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A novel terahertz (THz) waves band-pass filter with the center frequency of 880 GHz and low insertion loss using microstrip line hairpin resonators is introduced. The properties of this filter are investigated by finite element method (FEM) simulations. The numerical result shows that the filter has a 3 dB bandwidth from 865 GHz to 892 GHz and has 80 GHz bandwidth better than -10 dB. Resonance frequency shifts of the filter covered by dielectric materials of different permittivity and thickness are calculated, which shows that this type of filter is suitable for detecting the properties of overlaid dielectric materials.

A method to design a cross-coupled resonator filter with parallel resonance circuits is presented, which includes the selection of a circuit model, introduces a scaling factor and a bandwidth condition, and calculates the values of the coupling and resonance admittances of the circuit model by a coupling matrix derived from the given transfer function. Finally, an example is given to illustrate the design procedure. The simulation results validate the proposed design procedure.

One approach to design self-tuning g_m-C biquad band-pass filter is considered in this paper. The phase control loop is introduced to force filter central frequency to be equal to input signal frequency what is achieved by adjusting the amplifier transconductance g_m. Thanks to that, the filter is robust to parameter perturbations and it can be used as a selective amplifier. In the full tuning range, it has a constant maximum gain at central frequency as well as a constant bandwidth. The 0.25 μm SiGe BiCMOS technology was used during design and verification of the band-pass filter. The filter has 26 dB gain, quality factor Q = 20 and central frequency up to 150 MHz. Simulation results indicate that the total in-band noise is 59 μV_rms, the output third intercept point OIP3 = 4.36 dB and the dynamic range is 35 dB. Maximal power consumption at 3 V power supply is 1.115 mW.

In this paper, a frequency-tunable dynamic pulse integrating circuit for infrared receivers is presented. The proposed circuits possess many advantages, such as high sensitivity, high immunity against disturbances, simple structure, and so on. This integrator not only defines a minimum time for the burst length and a minimum time between the bursts, but also achieves the same minimum number of pulses in different frequencies. The frequency-tunable dynamic pulse integrator is a combined structure of the center frequency modulation and a new type of pulse integrator. The center frequency modulation is implemented by using zener zap anti-fuse trim and a second-order band-pass filter (BPF) with bipolar operational transconductance amplifier (OTA) cell. The integrator also describes the characteristics of variable-error tolerance to prevent the output envelope error due to the lack of individual pulses. The results of simulation are shown that the center frequency is available from 33 to 40 kHz and 56 kHz in typical application by Cadence respectively. Moreover, the minimum burst length is 10 pulses and minimum bursts gap time is 14 pulses in typical application.

The paper presents new single active element based second order band pass filters. The new circuits use single dual-X current conveyor with buffered output and five passive components. The proposed circuits enjoy the features of high input impedance and low output impedance, which are desirable features for voltage-mode circuits. Circuit operation at high frequencies are verified along with non-ideality and parasitic study. The Monte Carlo analysis is also done which justify good sensitivity performances of the proposed circuits. Routh–Hurwitz's stability test is performed to verify the stability of the proposed circuits. For showing the integration aspect, resistorless band-pass filters are also realized. The proposed low-Q filters are useful for cascading. The feature of cascadability is further utilized by showing an application of fourth-order band-pass filter. The performances of the proposed circuits are depicted through Personal Simulation Program with Integrated Circuit Emphasis (PSPICE) simulations, which show good agreement to theoretical applications. The new circuits are expected to enhance the already existing knowledge on the subject.

The aim of this paper is proposing an alternative method to Gorski-Popiel Technique in realization of synthetic transformers. A new synthetic floating transformer (FT) circuit is also given. The proposed synthetic transformer circuit uses two current backward transconductance amplifiers (CBTAs), three resistors, and two grounded capacitors. The primary self-inductance, the secondary self-inductance, and the mutual inductance can be independently controlled and can be tuned electronically by changing the biasing current of the employed CBTAs. It has a good sensitivity performance with respect to tracking errors. A band-pass filter is also realized to test the performance of the proposed synthetic transformer circuit. The validity of the proposed synthetic transformer circuit is demonstrated by PSPICE simulations and experimental results.

This paper describes the design of a novel cascode-grounded tunable active inductor and its application in an active band-pass filter (BPF) suitable for multi-band radio frequency (RF) front-end circuits. The proposed active inductor circuit uses feedback resistance to improve the equivalent inductance and the quality factor. The novelty of this work lies on the use of a few number of multi-finger transistors, which allows reducing strongly the power consumption and the silicon area. In other words, we demonstrate that the use of variable P-type Metal-Oxide-Semiconductor (PMOS) resistor and controllable current source have a good potential for wide tuning in terms of inductance value, quality factor and frequency operation. The RF BPF is realized using the proposed active inductor with suitable input and output buffer stages. The tuning of the center frequency for multi-band operation is achieved through control voltages. The designed active inductor and RF BPF have been implemented in a standard 0.13$\mu$m Complementary Metal Oxide Semiconductor (CMOS) technology. The simulation results are compared between schematic and post-layout design for inductance value, quality factor, transmission coefficient S21 and noise. This design yields encouraging results: the inductance value can be tuned from 10.94 to 44.17nH with an optimal quality factor around 2,581. In addition, the center frequency of the BPF can be tuned between 2 and 4.84GHz with an average insertion loss of $10.92\pm 0.31$dB. Throughout this range, the noise figure is between 10.49 and 9.22dB with an input referred 1dB compression point of $-0.25$dBm and IIP3 of 7.36dBm. The filter occupies 25.43$\mu \mathrm{\text{m}}\times 21.56\mu$m of active area without pads and consumes between 2.38 and 2.84mW from a 1V supplying voltage.

This paper presents a novel design of second-order triple band waveguide bandpass filter using planar insert technology. A conventional WR-90 rectangular waveguide has two identical inserts inserted into its transverse plane at an optimal spacing of 8.41mm. The insert consists of a combination of a double-split square resonator and a single split square resonator with stub. These resonators are used to achieve triple-band bandpass characteristics. The structure allows independent control of three center frequencies, insertion loss, return loss and 3-dB bandwidth. The simulation analysis of the proposed filter is carried out using the CST microwave studio, and its frequency response is compared with its equivalent circuit response. To validate the numerical analysis, the WR-90 waveguide and planar insert are fabricated independently and inserted manually. The dual-pole triple band bandpass characteristic of the manufactured filter, with center frequencies of 8.19, 9.39 and 11.09GHz, is shown by the measured data. The complete design process has also been provided, along with a corresponding circuit diagram. The suggested waveguide filter’s performance is evaluated against those found in the literature already.