Dane Thompson

Characterization of liquid crystal polymer (LCP) material and transmission lines on LCP substrates from 30 to 110 GHz

Liquid crystal polymer (LCP) is a material that has gained attention as a potential high-performance microwave substrate and packaging material. This investigation uses several methods to determine the electrical properties of LCP for millimeter-wave frequencies. Microstrip ring resonators and cavity resonators are measured in order to characterize the dielectric constant (/spl epsi//sub r/) and loss tangent (tan/spl delta/) of LCP above 30 GHz. The measured dielectric constant is shown to be steady near 3.16, and the loss tangent stays below 0.0049. In addition, various transmission lines are fabricated on different LCP substrate thicknesses and the loss characteristics are given in decibels per centimeter from 2 to 110 GHz. Peak transmission-line losses at 110 GHz vary between 0.88-2.55 dB/cm, depending on the line type and geometry. These results show, for the first time, that LCP has excellent dielectric properties for applications extending through millimeter-wave frequencies.

Pattern and frequency reconfigurable annular slot antenna using PIN diodes

This paper presents the use of pin diodes to reconfigure the impedance match and modify the radiation pattern of an annular slot antenna (ASA). The planar antenna is fabricated on one side of a Duroid substrate and the microstrip feeding line with the matching network is fabricated on the opposite side of the board. The central frequency is 5.8 GHz and, by reconfiguring the matching circuit, the antenna was also designed to operate at 5.2 and 6.4 GHz. Pin diodes are also used to short the ASA in preselected positions along the circumference, thereby changing the direction of the null in the plane defined by the circular slot changes. As a proof of concept, two pin diodes are placed 45/spl deg/ on both sides of the feeding line along the ASA and the direction of the null is shown to align with the direction defined by the circular slot center and the diode. Consequently, a design that is reconfigurable in both frequency and radiation pattern is accomplished. Return loss and radiation pattern measurements and simulations are presented, which are in very good agreement.

3-D-integrated RF and millimeter-wave functions and modules using liquid crystal polymer (LCP) system-on-package technology

Electronics packaging evolution involves system, technology, and material considerations. In this paper, we present a novel three-dimensional (3-D) integration approach for system-on-package (SOP)-based solutions for wireless communication applications. This concept is proposed for the 3-D integration of RF and millimeter (mm) wave embedded functions in front-end modules by means of stacking substrates using liquid crystal polymer (LCP) multilayer and /spl mu/BGA technologies. Characterization and modeling of high-Q RF inductors using LCP is described. A single-input-single-output (SISO) dual-band filter operating at ISM 2.4-2.5 GHz and UNII 5.15-5.85 GHz frequency bands, two dual-polarization 2/spl times/1 antenna arrays operating at 14 and 35 GHz, and a WLAN IEEE 802.11a-compliant compact module (volume of 75/spl times/35/spl times/0.2 mm/sup 3/) have been fabricated on LCP substrate, showing the great potential of the SOP approach for 3-D-integrated RF and mm wave functions and modules.

Packaging of MMICs in multilayer LCP substrates

A 13-25-GHz GaAs bare die low noise amplifier is embedded inside a multilayer liquid crystal polymer (LCP) package made from seven layers of thin-film LCP. This new packaging topology has inherently unique properties that could make it an attractive alternative in some instances to traditional metal and ceramic hermetic packages. LCP is a near-hermetic material and its lamination process is at a relatively low temperature (285degC versus >800degC for ceramics). The active device is enclosed in a package consisting of several laminated C02 laser machined LCP superstrate layers. Measurements demonstrate that the LCP package and the 285degC packaging process have minimal effects on the monolithic microwave integrated circuit radio frequency (RF) performance. These findings show that both active and passive devices can be integrated together in a homogeneous laminated multilayer LCP package. This active/passive compatibility demonstrates a unique capability of LCP to form compact, vertically integrated (3-D) RF system-on-a-package modules

W-band characterization of finite ground coplanar transmission lines on liquid crystal polymer (LCP) substrates

Liquid Crystal Polymer (LCP) is a material with properties that suit it well as both a substrate and packaging material. LCPs multi-layer lamination capabilities, excellent electrical properties, and near hermetic nature suit it to a wide range of RF applications. Several frequency bands of interest. such as evolving applications in the 60 GHz band and military use at 94 GHz, could potentially benefit from the use of LCP system on package (SOP) devices. To test the viability of LCP at these frequencies, a conductor-hacked coplanar waveguide (CBCPW) on a 50 micron LCP substrate was fabricated and measured from 2 - 110 GHz. For measurement accuracy and substrate characterization, a through, reflect, line, (TRL) calibration was performed according to the National Institute of Standards and Technology (NIST) guidelimes. For the first time, LCP is characterized as a nun-wave circuit substrate up to 110 GHz.

A circularly polarized short backfire antenna excited by an unbalance-fed cross aperture

An unbalance-fed cross aperture is developed to excite a short backfire antenna (SBA) for circular polarization. The cross aperture consists of two orthogonal H-shaped slots with a pair of capacitive stubs and is fed by a single probe that forms an unbalanced feed with a shorting pin. It is demonstrated that the cross-aperture-excited SBA can achieve an axial ratio (les 3 dB) bandwidth of 4.2% with a voltage standing wave ratio (VSWR) bandwidth of 6.5% (VSWR<1.2) and a gain of 14 dBi. The antenna structure is described and the simulation and experimental results are presented. The mechanisms for impedance matching and circular-polarization production are analyzed

Development of a wide-band short backfire antenna excited by an unbalance-fed H-shaped slot

The short backfire antenna (SBA) has been widely used for mobile satellite communications, tracking, telemetry, and wireless local-area network applications due to its compact structure and excellent radiation characteristics. The most common excitation topology for the SBA is a balance-fed wire dipole, which has the disadvantage of a narrow frequency bandwidth for the input impedance. In this paper, an H-shaped slot is employed to excite the SBA for the first time. The H-shaped slot is unbalance-fed from a coaxial line. It is demonstrated that the H-shaped slot-excited SBA can achieve a bandwidth for input impedance of more than 20% (VSWR<2) while maintaining good radiation performance. The antenna structure is described and the simulation and experimental results are presented. The operating principle is investigated to explain why the slot-excited SBA can result in good impedance and radiation characteristics. A parametric study is conducted for the use of practical engineering design.

RF characteristics of thin film liquid crystal polymer (LCP) packages for RF MEMS and MMIC integration

A standard non-metallized liquid crystal polymer (LCP) 4 mil thick microwave substrate with depth-controlled laser-micromachined cavities was investigated as a system-level packaging layer for integrated packaging of monolithic microwave integrated circuits (MMICs) and radio frequency microelectromechanical systems (RF MEMS) switches. The RF characteristics of air/dielectric discontinuities at the cavity interfaces were first simulated and the results show that LCPs low dielectric constant enables cavity dimensions to be arbitrarily chosen without significantly affecting the RF performance. To test this packaging concept a 4 mil LCP sheet with twelve 1 mm /spl times/ 2.4 mm /spl times/ 2 mil deep cavities was fabricated. Air-bridge type RF MEMS switches were fabricated on a base LCP substrate and measured before and after introducing the laser-micromachined superstrate layer. The measurements show almost no difference in packaged and unpackaged form for frequencies up to 40 GHz. The concept of a system-level package on a flexible, low-cost, organic substrate has been demonstrated for the first time. The same technique could be used for integrating MMICs all in a near-hermetic low-cost LCP module.

Multi-band RF and mm-wave design solutions for integrated RF functions in liquid crystal polymer system-on-package technology

Electronic packaging evolution involves systems, technology and material considerations. In this paper, we present a liquid crystal polymer (LCP) based multilayer packaging technology that is rapidly emerging as an ideal platform for low cost, multi-band and reconfigurable RF front-end module integration. LCPs very low water absorption (0.04%), low cost and high electrical performance makes it very appealing for RF applications. Here we describe main characteristics and real performance of LCP substrate, by means of several design examples. A Single-Input-Single-Output (SISO) dual-band filter operating at ISM 2.4-2.5 GHz and UNII 5.15-5.85 GHz frequency bands, a dual polarization, dual frequency 2/spl times/1 antenna operating at 14 and 35 GHz, and a WLAN IEEE 802.11a compliant compact module (volume of 75/spl times/35/spl times/0.2 mm/sup 3/) have been fabricated on LCP substrate, showing the great potential of the System-On-Package approach for 3D compact, multi-band and reconfigurable integrated RF and millimeter waves functions and modules.

Development of mm-wave dual-frequency multilayer antenna arrays on liquid crystal polymer (LCP) substrate

The development of mm-wave dual frequency antenna arrays has been presented in multilayer LCP technology. Two 2times2 arrays operating at 14 and 35 GHz respectively have been designed and their impedance characteristics have been validated with measurements. These arrays can be integrated with 3D modules containing integrated circuits, filters and embedded passives to realize a complete system-on-package (SOP) based RF front end