Bandpass Filter

In this work we predict the nonlinear behaviour of an eight-pole quasi-elliptic bandpass high temperature superconducting (HTS) filter with an equivalent circuit extracted from intermodulation measurements performed at the centre of the filter passband. We present measurements that show that the equivalent circuit is able to predict the intermodulation products produced by the filter when driven by two in-band or out-of-band sinusoidal signals. Numerical techniques based on harmonic balance are used to extract the elements of the equivalent circuit and to simulate its nonlinear performance.

The paper describes a new principle of independent frequency and quality factor tuning suitable for simulated inductors based active RF filters. The method makes use of two dc decoupled negative resistances in order to avoid frequency and quality factor inter-dependency. A differential architecture is studied and several considerations regarding the tuning capability and stability behavior are presented. The target application is a multi-standard active bandpass filter envisaging wireless transceivers.

The design and analysis of a novel wideband, monolithic, bandpass, π π π π-network, voltage controlled attenuator (VCA) is presented. A 24 to 32 GHz VCA was developed using 0.15µ µ µ µm GaAs pHEMT technology. This is the first reported VCA to use a bandpass filter topology to achieve the required operating frequency band and eliminate the effects of parasitic capacitances of the pHEMTs. The bandpass filter absorbs the parasitic capacitances and thereby eliminates their detrimental effects. The measured attenuation dynamic range is 12dB ± ± ± ± 0.5dB with minimum insertion loss of 2-3dB. The input power handling capability is up to 0dBm. The VCA is well matched and may be placed in a 50Ω Ω Ω Ω system [1].

The design and analysis of a novel wideband, monolithic, bandpass, π π π π-network, voltage controlled attenuator (VCA) is presented. A 24 to 32 GHz VCA was developed using 0.15µ µ µ µm GaAs pHEMT technology. This is the first reported VCA to use a bandpass filter topology to achieve the required operating frequency band and eliminate the effects of parasitic capacitances of the pHEMTs. The bandpass filter absorbs the parasitic capacitances and thereby eliminates their detrimental effects. The measured attenuation dynamic range is 12dB ± ± ± ± 0.5dB with minimum insertion loss of 2-3dB. The input power handling capability is up to 0dBm. The VCA is well matched and may be placed in a 50Ω Ω Ω Ω system [1].

We report on a 275-425-GHz tunerless waveguide receiver with a 3.5-8-GHz IF. As the mixing element, we employ a high-current-density Nb-AlN-Nb superconducting-insulatingsuperconducting (SIS) tunnel junction. Thanks to the combined use of AlN-barrier SIS technology and a broad bandwidth waveguide to thin-film microstrip transition, we are able to achieve an unprecedented 43% instantaneous bandwidth, limited by the receiver's corrugated feedhorn. The measured double-sideband (DSB) receiver noise temperature, uncorrected for optics loss, ranges from 55 K at 275 GHz, 48 K at 345 GHz, to 72 K at 425 GHz. In this frequency range, the mixer has a DSB conversion loss of 2.3 1 dB. The intrinsic mixer noise is found to vary between 17-19 K, of which 9 K is attributed to shot noise associated with leakage current below the gap. To improve reliability, the IF circuit and bias injection are entirely planar by design. The instrument was successfully installed at the Caltech Submillimeter Observatory (CSO),

We report on the development of some of the key technologies that will be needed for a large-format Cosmic Microwave Background (CMB) interferometer with many hundreds of wideband W-band (75-110 GHz) receivers. A scalable threebaseline prototype interferometer is being assembled as a technology demonstration for a future ground-or space-based instrument. Each of the prototype heterodyne receivers integrates two InP Monolithic Microwave Integrated Circuit (MMIC) low-noise amplifiers, a coupled-line bandpass filter, a subharmonic balanced diode mixer, and a 90 • local oscillator phase switch into a single compact module that is suitable for mass production. Room temperature measurements indicate bandaveraged receiver noise temperatures of 500 K from 85-100 GHz. Cryogenic receiver noise temperatures are expected to be around 50 K.

Millimeter-wave (mm-wave) bandpass filters are presented using the standard 0.18-µm CMOS process. Without any postprocessing steps, thin film microstrip (TFMS) structure is properly constructed on the low-resistivity silicon substrate, aiming at reducing the substrate loss and crosstalk to a large extent. Using the broadside-coupled scheme, a tight coupling is achieved so as to make up a class of low-loss and broadband TFMS bandpass filters in the mm-wave range. To achieve a small size, one-stage and two-stage filters with sinuous-shaped resonators are designed and fabricated. A good agreement between the predicted and measured results has been observed up to 110 GHz.

Three properties are defined for information I: the null state, equivalence judgment, and inversion. Two types of operational elements are defined: the delay circuit F D and the NOT operation circuit. By combining these elements, discrete oscillation patterns and propagation patterns are constructed, and it is shown that the formulation of each takes mathematically identical forms to the formulas for simple harmonic oscillation, uniform propagation, and the fundamental vibration of a string. This paper contains no physical claims and deals solely with the consistency of the model as a computational framework.

Waveguides are robust structure and handle high power well, compared to transmission line filter such as coplanar lines, microstrips and striplines. As such, it is used in a very small aperture terminal (VSAT) communication system operating at C-band. In this paper, the mathematical computations for the design dimensions of a direct-coupled cavity waveguide bandpass filter are implemented using MathCAD mathematical software, based on the insertion loss method. Firstly, the design specifications are set. These include operating frequency, operating bandwidth, minimum attenuation, ultimate attenuation, and type of filter response. An optimum number of filter orders will be determined. The cavity waveguide filter consists of vertical inductive diaphragm of circular holes, which represent the cavity. Computation of the filter performances in terms of the insertion and return losses were successfully achieved. Comparisons with electromagnetic simulations were also made. Good correlation can be observed between the computed performances using MathCAD and simulated performances using simulation software

This paper presents the design of a compact, internally-coupled hairpin-line bandpass filter based on resonator elements. Investigations on the dimension parameters were performed using electromagnetic simulation software. The parameters that affect the filter performances were identified. From the investigations carried out, it was found that the design dimensions can be fine-tuned for optimization and hence achieved the desired specifications. In addition, the performance of the proposed miniaturized internally-coupled hairpin-line design is comparable to a corresponding conventional hairpin-line configuration, albeit exhibiting 46% reduction in size.

A CMOS active inductor that has a large quality factor and independent L and Q tuning capability is presented. The tunable active inductor has 0.8 V supply voltage. In this voltage this TAI shows a quality factor equal to 11400 and power dissipation of 1.8 mW. It has 1.4 GHz inductive bandwidth. The TAI has an interesting property that has an independent inductance and quality factor tuning.

In this study, performance evaluation, drying kinetics modelling and economic analysis of locally manufactured rice husk-fueled mixed-flow rice dryer were investigated. The dryer had a size of 0.4 × 0.4 × 0.64 m (width, length, and height) with a holding capacity of 30 kg in a batch. The drying air used had a volume flow rate of 0.06 m 3 /s, with an average drying air velocity of 0.62 m/s within the drying section. The average temperature recorded during the experiment was 49.5 ± 3.1℃ at the dryer inlet, while the ambient air temperature was 26.4 ± 0.2℃. The dryer was able to reduce the moisture content of the sample rice from 20.9 % (wet bases) to 12 % (wet bases) in 3 h and 10 min, achieving an average drying rate of 0.076 kg water per minute or 0.016 kg water per kg dry matter per minute. In order to achieve this drying rate, the average energy consumption was 37.9 MJ with an average of 54.29 % dryer efficiency. The Modified Henderson & Pabis was the best drying model to predict the drying kinetics in this study among the different thin-layer drying models. The milling quality of the dry product was assessed using the Head Rice Yield (HRY). The HRY was found to be 57.4 ± 0.62 % for long and slender Nerica-4 rice cultivars, the result was above the required customer requirement which is 55 % and more. Furthermore, the economic analysis indicated that the payback period for the developed rice husk-fueled mixedflow dryer for drying rice was 1.4 years. The dryer, which costs 64,213ETB (approximately USD 1,230) has the potential to significantly reduce postharvest loss and enhance food security and income of smallholder farmers in rural off-grid areas.

This work presents a miniaturized bandpass filter in V-band using integrated passive device (IPD) technology with thick metal layers and Benzocyclobutene (BCB) dielectric on a glass substrate. The proposed filter, comprised of two stepped-impedance resonators with quarter-wave short-circuited stubs and floating pads, has low passband insertion loss and high stopband attenuation in a compact size. The fabricated filter has an insertion loss of 2.46 dB at the center frequency of 59 GHz, and a 3 dB bandwidth from 55.7 to 62.2 GHz. The core size of this filter is only 0.32 0.4 mm 2 (0 064 0 08 2 0 ).

In this paper, a linearity improvement technique is proposed for a low-distortion { bandpass filter operating in high IF ranges. The proposed transconductor eliminates value at the output by superposing the opposite non-linear behaviors of two differential structures in parallel. For the bandpass filter, instead of conventional biquad structure, a resonant-coupling structure is adopted for a flat frequency response which is insensitive to process and temperature variations. Fabricated in 65 nm CMOS process, the implemented 80 MHz bandpass filter shows a flat bandpass characteristic with 0.1 dB ripple, third-order harmonic rejection of 27 dB, IIP3 of 2 dBm, and NF of 21.5 dB, while consuming 11 mA from 1.2-V supply. The filter occupies the chip size of 0.5 0.5 mm 2 .

In this paper, a new microstrip interdigital even-mode half-wavelength type stepped impedance resonator (SIR) based bandpass filter (BPF) for I-band applications is presented. The bandpass filter characteristic depends on the self-resonant frequency of the interdigital resonated arms. The combination of the interdigital arm structures behaves as an interdigital capacitance coupling between port 1 and port 2. The self generated capacitive and inductive reactances of the interdigital resonators interacted in order to obtain a resonance at 9.4 GHz. The resonant frequency and the bandwidth of the filter are directly optimized as a result of the physical arrangement of the interdigital resonators. The measured insertion loss (S21) and the return loss (S11) are –0.85 dB and –28.0 dB, respectively, at the 9.4 GHz resonant frequency.

Using observations of the corona taken during the total solar eclipses of 2006 March 29 and 2008 August 1 in broadband white light and in narrow bandpass filters centered at Fe x 637.4 nm, Fe xi 789.2 nm, Fe xiii 1074.7 nm, and Fe xiv 530.3 nm, we show that prominences observed off the solar limb are enshrouded in hot plasmas within twisted magnetic structures. These shrouds, which are commonly referred to as cavities in the literature, are clearly distinct from the overlying arch-like structures that form the base of streamers. The existence of these hot shrouds had been predicted by model studies dating back to the early 1970s, with more recent studies implying their association with twisted magnetic flux ropes. The eclipse observations presented here, which cover a temperature range of 0.9 to 2 ×10 6 K, are the first to resolve the long-standing ambiguity associated with the temperature and magnetic structure of prominence cavities.

In this paper, neural network modeling techniques are applied to the design of waveguide dual-mode pseudo-elliptic filter. A hybrid modeling approach is developed where neural networks and filter coupling matrix are combined in an innovative way to deliver speed and accuracy of the overall filter design. Filter structure is decomposed into modules representing each coupling mechanism. Generalized scattering matrices (GSM) of the modules are calculated using mode-matching method. Equivalent circuit parameters, such as coupling value and insertion phase lengths are then extracted from EM data. Neural models are developed for circuit parameters for each individual module instead of direct modeling of GSM. Good agreement is obtained between neural models and EM-based data. A narrow-bandwidth four-pole Ku band bandpass filter is designed using the trained NN models, and simulated and optimized using full EM model (HFSS). The difference between the optimized dimensions and NN model is within 0.01" for all dimensions, which demonstrates that the developed NN models are capable of achieving the accuracy of EM-based model with superior computation speed.

In this paper, systematic neural network modeling techniques are presented for microwave modeling and design using the concept of inverse modeling where the inputs to the inverse model are electrical parameters and outputs are geometrical parameters. Training the neural network inverse model directly may become difficult due to the nonuniqueness of the input-output relationship in the inverse model. We propose a new method to solve such a problem by detecting multivalued solutions in training data. The data containing multivalued solutions are divided into groups according to derivative information using a neural network forward model such that individual groups do not have the problem of multivalued solutions. Multiple inverse models are built based on divided data groups, and are then combined to form a complete model. A comprehensive modeling methodology is proposed, which includes direct inverse modeling, segmentation, derivative division, and model combining techniques. The methodology is applied to waveguide filter modeling and more accurate results are achieved compared to the direct neural network inverse modeling method. Full electromagnetic simulation and measurement results of -band circular waveguide dual-mode pseudoelliptic bandpass filters are presented to demonstrate the efficiency of the proposed neural network inverse modeling methodology.

1.0 Introduction 2.0 Heuristic Beginnings 2.1 The Power Spectrum and Quadratic Estimators Accession For I TI RA&I 2.2 ideal Filters D? 7, I U . *•:.i ," '.'., a d LI 2.3 Complex Demodulation and Frequency Sweeping J : £ '.mt io 2.4 FIR Filters