A new class of microwave dual-band bandpass planar filter is reported. It uses an original generalized branch-line hybrid topology devised here, operating as dual-passband transversal filtering section. This type of filter network, under feedforward signal-interaction concepts, enables dual-band bandpass filtering actions with transmission zeros to be generated. Some design formulas and guidelines helping to synthesize the proposed dual-passband transversal filtering section are given. Furthermore, to prove its practical viability, theoretical, simulated and experimental results of two manufactured sharp-rejection dual-band bandpass microstrip filter prototypes are shown.

Microwave Dual-Band Bandpass Planar Filters Based on Generalized Branch-Line Hybrids

In this paper, miniature branch-line coupler and Butler matrix designs for 2.5-GHz applications are proposed using the glass-based thin-film integrated passive device (TF-IPD) technology. The size reduction is achieved by replacing the quarter-wavelength transmission lines in a conventional branch-line coupler with the bridged-T coil. In this way, the circuit size can be largely reduced without sacrificing the operation bandwidth. The proposed miniature branch-line coupler is then applied to the design of a 4 × 4 Butler matrix centered at 2.5 GHz using the glass-based TF-IPD technology. The measured results show a bandwidth of 2.4-2.6 GHz for better than 13-dB return loss with a maximal dissipation of 4 dB, amplitude imbalance within 1.1 dB, and phase imbalance less than 13°. Notably, the proposed Butler matrix occupies a chip area of 3.13 mm × 3.3 mm, which is only about 0.026 λ0 × 0.027 λ0 at 2.5 GHz.

Miniature Butler Matrix Design Using Glass-Based Thin-Film Integrated Passive Device Technology for 2.5-GHz Applications

This paper presents a novel compact low-temperature cofired ceramic (LTCC) bandpass filter (BPF) with wide stopband and high selectivity. The proposed circuit consists of two coupled λg/4 transmission-line resonators. A special coupling region is selected to realize a novel discriminating coupling scheme for generating a transmission zero (TZ) at the third harmonic frequency. The mechanism is analyzed and the design guideline is described. The source-load coupling is introduced to generate two TZs near the passband and one in the stopband. Thus, wide stopband can be obtained without extra circuits. Due to the LTCC multilayer structures, the filter size is 0.058 λg×0.058 λg×0.011 λg, or 2.63 mm × 2.61 mm × 0.5 mm. The simulated and measured results of the demonstrated LTCC BPF are presented to validate the proposed design.

Compact LTCC Bandpass Filter With Wide Stopband Using Discriminating Coupling

Millimeter-wave (mmW) bandpass filters (BPFs) using substrate integrated waveguide (SIW) are proposed in this paper. The propagation constants of two different types of electromagnetic bandgap (EBG) units are discussed and compared for their passbands and stopbands performance. In among, the slotted-SIW unit shows a very good lower and upper-stopband performance. The mmW BPF with three cascaded uniform slotted-SIW-based EBG units is constructed and designed at 40-GHz. This EBG filter exhibits good out-of-band performance. To further improve the in-band performance, a third-order mmW BPF with nonuniformly cascaded slotted-SIW unit is designed at 140 GHz. The filter is investigated with the theory of electric coupling mechanism. The extracted coupling coefficient (K) and quality factor (Q) are used to determine the filter circuit dimensions. To prove the validity, the two proposed structures are fabricated in a single-circuit layer using low temperature co-fired ceramic technology and measured at 40 and 140 GHz, respectively. The measured results are in good agreement with the simulated results in such high frequency. The measured insertion losses at 40 GHz and 140 GHz are 0.72 and 1.913 dB, respectively.

Electric Coupling Structure of Substrate Integrated Waveguide (SIW) for the Application of 140-GHz Bandpass Filter on LTCC

A half-mode substrate integrated waveguide (HMSIW), based on printed circuit board (PCB) technology, is employed to construct a novel $V$ -band leaky-wave antenna incorporating composite right-/left-handed (CRLH) media. Including modified half-sinusoidally varied interdigital capacitive slots on the radiating edge of the HMSIW enables the feature of effective CRLH media to produce adequate radiation coverage and bandwidth with improved sidelobe level (SLL) and higher gain. Unit cell characteristics and space harmonic analysis were thoroughly investigated through dispersion and Bloch impedance analysis. By appropriately tuning the physical parameters of the design, the balanced condition was obtained at a broadside frequency of 60 GHz. The highly directed radiated fan beam covered a scanning range of 120° with beam steering from −72° to 48° of the visible space. The proposed antenna operated over 55–65 GHz with a maximum realized gain of 14.5 dBi, maximum beamwidth of 9.15°, better than 15 dB SLL and 20 dB cross-polar radiation. All simulated responses showed reasonably good accordance with experimental data thereby validating the novel design of the proposed leaky-wave structure for millimeter-wave wireless applications.

60 GHz Compact Larger Beam Scanning Range PCB Leaky-Wave Antenna Using HMSIW for Millimeter-Wave Applications

A 60 GHz reduced-size branch-line coupler has been developed using elevated-center coplanar waveguide (EC-CPW) transmission lines. The coupler is fabricated in a 90 nm CMOS technology and has a chip area of 0.102 mm2. The measurements indicated an amplitude-imbalance of 0.7 dB and a phase difference of 88 degrees at 60 GHz, a return loss of greater than 15 dB at every port over the 60 GHz band (57-64 GHz), and an isolation better than 17 dB. A 73% size-reduction compared to a conventional CPW coupler design has been achieved using capacitively loaded high-impedance EC-CPW lines. The proposed coupler is well suited for the design of millimeter-wave (mmW) CMOS subsystems including: balanced amplifiers, vector modulators, and balanced mixers.

Experimental Analysis of a 60 GHz Compact EC-CPW Branch-Line Coupler for mm-Wave CMOS Radios

A compact 60-GHz band branch-line coupler using cpacitively loaded lower-ground coplanar-waveguide (LG-CPW) lines has been successfully demonstrated in a glass-substrate integrated passive device technology. The fabricated coupler has a size reduction of more than 83% compared to that of a conventional CPW branch-line coupler. The capacitive loading is achieved by utilizing the signal layer and the LG of the LG-CPW structure to form microstrip open-circuited stubs. The measured results show a phase error of less than 0.5° between the coupler's output ports and an amplitude imbalance of less than 1.2 dB over the frequency band 57-64 GHz. The measurements also show that both the return loss and isolation are better than 25 dB at 60 GHz and better than 15 dB over the 57-64-GHz band. The proposed coupler is well suited for low-cost high-performance system-on-package V-band radio front ends for high data rate applications.

Compact 60-GHz IPD-Based Branch-Line Coupler for System-on-Package V-Band Radios

This paper presents a comparison of the design and implementation of V-band quasi-elliptic band pass filters suitable for system-on-package integration at millimetre-wave frequencies. Filters were designed and manufactured at low-temperature co-fired ceramic (LTCC) and alumina substrates. Filter circuits include the input/output coplanar waveguide to microstrip transitions as well as the microwave pads, used to facilitate measurement. Three four-pole filters incorporating half-wavelength resonators were implemented, two planar (on LTCC and alumina substrates) and one vertically stacked (on LTCC). In addition a six-pole filter was also implemented in alumina. The four-pole LTCC based filters have a measured insertion loss (IL) as low as 3.4 dB, fractional bandwidth (FBW(%) = BW-3 dB/Center Frequency) of 4.8% and return loss better than 10 dB. Total filter size is less than 1.1 × 0.74 mm. The alumina-based four-pole/six-pole filters exhibit a measured IL of 2.8/3.1 dB, FBW of 8.3%/12.6%, respectively. Both alumina filters exhibit a return loss better than 10 dB and with a corresponding filter layout footprint of less than 1.01 × 1.34 mm. A new figure-of-merit (HPFOM) is proposed and results from the filters proposed here clearly show they offer the best trade-off between performance and area (higher HPFOM).

High-Performance, Compact Quasi-Elliptic Band Pass Filters for V-Band High Data Rate Radios

A compact 24–26 GHz low loss 4×4 Butler matrix is implemented in an IPD (integrated passive device) technology and presented in this paper. A modified coplanar waveguide (M-CPW) branch line coupler is utilized as the core element of the Butler matrix. The proposed Butler matrix occupies a chip area of 2.2 × 1.9 mm2 (excluding the I/O test pads). The measured results showed output relative phase errors of less than 5% over a frequency range of 26–29 GHz and less than 13% over 24–25 GHz, and output amplitude imbalances of less than 1.3 dB over a frequency range of 24–27 GHz. The proposed Butler matrix is well suited for use in microwave low-cost, high performance beam forming wireless communications systems.

A compact 24–26 GHz IPD-based 4×4 Butler matrix for beam forming antenna systems

A V-band low-noise, high gain, high linearity single-stage amplifier has been developed in a 90-nm CMOS technology. The design utilized modified co-planar waveguide transmission lines for the input/output matching networks, to avoid lines' width and spacing constraints and to sustain small chip area and low cost fabrication. The developed amplifier exhibited a low noise figure of 4.1 dB, and a gain higher than 10 dB in the frequency range of 57–58 GHz. Additionally, the amplifier has linear characteristics and its measured third-order intercept (IIP3) point is greater than 3 dBm. The proposed design is well suited for millimeter-wave (mmW) front-ends in ultra-wideband (UWB) radio-over-fiber (RoF) systems for high data-rate communications.

Ibrahim Haroun

Papers

Experimental Analysis of a 60 GHz Compact EC-CPW Branch-Line Coupler for mm-Wave CMOS Radios

Compact 60-GHz IPD-Based Branch-Line Coupler for System-on-Package V-Band Radios

High-Performance, Compact Quasi-Elliptic Band Pass Filters for V-Band High Data Rate Radios

A compact 24–26 GHz IPD-based 4×4 Butler matrix for beam forming antenna systems

A V-band 90-nm CMOS low-noise amplifier with modified CPW transmission lines for UWB systems