A Novel Chip to PCB-Half-Embedded Waveguide Transition

This paper presents electromagnetic band gap (EBG)-based periodic microstrip lines and balanced (differential) microstrip lines. Specifically, it is shown that through a proper modulation of the strip width in a microstrip transmission line, a stopband with controllable characteristics can be obtained. These EBG structures are then applied to differential microstrip lines, where it is shown that it is possible to achieve common-mode rejection in a certain frequency band, keeping the differential signals unaltered in that band. This is an interesting approach to implement common-mode suppressed differential microstrip lines without ground plane etching.

It is expected that the superior high‐frequency characteristics, such as low loss and low dispersion, of superconducting oxides are applied to microwave circuits. However, low‐loss superconducting oxide films can only be fabricated on limited types of substrate materials using present technologies. Therefore, the dielectric constant, dielectric loss, and thickness of substrate materials place severe limitations on the circuit design and the propagation characteristics.This paper discusses the attenuation constants, characteristic impedances, and wiring density of three fundamental planar transmission lines, namely, stripline, microstrip line, and coplanar waveguide fabricated on substrate materials MgO and LaAlO3. This discussion is based on the TEM and quasi‐TEM analysis procedures. The thin films with low surface resistances have been fabricated on MgO and LaAlO3. It is concluded that the microstrip line is suitable for fabricating a low‐loss transmission line and the coplanar waveguide on a low dielectric constant substrate is suitable for high‐density wirings.Also measured were the characteristics of the half‐wave transmission line resonators of these three transmission line configurations, which are made of EuBa2Cu3Ox thin films on an MgO substrate. The attenuation constant of 50 Ω, 50‐μm wide coplanar waveguide is 9.7 × 10−3 Np/m (8.4 × 10−2 dB/m) at 3.9 GHz and 28 K. This value is two orders of magnitude lower than that of the copper transmission line.

In this letter, a right-angle full Ka-band differential microstrip line (DML) to rectangular waveguide transition is proposed. A novel coupling probe configuration, which is considered to be a combination of a strip loop and a slot loop, is developed to improve the bandwidth of the transition. The 15 dB fractional bandwidth is increased from 33 to 40.6% compared with the right-angle DML-to-waveguide transition using multilayer PCB structure. To verify this transition, a back-to-back prototype is fabricated and measured. It provides an insertion loss of less than 1.2 dB and a return loss of better than 15 dB within a wide frequency range from 26.5 to 40 GHz. The measurement results show good agreements with the simulation ones.

Novel resistor-free differential microstrip lines prototype loaded with lossy metamaterial is proposed to achieve wideband common-mode (CM) absorption. The metamaterial is constructed by a chain of lossy complementary split-ring resonators (CSRRs), which are etched on the ground plane. Different from the CM absorption realized by lumped resistors, this work utilizes the inherent dielectric and conductor losses introduced by the differential microstrip lines and CSRRs to absorb CM energy. Furthermore, CSRRs are designed with gradual perturbation to broaden the CM absorption band. The lossy even-mode equivalent circuit models are established and analyzed to reveal the CM absorption mechanism. In order to verify the proposed strategy to design resistor-free differential microstrip lines with CM absorption, a sample was fabricated and measured. The measured <inline-formula> <tex-math notation="LaTeX">$S_{\mathrm {cc21}}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$S_{\mathrm {cc11}}$ </tex-math></inline-formula> are kept below &#x2212;10 dB simultaneously from 4.3 to 5.65 GHz with 27.4&#x0025; fractional bandwidth, where the CM energy is absorbed over 80&#x0025; by the dielectric and conductor losses. Meanwhile, the low insertion loss of <inline-formula> <tex-math notation="LaTeX">$S_{\mathrm {dd21}}$ </tex-math></inline-formula> below 6 GHz as well as the good differential-mode eye diagrams demonstrates that good signal integrity of differential signals is kept.

The introduction of electro-optic sampling techniques now allows the study of very high speed pulse propagation on planar transmission lines. In the frequency domain, recent work on microstrip and coplanar waveguides (CPW) on semiconductor substrates has shown the existence of slow-wave phenomena [1][2]. Since these phenomena are frequency dependent, strong dispersive effects on picosecond pulses would be expected. For a lossless substrate, a spectral domain technique has been used to calculate pulse dispersion for a coplanar waveguide (CPW) and coplanar strips [3], and for a particular geometry and lossy layer both mode matching and finite element techniques have been used to predict pulse behavior in microstrip and CPW [4]. In a typical structure exhibiting strong slow wave effects there are three distinct layers in the substrate: first, a thin, lossless spacer layer immediately below the CPW; second, a somewhat thicker lossy (i.e. doped) layer; and third, a very thick lossless layer. The slow-wave phenomenon (and corresponding variation in effective dielectric constant) occurs as a result of the different interactions of the electric and magnetic fields of the propagating wave with the lossy layer below the CPW. The complex effective dielectric constant of the guide is a function of the conductivity of the lossy layer, the separation of the CPW from this layer, the transmission line dimensions, and the frequency. For frequency domain applications, we have recently proposed a new method to control the slow wave factor in these structures by replacing the doped lossy layer with an (CW) optically generating electron-hole plasma layer in the semiconductor substrate [5]. The device could then serve as a phase-shifter, controlled by varying the optical excitation level, and thus the conductivity of the lossy layer. In this paper we discuss the the effects of the lossy layer on picosecond pulse dispersion.

The voltage standing wave on a coplanar waveguide (CPW) is measured at W-band (75–110 GHz) using an array of bismuth microbolometers placed over the CPW. From this information, the impedance at the end of the line can be determined in addition to the complex propagation constant of the CPW. This measurement technique should also be applicable for other planar transmission lines and be extendable above 110 GHz. This work represents the highest frequency, direct measurement of a VSW on a CPW made to date.

In this article, a novel method to suppress differential-to-common mode conversion noise in differential serpentine delay microstrip lines (DSDMLs) is proposed. To suppress the remnant mode conversion noise, embedded coupled lines are adopted in the parallel traces section of DSDMLs. Embedded coupled lines can minimize the timing delay between even- and odd-modes in the parallel traces section. In specific dimensions, embedded coupled lines propagate even- and odd-mode signals with the same velocity without changing the differential-mode impedance, so DSDMLs with embedded coupled lines can suppress differential-to-common mode conversion noise without degrading differential-mode signal quality. In simulations, the proposed DSDMLs exhibit about 93.0% suppression of the peak common-mode conversion voltage compared with conventional DSDMLs, regardless of the length of the parallel traces section of DSDMLs. The performance of our proposed DSDMLs is verified by conducting measurements with millimeter-scale test boards in the frequency and time domains. The test board exhibited 78.7% suppression of common-mode conversion noise without degrading the differential insertion loss compared with conventional DSDMLs. Simulations and measurement results exhibited good agreement.

In this paper, design and implementation of a 4.25Gb/s optical fiber transceiver for Gigabit Ethernet (GbE) applications based on IEEE802.3z standard using Multi Mode Fiber (MMF) is described. Transmitter consists of an 850 nm Vertical-Cavity Surface-Emitting Laser (VCSEL), laser driver and transmission lines and receiver consists of a PIN photodiode, amplifiers and transmission lines. Differential microstrip lines and single-ended Conductor Backed Coplanar Waveguides (CBCPWs) on a FR-4 Printed Circuit Board (PCB) are implemented. To evaluate the performance of the implemented optical transceiver, as the results, the measured eye diagrams and Bit Error Rate (BER) measurements at the transmitter and receiver outputs are presented.

In this letter, a comparative analysis is carried out between the mechanism of mode conversion in differential microstrip lines due to bend discontinuities on one side and trace asymmetry on the other side. With the help of equivalent modal circuits, a theoretical basis is provided for the idea to compensate the undesired common mode (CM), due to the presence of the bend, by intentionally designing asymmetric traces. As an application example, the proposed CM-reduction strategy is used in conjunction with another recently-presented wideband CM suppression filter for differential microstrip lines. It is shown that the proposed solution enhances the overall CM-reduction performance of the filter by some decibels, while preserving its transmission properties.

We investigated the propagation losses and the characteristic impedances Z/sub L/ of coplanar waveguides (CPWs) and microstrip lines (MSLs) on a planar lightwave circuit (PLC)-platform formed on a silica/silicon substrate. The loss of the CPWs was 2.7 dB/cm at 10 GHz on the PLC-platform with 30 /spl mu/m thick silica layer. Thus, a cm-order circuit of this CPW is difficult to fabricate in the 10 Gb/s module. This is because the silicon substrate has a large loss tangent (tan /spl delta/). On the other hand, the loss of the MSLs, where a ground plane shielded the high loss silicon substrate, could be improved to 0.9 dB/cm at 10 GHz with 30 /spl mu/m thick polyimide. These lower loss MSLs on a PLC-platform can be applied to module operation at 10 Gb/s. Furthermore they have the advantage that they are suitable for application to array device circuits or circuits in a module where several devices are integrated because unlike CPWs the ground planes are not divided by signal lines or DC bias lines. The structure of CPWs and MSLs on a PLC-platform with a Z/sub L/ of 50 /spl Omega/ was also studied in detail.

In this article, a novel procedure for the frequency-domain solution of nonuniform transmission lines (NUTLs) is presented. The procedure is based on a recently proposed perturbative technique, which is proven to be computationally more efficient than standard solution approaches, which are based on line subdivision into uniform cascaded sections. With respect to the original perturbation technique, the procedure proposed here offers more flexibility, as it provides a representation of the NUTL under analysis in terms of S and/or T parameters at its ports. Moreover, it retains the same prediction accuracy at the price of a slight increase in computational burden, which can be mitigated anyway through parallel computing. Furthermore, even without ad hoc (parallel) implementations, the proposed procedure outperforms other approaches to solve differential lines with partially or fully repetitive geometries. Namely, it assures accurate prediction of output quantities with reduced simulation time. This is proven by three application examples, namely, two differential trapezoidal tabbed lines (one with interdigital tabs and one with facing tabs), and a differential microstrip line with a varying common-mode (CM) impedance (as such reducing CM noise). Comparison with full-wave simulations allows assessing the prediction accuracy of the proposed procedure. Comparison with the aforementioned transmission-line-based solutions allows appreciating the enhanced computational efficiency.

This paper newly proposes that coupling between a coplanar waveguide (CPW) and a TE/sub 01/spl gamma//mode dielectric resonator (DR) can be realized for a parallel resonant characteristic as the DR coupled with a microstrip line. Coupling characteristics have been investigated by placing the DR on a special support above the CPW and by moving the DR away from the center of a slot of the CPW to the ground plane. FEM simulation (HFSS) results in terms of S-parameters agree well with measurement results. Finally, loaded Q values of the DR coupled with a CPW are compared with those of the DR coupled with a microstrip line. The comparison demonstrates that a DR coupled with a CPW has slightly higher loaded Q than that coupled with a microstrip line has.

A recently proposed multilayer concept for low loss RF-/DC-line crossings is extended to the case of multiple millimeter wave crossovers. DC-lines are realized as coplanar waveguides (CPW) in the common ground plane of RF microstrip lines (MSL). In comparison to undefected MSL transmission loss on the RF lines can be minimized by implementing suitable filters in the CPW. After a brief review of single crossings a systematic design of complex, multiple crossovers is presented. W-Band S-parameter measurements validate the approach.

A new miniature dual-band Wilkinson power divider (WPD) is presented in this paper. A technique made use of dual planar transmission lines was adopted in the design of this WPD. Namely, microstrip line (ML) and coplanar waveguide (CPW) line were used simultaneously on both the copper-sides of a substrate. Copper holes and vias were used to realize transitions between the dual lines. The miniature dual-band WPD was designed at 1 and 3 GHz with a physical area of $\pmb{9.1\times 5.4}\mathbf{mm}^{\pmb{2}}$ . The simulation results show that the insertion losses in both the 0.7-1.1 GHz and 2.7-3 GHz bands are less than 3.10 dB, the reflection coefficient are $ , and the isolation are better than 20 dB.

A new type of monolithic planar transmission line, the microshield line, is proposed. This line can operate without the need for via-holes or the use of air-bridges for ground equalization. Furthermore, it has shown the tendency to radiate less than the conventional microstrip or coplanar waveguide (CPW) and can provide a wide range of impedances due to the many available parameters for design. The space domain integral equation method is used to analyze four different discontinuities of the proposed type. A comparison to conventional CPW with respect to radiation shows very good performance. >