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- IEEE Transactions on Microwave Theory and Techniques
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The design of mixed-technology quasi-reflectionless planar bandpass filters (BPFs), bandstop filters (BSFs), and multi-band filters is reported. The proposed quasi-reflectionless filter architectures comprise a main filtering section that determines the power transmission response (bandpass, bandstop, or multi-band type) of the overall circuit network and auxiliary sections that absorb the reflected radio-frequency (RF) signal energy. By loading the input and output ports of the main filtering section with auxiliary filtering sections that exhibit a complementary transfer function with regard to the main one, a symmetric quasi-reflectionless behavior can be obtained at both accesses of the overall filter. The operating principles of the proposed filter concept are shown through synthesized first-order BPF and BSF designs. Selectivity-increase techniques are also described. They are based on: (i) cascading in-series multiple first-order stages and (ii) increasing the order of the filtering sections. Moreover, the RF design of quasi-reflectionless multi-band BPFs and BSFs is discussed. A hybrid integration scheme in which microstrip-type and lumped-elements are effectively combined within the filter volume is investigated for size miniaturization purposes. For experimental validation purposes, two quasi-reflectionless BPF prototypes (one- and two-stage architectures) centered at 2 GHz and a second-order BSF prototype centered at 1 GHz were designed, manufactured, andmore »
A coupling-matrix approach for the theoretical design of a type of input-reflectionless RF/microwave bandpass filters (BPFs) and bandstop filters (BSFs) is presented. They are based on diplexer architectures with arbitrary-order bandpass and bandstop filtering channels that feature complementary transfer functions. The transmission behavior of these reflectionless filters is defined by the channel that is not loaded at its output, whereas the input-signal energy that is not transmitted by this branch is completely dissipated by the loading resistor of the other channel. Analytical formulas for the coupling coefficients for the first-to-fourth-order filter designs are provided and validated through several synthesis examples. This theoretical design methodology, along with an optimization step, is also exploited to design input-quasi-reflectionless quasielliptic- type BPFs with a transmission-zero-(TZ)-generation cell in their bandpass filtering channel. In addition, the application of the proposed input-reflectionless BPF and BSF networks to input-quasi-reflectionless multiplexer design is approached. It is shown that a single resistively terminated multi-band BSF branch can absorb the input-signal energy not transmitted by the multiplexer channels in their common stopband regions to achieve quasi-reflectionless characteristics at its input. Moreover, experimental microstrip prototypes consisting of 2-GHz third-order BPF and BSF circuits, a 2-GHz sharp-rejection thirdorder BPF with two close-to-passband TZs,more »
This work is on the design, fabrication and characterization of a hexagonal ferrite band-pass filter that can be tuned either with a magnetic field or an electric field. The filter operation is based on a straight-edge Y-type hexagonal ferrite resonator symmetrically coupled to the input and output microstrip transmission lines. The Zn2Yfilter demonstrated magnetic field tunability in the 8–12 GHz frequency range by applying an in-plane bias magnetic field
H 0provided by a built-in permanent magnet. The insertion loss and 3 dB bandwidth within this band were 8.6 ± 0.4 dB and 350 ± 40 MHz, respectively. The electric field Etunability of the pass-band of the device was facilitated by the nonlinear magnetoelectric effect (NLME) in the ferrite. The E-tuning of the center frequency of the filter by (1150 ± 90) MHz was obtained for an input DC electric power of 200 mW. With efforts directed at a significant reduction in the insertion loss, the compact and power efficient magnetic and electric field tunable Zn2Y band-pass filter has the potential for use in novel reconfigurable RF/microwave devices and communication systems.
This paper reports on quasi-elliptic dual-band bandpass filters (BPFs) that were designed for the Filter Student Design Competition of the 2019 European Microwave Week. The proposed lumped-element (LE) BPF concept is based on two dual-band transversal cells and one multi-resonant cell that allow the realization of symmetric and asymmetric dual-band transfer functions shaped by six poles and five transmission zeros. A compact implementation scheme based on LE series resonators is proposed for size compactness and wide spurious free out-of-band response. For proof-of-concept demonstration purposes, a dual-band LE prototype with two passbands centered 1 and 1.5 GHz was designed, manufactured, and measured. It exhibited the following radio frequency measured performance characteristics. Passbands centered at 1.02 and 1.45 GHz, minimum insertion loss levels of 2.0 and 2.7 dB, and bandwidth of 146 and 105 MHz, respectively, for the first and the second passband, and out-of-band rejection >30 dB between 0 and 894 MHz, 1.17–1.34 GHz, and 1.72–6.9 GHz.
We present a low phase noise four-core triple-band voltage controlled-oscillator (VCO) with reconfigurable oscillator cores and multi-mode resonator. By activation/deactivation of oscillator cores and change of resonator impedance in three modes of operations, the proposed VCO provides complete freedom in selecting the resonance frequency for three operation bands in the mm-wave range. Compared to VCOs using switch-capacitor-bank for multi-band operation, the proposed VCO does not use any series switches with passive components in the resonator to provide a low phase noise in all three bands of operation. As a proof of concept, the proposed four-core triple-band VCO is implemented in a 65 nm CMOS process using four class-D oscillators with tail switches and a compact high-Q triple-mode resonator. The VCO oscillation frequencies center at 19, 28, and 38 GHz while providing good phase noise and low power consumption in all bands. Measured results show the total frequency tuning range (FTR) of 38.5% while the PN at 1MHz offset varies from -100.3 dBc/Hz to -106.06dBc/Hz resulting in an excellent FoMT of 199.8 dBc/Hz.