High-performance Passive Components Research Articles

Ultra wide-band, low Loss RF substrate with high-density DC routing supporting 5G/6G flip-chip RFICs

Abstract This paper presents the development of a substrate/interposer technology that is capable of supporting DC signal line routing down to <1mil trace and space densities, but also supports wideband, high-frequency and industry leading low loss RF routing from to beyond 175GHz. Building off of the proven performance and reliability of the PolyStrata® technology enabled air-coax routing, this paper discusses the development and addition of a redistribution technology that enables multilayer, high density DC signal routing at any point during the PolyStrata® process. This enhances the Polystrata® offering to a truly integrated substrate manufacturing process supporting high density interconnect requirement of flip-chip RF ICs as well as low loss high performance RF routing. The paper describes the design and fabrication of a demonstration part designed to accept a D-Band Flip-Chip RFIC. The chip side interconnects are 50um diameter copper pillar with solder cap, at 100um pitch with over 200 interconnects on a die. Multiple connections were required from 10Ghz to 175GHz as well has 30+ DC signal lines. The design can support this level of interconnect density and act as an interposer for next level interconnect to a printed circuit board. DC lines were routed out to a 400um pitch while RF interconnects can support transitions to micro-strip or strip-line PCB routing technology or waveguide, for easy and low loss interconnect to the next level system. An added benefit of being integrated into the PolyStrata® process is that high-performance passive components can be monolithically integrated into the interposer, and the demonstration vehicle implements a mmWave pass-band filter as well.

A comprehensive overview of recent developments in RF-MEMS technology-based high-performance passive components for applications in the 5G and future telecommunications scenarios

The goal of this work is to provide an overview about the current development of radio-frequency microelectromechanical systems technology, with special attention towards those passive components bearing significant application potential in the currently developing 5G paradigm. Due to the required capabilities of such communication standard in terms of high data rates, extended allocated spectrum, use of massive MIMO (Multiple- Input-Multiple-Output) systems, beam steering and beam forming, the focus will be on devices like switches, phase shifters, attenuators, filters, and their packaging/integration. For each of the previous topics, several valuable contributions appeared in the last decade, underlining the improvements produced in the state of the art and the chance for RFMEMS technology to play a prominent role in the actual implementation of the 5G infrastructure.

1 THz Micromachined Waveguide Band-Pass Filter

This paper presents a waveguide band-pass filter operating at the 0.75 ∼ 1.1 THz frequency band. The metal conductivity, the surface impedance, and the skin depth are investigated in the terahertz (THz) frequency band for more accurate designs, especially at the 1 THz and higher frequencies. Because the influence of the fabrication tolerance on the component performance cannot be negligible while the frequency increases, it is a necessary to adopt the simple structure with less resonant cavities for obtaining the given performance. Therefore, the filter in this paper is designed based on the TE301/TE102 dual-mode rectangular waveguide resonant cavities, which has fewer cavities and better rejection of the stop-band. The proposed filter is fabricated using the deep reactive ion etching (DRIE) micromachining technique. Measured results are in good agreement with simulations, which verifies the accuracy of the analysis above, and the design process is valuable to realize high-performance passive components while the frequency is up to 1 THz or higher frequencies.

A Multimetal Surface Micromachining Process for Tunable RF MEMS Passives

This paper reports on a microfabrication technology for implementing high-performance passive components suitable for advanced RF front-ends. This technology offers three metal layers with different thicknesses, one dielectric, and two sacrificial layers, enabling the fabrication of continuously tuned capacitors, capacitive and ohmic switches, as well as high- inductors all on a single chip. To demonstrate the versatility of this technology, several passive components are fabricated on a Borosilicate glass substrate . A high- tunable capacitor is fabricated exhibiting an electrostatic tuning range of more than 6 : 1. The temperature variation of capacitance from 223 to 333 K is less than 9%, and the tuning speed is better than 80 . To achieve a higher zero-bias capacitance, a tunable capacitor bank is also implemented, which can be tuned from 2.2 pF to 6.1 pF. In addition, a coupled inductor pair with self-inductances of 15 and 21 nH is implemented showing s exceeding 40 at 800 MHz. Measurements are compared with high frequency structure simulator (HFSS) electromagnetic simulations, showing good agreement. The technology reported is post-CMOS compatible and low cost.

Radio-frequency characterization for the single-walled carbon nanotubes

Carbon nanotube (CNT) has a potential to be used as nanoscale transmission lines and as high-performance passive components in nanoelectronics. In this letter, we discuss single-walled carbon nanotubes (SWNTs) that were grown using a chemical-vapor deposition technique. Both the dc and ac two-terminal resistances were measured and analyzed. The transmission properties of the SWNTs were shown by comparing the S parameters of a device with CNTs with those of a device without a CNT. The radio-frequency characterization of the CNTs was carried out using the network analyzer to frequency of 20GHz.

High-performance large-inductance embedded inductors in thin array plastic packaging (TAPP) for RF system-in-package applications

We report the first demonstration of high-Q embedded inductors fabricated using a thin-array-plastic-packaging (TAPP) technology. The TAPP technology provides a platform that integrates digital, analog, RF integrated circuits, along with high-performance passive components for system-in-package implementation. Embedded inductors ranging from 14 to 300 nH were fabricated. All the inductors with inductance less than 100 nH exhibit self-resonant frequency above 1 GHz. For a 14-nH inductor, Q factor of 35 was achieved at 1.6 GHz and the self-resonance frequency was measured at 6.15 GHz.