Floating general immittance function simulator

In this paper, the effect of non-idealities of CFOA and G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf> -block used in a recently proposed impedance multiplier is studied. Since the CFOA is used in open-loop mode, the effect of series resistance of the CCII at x terminal, input impedance of the CCII at y terminal, the output impedance of the CCII at z terminal and the output impedance of the G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf> -block are analyzed. The effect of these non-idealities on applications of the capacitance multiplier to realize second-order low-pass, band-pass and notch filters using external resistance and inductance is studied in detail, SPICE simulation results are also provided. The proposed impedance multiplier is explored to realize a generalized immittance converter (GIC) using current conveyor, G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf> -block and two impedance elements. The immittance converter circuit is shown to realize various simulated grounded elements like positive/ negative inductor, resistance/ capacitance multiplier, frequency dependent negative resistor (FDNR) and super inductor etc.

In this article a new electronically controllable grounded frequency-dependent negative resistance (FDNR) simulation circuit is proposed. The presented circuit employs two voltage differencing current conveyors (VDCCs), two grounded capacitances and one grounded resistance. The proposed configuration simulates a grounded FDNR without any requirement of component matching and enjoys the electronic control through transconductances of VDCCs. The presented circuit exhibit excellent non-ideal behavior and low values of sensitivity figures. The high frequency limitation of realized configuration has been evaluated under the influence of parasitic impedances. The workability of the proposed FDNR has been confirmed by SPICE simulations using CMOS VDCC.

A new CMOS dual-X second generation current conveyor (DXCCII) with an FDNR circuit application

This paper describes switched-capacitor (SC) inductor and Frequency Dependent Negative Resistor (FDNR) which use second generation current conveyor (CC II). In general CC II's used in SC circuits are not always used as CC II and there are phase periods in which CC II behaves as much simpler active device like unity gain buffer (UGB). In this paper, CC II's in SC circuits always behave as CC II to make full use of CC II. Then an SC inductor in which effects of parasitic capacitors can be reduced is proposed. And SC FDNR which uses CC II to get a simple circuit structure is also proposed. Both circuits are controlled by simple two-phase control clock. The spreads of capacitor values are 1. The sum of capacitor values of SC FDNR is 4. This value is the smallest reported value in SC FDNR circuits. Simulation results by SWITCAP and experimental results by discrete components are shown.

This paper presents a novel connecting-line coupling technique for the design of compact and low-loss bandpass filters (BPFs) with multiple controllable transmission zeros (TZs). Traditional gap-coupling methods are highly sensitive to fabrication errors and have limited design flexibility. By contrast, the proposed approach enables precise control of coupling strength without modifying resonator geometry. Such control is achieved through independent adjustments of the lengths, widths, and positions of connecting lines. Furthermore, the proposed approach facilitates the generation of up to n TZs for an nth-order BPF, thus considerably improving the BPF’s frequency selectivity and stopband attenuation. To validate the effectiveness of this method, four filters are designed and fabricated: a second-order stripline BPF, a fourth-order microstrip BPF, a fifth-order stripline BPF, and a sixth-order wideband microstrip BPF. The second-order BPF is based on asymmetric connecting-line coupling, whereas the fourth-, fifth-, and sixth-order BPFs are based on symmetric connecting-line coupling. Excellent agreement between simulation and measurement results is achieved for these designs, with low insertion loss, high roll-off rates, and high tolerance to fabrication variations being noted. The proposed technique is suitable for filters ranging from narrowband to ultra-wideband filters and across low to millimeter-wave frequency bands, making it a highly versatile and practical solution for modern RF and microwave communication systems.

The purpose of this paper is to present ground frequency dependent negative resistance (FDNR) using voltage differencing differential input buffered amplifier (VDDIBA) active element. The presented FDNR circuit is developed using two VDDIBAs, two capacitors and a single resistor, the use of VDDIBA in FDNR implementation has not been reported in open literature so far. Therefore, this work can be considered as a base for future research in this area. The presented realization offers electronic control of simulated negative resistance value through the biasing current of used VDDIBAs. There is no requirement for matched active/passive component in this design with low sensitivity indexes. In order to verify the behaviour of the presented configuration, the band reject and bandpass filter design examples have been developed. All the presented circuits have been tested by PSPICE simulation tool. For simulation purposes, the VDDIBA has been implemented by CMOS OTA and AD844 CFOA.

This paper introduces a new floating simulator suitable for realizing frequency dependent negative resistor (FDNR). The introduced FDNR uses three current feedback operational amplifiers and a canonical number of passive components. It does not need any passive component matching conditions and/or cancellation constraints. In addition, a voltage-mode band-pass filter is given as an application example. Simulation results are also comprised to affirm the theory.

In this paper, we design and fabricate a coplanar waveguide (CPW) bandpass filter operating at 60 GHz. A new DGS pattern is proposed and serves as the unit cell. We cascade two unit cells to construct a second-order bandpass filter. The equivalent lumped element circuit model was extracted form the full-wave electromagnetic simulation. Moreover, we obtain good agreement between circuit model analysis and simulation. The measurement results for the proposed bandpass filter reveals a 3 dB pass band with a bandwidth of 6.8 GHz. Furthermore, the insertion loss at 60 GHz is less than 2 dB.

A switched-capacitor filter using a frequency-dependent negative resistance (FDNR) is described. FDNR filters closely simulate passive LC filters, thereby retaining passband stability and design simplicity. The filter has been implemented in LSI and designed to perform the transmit/receive filtering for PCM codecs. Circuits are described that overcome the floating node and floating amplifier problems previously associated with FDNRs.

A new class of bandpass filters with quasi-elliptic frequency response, small physical size, and effective quality factors $(Q{\bf s}_{\bf eff})$ of the order of 1000 are presented. They are based on novel hybrid acoustic-wave-lumped-element resonator (AWLR) modules that enable the realization of bandpass filters with fractional bandwidths (FBWs) that are much larger (0.91–5.1 $k_{t}^{2}$ ) than the electromechanical coupling coefficient $(k_{t}^{2})$ of conventional acoustic wave (AW) resonator filters that exhibit FBWs between 0.4–0.8 $k_{t}^{2}$ . In addition, they exhibit $Q{\bf s}_{\bf eff}$ that are 25–50 times larger than in traditional lumped-element filter architectures. Quasi-elliptic single-pole bandpass filters (one pole and two zeros) made up of commercially available one-port surface AW resonators and surface-mount-device components are manufactured and measured at 418 MHz. Various passbands with FBW between 0.07% and 0.4% and insertion loss below 1.25 dB (i.e., $Q{\bf s}_{\bf eff}$ in the range of 1525–5150) are demonstrated. Second-order bandpass filters (two poles and four zeros) with 0.24% FBW and less than 1.15 dB of insertion loss (i.e., $Q{\bf s}_{\bf eff}$ of 4000) are also shown to improve the passband selectivity and out-of-band rejection. These filters feature dynamic stopband characteristics by tuning the position of their transmission zeros. The operating principle, theoretical analysis, and design guidelines of the AWLR module, as well as a comparison with traditional all-AW ladder-type filters, are also reported. An original and rather simple $RLC$ -circuit equivalent of AW resonators that facilitates the incorporation of spurious modes into a simple Butterworth–Van-Dyke model for a more accurate synthesis of AWLR-based filters is extracted from measured two-port S-parameters.

In this paper, a new printed filtering antenna with selectivity enhancement is presented. Based on the co-design approach, the printed meander-line antenna and a quarter-wavelength resonator are used and integrated to be the filtering antenna. Here, an antenna performs not only a radiator but also the last resonator of the bandpass filter. A new structure of the quarter-wavelength resonator is also proposed, which can provide a shunt resonator with high capacitance and introduce two extra transmission zeros for selectivity enhancement. According to the filter specifications, a design procedure is depicted in detail. One example of a 2.45 GHz two-pole filtering antenna is described based on the second-order Chebyshev bandpass filter with 0.1 dB equal-ripple response. Furthermore, the proposed structure supply good filter skirt selectivity. The measured results, including the return loss and antenna gain versus frequency, have good agreement with the designed one.

This paper introduces folded DGS resonators to be used as building blocks of two-band band-pass filter. The transmission line with defected ground structure (DGS) can increase the equivalent capacitance and inductance of the transmission line and the dielectric constant. This character is useful for the design of miniaturization filter. The folded DGS resonator is then applied to design a multilayer second-order coupled resonator band-pass filter and a second-order two-band band-pass filter. The simulation results are presented to show the performance of these filters. It is easy to change the work frequency by adjusting the length of folded line and the thickness of resonator. External Quality Factor is connected with the length of feed line. It is significant for the research of the multi-frequency DGS filter.

In this paper, a highly dynamic filter cascade is presented with the capability of creating very high isolation regions in close spectral proximity to the received signal of interest. The cascade consists of 10 widely tunable resonators that can be combined to form advanced filtering functions. Two of the resonators are tasked to create a second-order Butterworth bandpass filter, while the other eight are used in a bandstop configuration to manipulate the stopband and form either very deep isolation, wide band isolation, or multiple isolation regions. This device consists of substrate-integrated, evanescent-mode cavities that are created using traditional circuit board technology as an example. 120 dB of isolation over a bandwidth of 21 MHz is achieved 16% away from the passband of the bandpass filter.

This paper presents the modeling and optimization of compact microwave bandpass filters whose compactness leads to complex and strong stray coupling paths, thereby making the identification of a simple and sparse coupling topology difficult and even impossible. The strong coupling coefficients needed for a broadband response can also cause an ambiguity in identifying the spatial extent of local resonances. An equivalent circuit, which is extracted directly from Maxwell's equations, is used in optimizing these filters. The filter is represented by its global resonances instead of individual resonators. The extraction of the parameters of the equivalent circuit is carried out in the physical frequency and not in the normalized frequency in order to preserve the physicality of the equivalent circuit, especially for asymmetric responses. The technique is successfully applied to the optimization of second-order suspended stripline bandpass filters with one transmission zero either below or above the passband, as well as fourth-order filters with three transmission zeros. A fourth-order filter with three transmission zeros is fabricated and measured.

A current mode second-order allpass notch and bandpass filter using a single CCII, two grounded capacitors and four resistors is proposed. The allpass and notch output current signals, taken out through port z of a CCII and having high output impedance, can be obtained by tuning a resistor in the proposed network. The resonance angular frequency and quality factor of the new network have the advantages of low passive sensitivities and are insensitive to the current tracking error of the nonideal CCII.