase and out-of-phase harmonics. Two bandpass filters are utilised as matching networks to enhance the harmonic suppression. A common-gate/common-source HEMT active balun is employed to combine the third harmonic in-phase and provide conversion gain. The proposed frequency tripler shows a conversion gain of 2.8 dB, a fractional bandwidth of 21.2% and a fundamental suppression higher than 47 dB.

Optimised high‐efficiency Class E radio frequency power amplifier for wide bandwidth and high harmonics suppression

A Class E power amplifier offers high efficiency approaching 100% for an ideal case. A new wide bandwidth Class E power amplifier design has been introduced combining a parallel-circuit load network with reactance compensation technique and high-order harmonic suppression circuit. The proposed topology has been discussed based on theory and its experimental verification. A hardware prototype was designed and built, and measurement results showed drain efficiency of 70% and second harmonic rejection of more than 84 dBc (as well as higher harmonics), and output power level more than 6.5 W with ±0.5 dB power flatness, across very high frequency (VHF) band (136-174 MHz). The performance achieved demonstrated highest harmonic suppression across wide bandwidth for VHF range according to authors' knowledge. Simulations of power performance (i.e. efficiency and output power) were verified by measurements, and good agreements were obtained.

A power parallel active filter with higher efficiency

A new approach to expanding the suppression band and reducing the power losses in a parallel active filter by incorporating an additional corrective linear link into its structure, taking into account a delay in the interface filter, and minimizing the switching frequency of inverter power keys is developed. An algorithm of controlling the corrective link that allows increasing the performance of AF and improving the suppression of higher harmonics is proposed.

Structure Design and Properties of Amorphous Filter Reactors

Five filter reactors as tools for higher harmonics suppression in the power system were fabricated with Fe based soft magnetic amorphous ribbons. The fabrication processes that combine amorphous core winding, heat treatment, dipping, drying, cutting, and assembling were performed to obtain low core loss amorphous reactors. The properties of the reactors are investigated in detail in this article. Experiments results indicate that the core losses of the amorphous reactor cores are far lower than that of silicon steel reactors cores. At the same time, the core temperature rises of the amorphous reactors are also smaller and the noise levels of the reactors accord to the requirement for sale. Altogether, the Fe-based amorphous ribbons can be successfully used to fabricate low loss reactor cores.

Dual-Loop Power Control for Single-Phase Grid-Connected Converters with LCL Filter

Grid-connected converters have widely adopted LCL filters to acquire high harmonic suppression. However, the LCL filter increases the system order so that the design of the system stability would be complicated. Recently, sole-loop control strategies have been used for grid-connected converters with L or LC filters. But if the sole-loop control is directly transplanted to grid-connected converters with LCL filters, the systems may be unstable. This paper presents a novel dual-loop power control strategy composed of a power outer loop and a current inner loop. The outer loop regulates the grid-connected power. The inner loop improves the system stability margin and suppresses the resonant peak caused by the LCL filter. To obtain the control variables, a single-phase current detection is proposed based on PQ theory. The system transfer function is derived in detail and the influence of control gains on the system stability is analyzed with the root locus. Simulation and experimental results demonstrate the feasibility of the proposed control.

Oscillator with High Harmonic Suppression Using Split Quarterwave Microstrip Resonator

This letter presents a new type of resonator, namely, the split quarterwave microstrip resonator (SQMR), to improve the poor harmonic suppression and low Q-factors in conventional quarterwave microstrip resonators. An oscillator incorporating the proposed SQMR is designed, fabricated, and tested to demonstrate that, not only the second harmonic suppression, but also the phase noise of the oscillator can be improved. The oscillator with the SQMR shows improved second harmonic suppression of –74.59 dBc and phase noise figure of merit of –169.77 dBc/Hz at 1 MHz offset.

兼具高次谐波抑制的三镜偏振器

兼具高次谐波抑制的三镜偏振器

Compact CPW-fed ground defected H-shaped slot antenna with harmonic suppression and stable radiation characteristics

A compact uniplanar antenna for 2.4 GHz WLAN applications is presented. This compact co-planar waveguide (CPW)-fed antenna has an advantage of excellent higher harmonic suppression. This characteristic is brought about by suitably inserting symmetrical slots in the ground plane of an open-ended CPW-fed transmission line. The proposed antenna with an H-shaped slot exhibits the characteristics of a centre-fed slot dipole together with excellent higher-harmonic suppression. The antenna designed on a substrate of dielectric constant 4.4 and height 1.6 mm offers moderate gain and good radiation characteristics. The design equations for the proposed antenna are validated in different frequency bands. Details of the simulated and experimental characteristics of the antenna are presented and discussed.

Compact rat‐race ring coupler with capacitor loading

AbstractA simple compact microstrip rat‐race ring coupler with capacitor loading is presented in this letter. The new coupler not only effectively reduces the occupied area to 15% of the conventional one at 1.0 GHz, but also has high harmonic suppression performance over a wide band. Furthermore, the new structure has only two variable parameters and can be easily designed. The design is validated both by simulation and measurement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 7–9, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24823

Compact power dividers embedded with LCL and CLC units

Compact power dividers embedded with LCL and CLC units are presented. Compared with the LCL type power divider, the CLC type power divider not only occupies less area, but has high harmonic suppression performance over a wide band. The design is validated both by simulation and by measurement.

Compact Microstrip Ring Branch-Line Coupler with Harmonic Suppression

A novel ring branch-line coupler is presented in this paper. To minimize the physical size of the coupler, four high-low impedance resonator cells are loaded within the free area of the conventional coupler. A design methodology calling for united optimization is used to optimize the structure parameters of the main transmission lines and loading high-low impedance resonators. Furthermore, an equivalent circuit of one loaded cell is proposed to model the operation of the coupler. The proposed new coupler not only effectively reduces the occupied size to 22% of the conventional one at the operating frequency of 1.39 GHz, but also has high third harmonic suppression.

Optical polarizer integrated with suppression of higher harmonics in the vacuum ultraviolet and soft x-ray spectral regions

Based on a concept of Au–Si–Au triple reflection, we present a low pass polarizer that suppresses higher-order harmonics from vacuum ultraviolet and soft x-ray monochromators. By appropriate optimization of the material and the angle of incidence, the polarizer enables the possibility to tune its cutoff edge of photon energy, and therefore to suppress higher-order diffraction light. Vacuum ultraviolet ellipsometry experiments with BESSY II synchrotron radiation in 9–23eV have demonstrated the suppression of higher-order harmonics.

A Compact Slow-Wave Microstrip Branch-Line Coupler With High Performance

One compact slow-wave microstrip branch-line coupler is presented. The new structure not only effectively reduces the occupied area to 28% of the conventional branch-line coupler at 2.0 GHz, but also has high second harmonic suppression performance. The measured results indicate a bandwidth of more than 200 MHz has been achieved while the phase difference between S21 and S31 is within 90deg plusmn 1deg. Furthermore, the measured insertion loss is comparable to that of a conventional branch-line coupler. The new coupler can be easily implemented by using the standard printed-circuit-board etching processes and is very useful for wireless communication systems.

Novel resonator based on composite right/left-handed transmission lines

A new approach was introduced to analyze composite right/left-handed transmission lines (CRLH TLs). The Bloch impedance and the dispersion relations are directly obtained from the S parameters of the unit cells. The LH and RH frequency bands are then identified by the real parts of the Bloch impedance and the phase delay of the unit cells. The new approach has some advantages over the LC parameters extraction method introduced by Caloz et al.(2004). Based on the new approach, a novel resonator is designed using CRLH TLs. The simulation and experimental results accorded well with the theoretical analysis. The novel resonator may have potential applications in filters with high harmonic suppression and compact structures.

Ultrasonic piezoceramic motor: The computation of traveling-wave velocity on the stator surface and excitation by PWM modulation with higher harmonic suppression

The article describes operating principle of traveling-wave piezoelectric ultrasonic motor. This motor makes use of the fact that when a surface traveling wave propagates along finite elastic body of the stator, the rotor is driven due to the friction between the stator and the rotor. The main part of this paper is focused on the computation of traveling-wave speed on the surface of piezoceramic transducer. Furthermore, the methods of the ultrasonic piezoceramic motors driving are presented. In detail there are described the possibilities of feeding by the nonharmonic signals, particularly by the pulse width modulation (PWM). The proportion of pulse width to the turn-off interval is selected with the stress on higher harmonic suppression. This way of ultrasonic piezoceramic drive controlling reduces reactive input power and increases efficiency. The realization of the control system by means of field programmable gate array (FPGA) and digital signal processing is introduced too.

New configurations of single‐ and multi‐level bandpass filters with excellent harmonic suppression

AbstractNew configurations of high‐frequency quasi‐lumped capacitive configurations and composite structures with application to bandpass filters are presented. These structures show distinct advantages that facilitate compactness and higher harmonic suppression and have been analyzed according to suitable network models. Simple design equations have been used to synthesize new filter configurations, which exhibit excellent higher‐order harmonic suppression. The proposed new designs have been validated by measurement. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 490–493, 2003

Bistability and stochastic resonance in an open quantum system

We give a detailed analysis of bistability and the associated time scales in a fundamental, driven, open quantum system, the micromaser. Under certain conditions, the quantized, nonclassical photon field in the maser cavity exhibits quantum jumps between two metastable states. We show how to calculate the corresponding transition rates, examine the influence of an injected atomic coherence, and discuss different measurement schemes to detect the final state of the exiting atoms. With these results, noise-induced effects such as stochastic resonance or suppression of higher harmonics can be understood.

Bulk micromachined electrostatic RMS-to-DC converter

Bulk micromachining in silicon and glass wafers and subsequent silicon-to-glass anodic bonding have been used for the realization of an electrostatic RMS-to-DC converter. A suspended membrane has been designed for: large dynamic operating range (detection limit by minimum mechanical-thermal noise and high value of the pull-in voltage), maximum bandwidth (low series resistance, high second harmonic suppression using squeeze film damping and suspension beam design), long-term stability, and a sufficient displacement-to-voltage sensitivity (membrane area and suspension arm length). Prototypes are typically composed of a 3 /spl times/ 3 mm/sup 2/ perforated membrane area suspended by four beams of 200 /spl mu/m length, 500 /spl mu/m width, and 4 /spl mu/m thickness micromachined out of silicon and aligned to a counter electrode on glass with 4-/spl mu/m spacing in between. Measurements on realized devices show a 4.5 pF nominal capacitance. Static measurements indicate a sensitivity of 5 fF/V/sup 2/ and a voltage shift of 0.2 V. The nominal square relation is achieved within a 0.5% nonconformity error.

Enhancement of the Q of a nonlinear acoustic resonator by active suppression of harmonics

Finite-amplitude stationary acoustic waves in a closed resonator subjected to simultaneous excitation at fundamental frequency and its second harmonic are analyzed in the frame of the second-order nonlinear theory. The conditions when the dual-frequency excitation leads to a quality factor Q higher than in the case of a single-frequency excitation are derived. The Q enhancement can be explained in terms of active suppression of cascade processes of the generation of higher harmonics. The second harmonic generated in the resonator is compensated by the second harmonic radiated by the piston. Suppression of higher harmonics also can be explained as being due to effective down conversion of energy from the second harmonic to the fundamental wave in the nonlinear parametric process.

Design of a dedicated beamline for x-ray microfocusing- and coherence-based techniques at the Advanced Photon Source

A dedicated insertion-device beamline has been designed and is being constructed at the Advanced Photon Source (APS) for development of x-ray microfocusing- and coherence-based techniques and applications. Important parameters considered in this design include preservation of source brilliance and coherence, selectable transverse coherence length and energy bandwidth, high beam angular stability, high order harmonic suppression, quick x-ray energy scan, and accurate and stable x-ray energy. The overall design of this beamline layout and the major beamline components are described. The use of a horizontally deflecting mirror as the first optical component is one of the main features of this beamline design, and the resulting advantages are briefly discussed.