Timed array antenna system : application to wideband and ultra-wideband beamforming receivers

Antenna array systems have a broad range of applications in radio frequency (RF) and ultra-wideband (UWB) communications to receive/transmit electromagnetic waves from/to the sky. They can enhance the amplitude of the input signals, steer beams electronically, and reject interferences thanks to beamforming technique. In an antenna array beamforming system, delay cells with the tunable capability of delay amount compensate the relative delay of signals received by antennas. In fact, each antenna almost acts individually depending upon time delaying effects on the input signals. As a result, the delay cells are the basic elements of the beamforming systems. For this purpose, novel active true time delay (TTD) cells suitable for RF antenna arrays have been presented in this thesis. These active delay cells are based on 1st- and 2nd-order all-pass filters (APFs) and achieve quite a flat gain and delay within up to 10-GHz frequency range. Various techniques such as phase linearity and delay tunability have been accomplished to improve the design and performance. The 1st-order APF has been designed for a frequency range of 5 GHz, showing desirable frequency responses and linearity which is comparable with the state-of-the-art. This 1st-order APF is able to convert into a 2nd-order APF via adding a grounded capacitor. A compact 2nd-order APF using an active inductor has been also designed and simulated for frequencies up to 10 GHz. The active inductor has been utilized to tune the amount of delay and to reduce the on-chip size of the filter. In order to validate the performance of the delay cells, two UWB four-channel timed array beamforming receivers realized by the active TTD cells have been proposed. Each antenna channel exploits digitally controllable gain and delay on the input signal and demonstrates desirable gain and delay resolutions. The beamforming receivers have been designed for different UWB applications depending on their operating frequency ranges (that is, 3-5 and 3.1-10.6 GHz), and thus they have different system requirements and specifications. All the circuits and topologies presented in this dissertation have been designed in standard 180-nm CMOS technologies, featuring a unity gain frequency ( ft) up to 60 GHz.Els sistemes matricials d’antenes tenen una àmplia gamma d’aplicacions en radiofreqüència (RF) i comunicacions de banda ultraampla (UWB) per rebre i transmetre ones electromagnètics. Poden millorar l’amplitud dels senyals d’entrada rebuts, dirigir els feixos electrònicament i rebutjar les interferències gràcies a la tècnica de formació de feixos (beamforming). En un sistema beamforming de matriu d’antenes, les cèl·lules de retard amb capacitat ajustable del retard, compensen aquest retard relatiu dels senyals rebuts per les diferents antenes. De fet, cada antena gairebé actua individualment depenent dels efectes de retard de temps sobre el senyals d’entrada. Com a resultat, les cel·les de retard són els elements bàsics en el disseny dels actuals sistemes beamforming. Amb aquest propòsit, en aquesta tesi es presenten noves cèl·lules actives de retard en temps real (TTD, true time delay) adequades per a matrius d’antenes de RF. Aquestes cèl·lules de retard actives es basen en cèl·lules de primer i segon ordre passa-tot (APF), i aconsegueixen un guany i un retard força plans, en el rang de freqüència de fins a 10 GHz. Diverses tècniques com ara la linealitat de fase i la sintonització del retard s’han aconseguit per millorar el disseny i el rendiment. La cèl·lula APF de primer ordre s’ha dissenyat per a un rang de freqüències de fins a 5 GHz, mostrant unes respostes freqüencials i linealitat que són comparables amb l’estat de l’art actual. Aquestes cèl·lules APF de primer ordre es poden convertir en un APF de segon ordre afegint un condensador més connectat a massa. També s’ha dissenyat un APF compacte de segon ordre que utilitza una emulació d’inductor actiu per a freqüències de treball de fins a 10 GHz. S’ha utilitzat l'inductor actiu per ajustar la quantitat de retard introduït i reduir les dimensions del filtre al xip. Per validar les prestacions de les cel·les de retard propostes, s’han proposat dos receptors beamforming basats en matrius d’antenes de 4 canals, realitzats por cèl·lules TTD actives. Cada canal d’antena aprofita el guany i el retard controlables digitalment aplicats al senyal d’entrada, i demostra resolucions de guany i retard desitjables. Els receptors beamforming s’han dissenyat per a diferents aplicacions UWB segons els seus rangs de freqüències de funcionament (en aquest cas, 3-5 i 3,1-10,6 GHz) i, per tant, tenen diferents requisits i especificacions de disseny del sistema. Tots els circuits i topologies presentats en aquesta tesi s’han dissenyat en tecnologies CMOS estàndards de 180 nm, amb una freqüència de guany unitari (ft) de fins a 60 GHz.Postprint (published version

A 250-ps integrated ultra-wideband timed array beamforming receiver in 0.18 um CMOS

This paper presents a 4-channel ultra-wideband (UWB) timed array beamforming receiver designed in a standard 0.18-um CMOS technology. The proposed timed array receiver achieves a maximum delay of 250 ps at the maximum beam steering angle of +/-42o with 10.5o (8 steps) steering resolution and 2-cm antenna spacing. Each receiver channel provides gains ranging from 3.6 to -35 dB and less than 8% delay variation for all delay settings over a 3.1-10.6-GHz frequency range, while consuming a maximum of 58 mW power from a 1.8-V supply. The average -1-dB compression point P1dB is -9.9 dBm. The proposed architecture is modeled and simulated by using Virtuoso Cadence.This work has been partially supported by the Spanish Ministerio de Ciencia, Innovacion y Universidades (MICINN)- ´ Agencia Estatal de Investigacion (AEI) and the European ´ Regional Development Funds (FEDER), by project PGC2018- 098946-B-I00.Peer ReviewedPostprint (author's final draft

5GHz CMOS all-pass filter-based true time delay cell

Analog CMOS time-delay cells realized by passive components, e.g., lumped LC delay lines, are inefficient in terms of area for multi-GHz frequencies. All-pass filters considered as active circuits can, therefore, be the best candidates to approximate time delays. This paper proposes a broadband first-order voltage-mode all-pass filter as a true-time-delay cell. The proposed true-time-delay cell is capable of tuning delay, demonstrating its potential capability to be used in different systems, e.g., RF beam-formers. The proposed filter achieves a flat group delay of over 60 ps with a pole/zero pair located at 5 GHz. This proposed circuit consumes only 10 mW power from a 1.8-V supply. To demonstrate the performance of the proposed all-pass filter, simulation results are conducted by using Virtuoso Cadence in a standard TSMC 180-nm CMOS process.Postprint (published version

A 3–5-GHz, 385–540-ps CMOS true time delay element for ultra-wideband antenna arrays

© 2022 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper proposes an all-pass filter-based true time delay (TTD) element covering a 3–5-GHz ultra-wideband (UWB) frequency. The proposed TTD element designed in a standard 0.18-µm CMOS technology achieves a tunable delay range of 385–540 ps with 6-ps delay steps and maximum 11% absolute delay error over a 3–5-GHz frequency band. It exhibits an average 3.6–4.6-dB noise figure (NF) within the whole bandwidth. A four-channel beamforming receiver realized by the proposed TTD element is designed and examined in this paper, as well. With the maximum delay of 540 ps and 6-ps average delay resolution, a maximum steering angle of ±45¿ with 5¿ (18 steps) steering resolution is demonstrated for the beamforming receiver with 2-cm antenna spacing.Peer ReviewedPostprint (author's final draft