Complete Characterization of Novel MHMICs for V-Band Communication Systems

Hindawi Publishing Corporation Journal of Electrical and Computer Engineering Volume 2013, Article ID 686708, 9 pages http://dx.doi.org/10.1155/2013/686708 Research Article Complete Characterization of Novel MHMICs for V-Band Communication Systems C. Hannachi,1 D. Hammou,1 T. Djerafi,1 Z. Ouardirhi,2 and S. O. Tatu1 1 Institut National de la Recherche Scientifique, Centre Énergie, Matériaux et Télécommunications, 800 de la Gauchetière Ouest, Montréal, QC, Canada H5A 1K6 2 Focus Microwaves, 1603 St. Regis, Dollard-des-Ormeaux, QC, Canada H9B 3H7 Correspondence should be addressed to C. Hannachi; Received 16 July 2013; Accepted 2 October 2013 Academic Editor: Alexander Koelpin Copyright © 2013 C. Hannachi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper presents the characterization results of several new passive millimeter wave circuits integrated on very thin ceramic substrate. The work is focused on the design and characterization of a novel rounded Wilkinson power divider, a 90∘ hybrid coupler, a rat-race coupler, and a novel six-port (multiport) circuit. Measurements show the wideband characteristics, allowing therefore their use for multi-Gb/s V-band wireless communication systems. 1. Introduction The use of the 60-GHz band has attracted a great deal of interest over the last few decades, especially for its use in future compact transceivers dedicated to high-speed wireless applications in indoor environments (57–64 GHz) [1–3]. In this context, intensive research has been done to further develop new millimeter wave components for high data rate wireless communications according to the IEEE 802.15.3c standard. As previously demonstrated, the six-port technology offers an excellent alternative to conventional receiver architectures, especially at millimeter wave frequencies [4–6]. Nowadays, there are few promising high-quality fabrication technologies, yielding potentially low-cost millimeter wave components, such as the monolithic microwave integrated Circuit (MMIC) on GaAs or SiGe for large-scale production, and the miniature hybrid microwave integrated circuit (MHMIC) technology on very thin ceramic substrates, for small-scale production and prototyping [7, 8]. Moreover, several technologies have been intensively used for the millimeter wave circuit design and in-house prototype fabrication. We particularly note the coplanar, the substrate integrated waveguide (SIW), and the microstrip technology. The coplanar technology assures high-quality component design but is not well suited for low-cost production due to the difficulties in automating wire-bonding implementation, necessary for obtaining repeatable performances. On the other hand, the SIW technology assures highquality component design on thin ceramics [9] or the design of optimal transitions from planar to standard rectangular waveguides [10]. For further circuit miniaturization, the microstrip technology on very thin, high relative permittivity substrate is recommended. As known, the microstrip line width is related to the characteristic impedance, substrate relative permittivity, and its thickness. It is to be noted that, due to reduced guided wavelength in high permittivity ceramic substrates, in order to keep the required circuit aspect ratio (guided wavelength versus the line width), the substrate must be as thin as possible. The optimal choice for frequencies greater than 60 GHz is the 127 𝜇m thick alumina substrate, which is also easily compatible with the usual 100 𝜇m thick MMIC active components, to be integrated with planar passive MHMICs. The MMIC chips are placed in rectangular cuts on ceramics, on the top of the same metallic fixture, allowing thermal dissipation and easy wire bonding with MHMIC components, which are practically at the same height. Initial designs and circuit characterization results of several MHMIC passive circuits on very thin ceramic substrate, designed for advanced millimeter wave systems operating in 60–90 GHz band, have been published few years ago [11]. 2 Journal of Electrical and Computer Engineering This paper presents novel circuit designs, together with major improvements obtained in fabrication and characterization process in recent years. Reflect Line Thru 2286 𝜇m 2. Calibration Techniques and Standards Measurement performance mainly depends on the accuracy of the calibration technique and its standards used for correcting the imperfections of the measurement system. These imperfections depend on several factors such as nonideal nature of cables and probes and the internal characteristics of the vector network analyzer (VNA) itself. In order to simplify calibration procedures and to obtain more accurate and reliable measurement by introducing much smaller systematic errors, the on-wafer calibration and measurement with picoprobes were adopted. Typically, on-wafer calibration standards are fabricated either on the wafer including the device under test (DUT) or on a separate impedance standard substrate (ISS). The reference plane is usually taken at the probe tips. Nevertheless, for the DUT measurement in microstrip technology, onwafer standards fabricated on the same wafer as the DUT are required since the probe-to-standard transition can be designed to be very similar to the transition to the DUT. It sometimes happens that the transition between the probe tips and the coplanar line end is not well matched and parasitic and some wave modes occur at the contact of the probe tips. By taking the probe tips as measurement reference plane, the errors due to this transition are not corrected and may affect the measurement results. Different calibration procedures or standards have been used for measuring microstrip-based circuits; among the most commonly used are line-reflect-match (LRM), lineline-reflect-match (LLRM), and thru-reflect-line (TRL) [12]. One of the most robust and popular technique is the TRL calibration, which is well suited to the on-wafer measurements at millimeter wave frequencies. According to previous comments, the reference plane is considered at the middle of the thru line. The TRL calibration was done using on-wafer microstrip structures and the TRL algorithm supported by our vector network analyzer E8362B of Agilent Technologies. A nonzero length thru is used to extend the reference plane a physical distance of 2286 𝜇m into the microstrip line in order to ensure direct measurement at the desired reference plane of the device, eliminating further deembedding and its associated uncertainties. One microstrip delay line of 477 𝜇m length is used to cover the whole considered frequency band. Generally, in order to avoid phase uncertainties, for TRL calibration, the electrical length of the line standard is maximum 180∘ at the highest operating frequency. (...truncated)