Talal Al-Attar

Millimeter-Wave and Terahertz Wireless RFIC and On-Chip Antenna Design: Tools and Layout Techniques

This invited contribution provides insights for im- plementation of millimeter-wave and terahertz wireless systems on a chip (MTWSOC). We present an overview of important software and simulation tools and key layout issues and design rules for millimeter-wave (mmWave) circuits. An example of a recently fabricated 0.18µm CMOS integrated circuit by the Wireless Networking and Communications Group (WNCG) at The University of Texas at Austin is presented. The example chip includes 60 GHz on-chip antennas, an array of transmission lines, and IMPATT diodes. Index Terms—60 GHz, millimeter-wave, on-chip antenna, IM- PATT diode, CPW, Transmission Lines, RFIC, CMOS, WPAN, SOC, MTWS

CMOS diodes operating beyond avalanche frequency

This paper describes IMPATT diodes designed and fabricated in 0.25µm CMOS technology to operate beyond avalanche frequency. IMPATT Impedance measurements from 40MHz to 110GHz confirmed avalanche frequency range from 30GHz to 55GHz and negative resistance tuning range from 30GHz to 80GHz. G&H model is verified and the impact of different device parameters are presented

Evaluating the robustness of tunable adaptive antenna arrays

We present an evaluation of tunable adaptive antenna array performance for achieving useful field patterns. Utilizing antenna elements which can be tuned by a controllable impedance “black box”, we characterize the arrays ability to achieve robust patterns for both broadcast and unicast communications. Simulation results demonstrate the impact of these tunable elements and the use of IMPATT diodes is introduced as a means to enable the tunable adaptive antenna array.

A physical model for tunable patch antennas

A model for tuning microstrip patch antennas with a controllable impedance “black box” is presented. These tunable impedance elements can be placed along the mid-line of the patch antenna to alter the impact of the tuning range on the antenna field pattern. Simulation results demonstrate the impact of this level of physical design control. Also highlighted is the improved ability to design beyond tunability with additional impedance matching and antenna area margins. Finally, the unique capability of the IMPATT diode for achieving these tunable impedance properties is discussed.

A novel technique to measure the input impedance of on-chip microstrip patch antenna in standard CMOS technology

This paper describes a novel technique to measure the input impedance of on-chip microstrip patch antenna in standard CMOS technology. By using the measured impedance of IMPATT diodes fabricated in the same standard CMOS technology and three lateral IMPATT diodes integrated with a microstrip patch antenna at one of the radiating edges, oscillation can be achieved and accurate measurement of the antenna input impedance can be extracted. The antenna used is 1.4mm2 and it is designed at 77GHz by using the high frequency electromagnetic field solver Sonnet. The detected oscillation observed in the range of 75∼77GHz, with transmitted power of −62dBm at 77GHz. The measured input impedance is within 10% of the simulated one. It is hoped that this technique will provide accurate method to measure the input impedance in the millimeter-wave range of on-chip antenna with minimum near-filed perturbation.

RWW 2017 Student Paper Contest

The purpose of the IEEE Radio & Wireless Week (RWW) Student Paper Contest is to reward students for exceptional work, taking into account both group as well as individual projects. The contest provides students with the opportunity to share their work and discuss their results with experts from industry and academia. It is open to all students attending RWW and presenting a paper at one of the topical conferences. Beginning in 2017, the Steering Committee established a new format for the Student Paper Contest, which is now a single event for the entire RWW.

CMOS IMPATT impedance and design parameters for millimetre-wave applications

This article describes lateral CMOS IMPATT diodes designed, monolithically integrated and fabricated in 0.18 µm CMOS technology. IMPATT diode impedance and avalanche frequency were confirmed in a measurement from 40 MHz to 110 GHz. Avalanche tuning range measured from 24 GHz to 44 GHz with maximum IMPATT negative resistance of 120 Ω at 38 GHz with 28 mA bias current. Furthermore, selection of the process technology and the impact of n-well impurity concentration are discussed. This device showed wide tuning range in the millimetre wave range and with the low cost of the CMOS technology used, these devices appear well suited for use in millimetre-wave applications.

Tunability of an area-efficient microstrip patch antenna at 60GHz

A method for shrinking a tunable microstrip patch antenna footprint is investigated. A reduced-area antenna at 60GHz is designed by taking advantage of the capacitive range of an IMPATT diode, being careful to maintain Q over a 2GHz bandwidth. To determine the capability of this tunable antenna system, the inductive extreme of the impedance tuning range is also evaluated for impact to resonance frequency. Further, results from the transmission line model used for analysis and design are confirmed using Sonnet Softwares professional EM solver.

A 0.18µm CMOS narrow-band LNA linearization using digital base-band post-distortion

In this paper, a novel digital base-band post-distorter is proposed to compensate for nonlinearities in low noise amplifiers. Though high gain, good input matching and low noise (low noise figure) are important factors, linearity and low power combined with these factors is most desirable. The proposed post-distorter achieves these factors by an indirect learning architecture at base-band to compensate for nonlinearities. The low noise amplifier was designed in the standard 0.18µm CMOS technology. It achieved a 8dB improvement in linearity with respect to the input power.