The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Harish Krishnaswamy - One of the best experts on this subject based on the ideXlab platform.
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ultra compact ultra wideband dc 1ghz cmos Circulator based on quasi electrostatic wave propagation in commutated switched capacitor networks
Radio Frequency Integrated Circuits Symposium, 2020Co-Authors: Aravind Nagulu, Andrea Alu, Mykhailo Tymchenko, Harish KrishnaswamyAbstract:Recent research has revealed the possibility to achieve non-magnetic non-reciprocity using time-variance. However, prior CMOS-based Circulators rely on the interference between non-reciprocal switched-capacitor/transmission-line gyrators and reciprocal transmission-line rings, which increases form factor and restricts frequency tunability and bandwidth. On the other hand, recent works on quasi-electrostatic wave propagation in switched-capacitor media have demonstrated a new regime in multipath switched-capacitor network operation that enables an ultra-broadband, ultra-compact reciprocal/non-reciprocal true-time-delay element. In this work, we apply synthetic rotation across this quasi-electrostatic medium to realize an ultra-broadband N-port Circulator with ultra-compact form-factor. This new architecture is showcased in a wideband 3-port Circulator implemented in a standard 65nm CMOS process. This Circulator exhibits symmetric performance across all 3 ports and DC-1GHz operation for a modulation frequency of 500MHz. The measured transmission losses range between 3.1-4.3dB, matching is 18dB and NF is consistent with the insertion loss. This device occupies an area of 0.19mm2 ($\lambda _{center}^2/1.9 \times {10^6}$), representing about 100-1000× higher miniaturization compared to the prior art.
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a single antenna full duplex radio using a non magnetic cmos Circulator with in built isolation tuning
International Conference on Communications, 2019Co-Authors: Aravind Nagulu, Tingjun Chen, Gil Zussman, Harish KrishnaswamyAbstract:Wireless systems which can simultaneously transmit and receive (STAR) are gaining significant academic and commercial interest due to their wide range of applications such as full-duplex (FD) wireless communication and FMCW radar. FD radios, where the transmitter (TX) and the receiver (RX) operate simultaneously at the same frequency, can potentially double the data rate at the physical layer and can provide many other advantages in the higher layers. The antenna interface of an FD radio is typically built using a multi-antenna system, or a single antenna through a bulky magnetic Circulator or a lossy reciprocal hybrid. However, recent advances in CMOS-integrated Circulators through spatio-temporal conductivity modulation have shown promise and potential to replace traditional bulky magnetic Circulators. However, unlike magnetic Circulators, CMOS-integrated non-magnetic Circulators will introduce some nonlinear distortion and spurious tones arising from their clock circuitry. In this work, we present an FD radio using a highly linear CMOS integrable Circulator, a frequency-flat RF canceler, and a USRP software-defined radio (SDR). At TX power level of +15 dBm, the implemented FD radio achieves a self-interference cancellation (SIC) of +55 dB from the Circulator and RF canceler in the RF domain, and an overall SIC of +95 dB together with SIC in the digital domain. To analyze the non-linear phenomena of the CMOS Circulator, we calculated the link level data-rate gain in an FD system with imperfect SIC and then extended this calculation to count the effect of TX-RX non-linearity of the Circulator. In addition, we provide a qualitative discussion on the spurious tone responses of the Circulator due to the clocking imperfections and non-linearity.
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28 5 non magnetic 60ghz soi cmos Circulator based on loss dispersion engineered switched bandpass filters
International Solid-State Circuits Conference, 2019Co-Authors: Aravind Nagulu, Harish KrishnaswamyAbstract:There has been significant recent research on non-magnetic non-reciprocal components at RF and mm-waves, such as Circulators and isolators, based on spatio-temporal modulation [1-3]. Circulators enable simultaneous transmit and receive (STAR) on a shared antenna for applications such as full-duplex wireless communication and FMCW radar. While there has been exciting initial progress, existing architectures do not scale well to mm-waves, whether they are based on switch-based conductivity modulation [1, 2]or varactor-based permittivity modulation [3]. Loss levels increase due to losses in the switches or varactors, isolation is degraded due to reflections produced by parasitics, and power consumption is high due to the relatively high modulation frequencies required. In this work, we present a non-magnetic CMOS 60GHz Circulator based on spatiotemporal conductivity modulation (STCM) across a loss/dispersion-engineered bandpass filter. This new architecture improves the insertion loss, isolation, power consumption, and spurious response compared to prior art. The 60GHz Circulator achieves 3.6dB/3.1dB insertion loss for TX-to-ANT/ANT-to-RX paths, respectively, TX-to-RX isolation $> 40$dB over 1.3GHz, 3.2dB of ANT-to-RX NF, $> +19.5$dBm TX-to-ANT/ANT-to-RX IP 1dB S and spurious tones lower than -30dBc at both ANT and RX ports at a power consumption of 41mW from 1.2V.
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fully integrated non magnetic 180nm soi Circulator with 1w p1db 50dbm iip3 and high isolation across 1 85 vswr
Radio Frequency Integrated Circuits Symposium, 2018Co-Authors: Aravind Nagulu, Andrea Alu, Harish KrishnaswamyAbstract:There has been recent progress on CMOS non-magnetic Circulators based on switch-based spatio-temporal conductivity modulation, but these initial demonstrations remain limited in transmitter power handling, linearity, and ability to combat antenna variations. This paper describes a non-magnetic Circulator in 180nm SOI CMOS that uses no external components, and employs various linearity enhancement techniques such as device stacking, optimal switch biasing, and localized ESD design to achieve >1W TX-ANT PldB and >+50dBm TX-ANT IIP3 at 1GHz. A new loss-free and inductor-free antenna balancing approach enables high isolation for as high as 1.85 ANT VSWR and beyond. The Circulator also exhibits low insertion losses of 2.1dB/2.9dB in the TX-ANT and ANT-RX paths, and ANT-RX NF of 3.1dB. These results represent a 10–100×enhancement in linearity/power handling over prior CMOS non-reciprocal Circulators, and are shown to lower the power consumption of a communication link when compared with state-of-the-art electrical balance duplexers in scenarios where dynamic range is limited by P1dB, NF.
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a millimeter wave non magnetic passive soi cmos Circulator based on spatio temporal conductivity modulation
IEEE Journal of Solid-state Circuits, 2017Co-Authors: Tolga Dinc, Aravind Nagulu, Harish KrishnaswamyAbstract:Linear, time-invariant, passive circuits and systems constructed from conventional materials with symmetric permittivity and permeability tensors are reciprocal. Breaking Lorentz reciprocity enables the implementation of non-reciprocal components, such as gyrators, isolators, and Circulators, which find application in numerous wireless communication systems. Non-reciprocal components are traditionally implemented using ferrite materials, which exhibit the Faraday effect under the application of an external magnetic field bias. However, ferrite materials cannot be integrated into CMOS fabrication processes and require an external biasing magnet, and hence are bulky and expensive. Recently, there has been significant research interest in the implementation of non-magnetic non-reciprocal components using temporal modulation, including a fully integrated 25-GHz Circulator in a 45-nm SOI CMOS, demonstrating magnetic-free passive non-reciprocity on silicon at millimeter waves for the first time. This paper presents a detailed analysis of the millimeter-wave Circulator in both time and frequency domains. Millimeter-wave non-reciprocal operation is enabled by the concept of spatio-temporal conductivity modulation, which achieves broadband non-reciprocal gyrator functionality over theoretically infinite bandwidth (BW). When compared with prior approaches based on N-path filters, spatio-temporal conductivity modulation requires only four-phase 50% duty-cycle clocking at frequencies significantly lower than the operation frequency, enabling scaling to millimeter waves. The 25-GHz Circulator achieves minimum transmitter (TX)-to-antenna (ANT)/ANT-to-receiver (RX) insertion losses of 3.3 dB/3.2 dB, respectively, with a 1-dB BW of 4.6 GHz. TX-to-RX isolation is 18.3–21.2 dB (limited by the measurement setup) over the same BW. The Circulator IC occupies an area of 1.2 mm $\times $ 1.8 mm ( $\lambda /8 \times \lambda $ /6). The spatio-temporal conductivity modulation concept is readily scalable across frequency and can be an enabler for higher millimeter-wave (e.g., 77 GHz) Circulators as well as optical isolators.
Andrea Alu - One of the best experts on this subject based on the ideXlab platform.
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ultra compact ultra wideband dc 1ghz cmos Circulator based on quasi electrostatic wave propagation in commutated switched capacitor networks
Radio Frequency Integrated Circuits Symposium, 2020Co-Authors: Aravind Nagulu, Andrea Alu, Mykhailo Tymchenko, Harish KrishnaswamyAbstract:Recent research has revealed the possibility to achieve non-magnetic non-reciprocity using time-variance. However, prior CMOS-based Circulators rely on the interference between non-reciprocal switched-capacitor/transmission-line gyrators and reciprocal transmission-line rings, which increases form factor and restricts frequency tunability and bandwidth. On the other hand, recent works on quasi-electrostatic wave propagation in switched-capacitor media have demonstrated a new regime in multipath switched-capacitor network operation that enables an ultra-broadband, ultra-compact reciprocal/non-reciprocal true-time-delay element. In this work, we apply synthetic rotation across this quasi-electrostatic medium to realize an ultra-broadband N-port Circulator with ultra-compact form-factor. This new architecture is showcased in a wideband 3-port Circulator implemented in a standard 65nm CMOS process. This Circulator exhibits symmetric performance across all 3 ports and DC-1GHz operation for a modulation frequency of 500MHz. The measured transmission losses range between 3.1-4.3dB, matching is 18dB and NF is consistent with the insertion loss. This device occupies an area of 0.19mm2 ($\lambda _{center}^2/1.9 \times {10^6}$), representing about 100-1000× higher miniaturization compared to the prior art.
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radio frequency magnet free Circulators based on spatiotemporal modulation of surface acoustic wave filters
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Giuseppe Michetti, Ahmed Kord, Dimitrios L Sounas, Andrea Alu, Michele Pirro, Zhicheng Xiao, Cristian Cassella, Matteo RinaldiAbstract:In this article, a new generation of magnet-free Circulators with high performance is proposed. Circulators are crucial devices in modern communication systems due to their ability to enable full-duplexing and double the spectral efficiency directly in the physical layer of the radio-frequency (RF) front end. Traditionally, the Lorentz reciprocity is broken by applying the magnetic bias to ferrite materials; therefore, conventional Circulators are bulky and expensive. In this article, this problem is addressed by replacing the magnetic bias with periodic spatiotemporal modulation. Compared to previous works, the proposed Circulator is constructed using surface acoustic wave (SAW) filters instead of transmission lines (TLs), which reduces the modulation frequency by at least a factor of 20 and ensures ultra-low power consumption and high linearity. The miniaturized high quality ( ${Q}$ ) factor SAW filters also lead to a low-loss nonreciprocal band with strong isolation (IX) and broad bandwidth (BW) on a chip scale, therefore addressing such limitations in previous magnet-free demonstrations. Furthermore, compared to the conventional differential circuit configuration, a novel quad configuration is developed, which doubles the intermodulation-free BW.
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radio frequency magnet free Circulators based on spatiotemporal modulation of surface acoustic wave filters
arXiv: Signal Processing, 2019Co-Authors: Giuseppe Michetti, Ahmed Kord, Dimitrios L Sounas, Andrea Alu, Michele Pirro, Zhicheng Xiao, Cristian Cassella, Matteo RinaldiAbstract:In this paper, a new generation of magnet-free Circulators with high performance is proposed. Circulators are crucial devices in modern communication systems due to their ability to enable full-duplexing and double the spectral efficiency directly in the physical layer of the radio-frequency (RF) front-end. Traditionally, Lorentz reciprocity is broken by applying magnetic bias to ferrite materials, therefore conventional Circulators are bulky and expensive. In this paper, this problem is addressed by replacing the magnetic bias with periodic spatiotemporal modulation. Compared to previous works, the proposed Circulator is constructed using surface acoustic wave (SAW) filters instead of transmission lines (TL), which reduces the modulation frequency by at least a factor of 20 and ensures ultra-low power consumption and high linearity. The miniaturized high quality (Q) factor SAW filters also lead to a low-loss non-reciprocal band with strong isolation (IX) and broad bandwidth (BW) on a chip scale, therefore addressing such limitations in previous magnet-free demonstrations. Furthermore, compared to the conventional differential circuit configuration, a novel quad configuration is developed, which doubles the intermodulation-free bandwidth.
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Nonlinearity-based Circulator
Applied Physics Letters, 2019Co-Authors: Giuseppe D'aguanno, Dimitrios L Sounas, Hady M. Saied, Andrea AluAbstract:Commercially available nonreciprocal devices, such as isolators and Circulators, play a fundamental role in communication systems. Since they commonly rely on magnetic materials, they tend to become bulky, expensive, and difficult to be integrated in conventional microelectronic circuits. Here, we explore the functionality of a magnetic-free Circulator where reciprocity is broken by suitable geometric asymmetries combined with tailored nonlinearities. We show that it is possible to operate a fully passive coupled resonator system without external bias like a Circulator for pulsed signals impinging at its ports within a desired range of intensities. The functionality can be applied to a variety of physical systems, ranging from electronics to photonics and acoustics.
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fully integrated non magnetic 180nm soi Circulator with 1w p1db 50dbm iip3 and high isolation across 1 85 vswr
Radio Frequency Integrated Circuits Symposium, 2018Co-Authors: Aravind Nagulu, Andrea Alu, Harish KrishnaswamyAbstract:There has been recent progress on CMOS non-magnetic Circulators based on switch-based spatio-temporal conductivity modulation, but these initial demonstrations remain limited in transmitter power handling, linearity, and ability to combat antenna variations. This paper describes a non-magnetic Circulator in 180nm SOI CMOS that uses no external components, and employs various linearity enhancement techniques such as device stacking, optimal switch biasing, and localized ESD design to achieve >1W TX-ANT PldB and >+50dBm TX-ANT IIP3 at 1GHz. A new loss-free and inductor-free antenna balancing approach enables high isolation for as high as 1.85 ANT VSWR and beyond. The Circulator also exhibits low insertion losses of 2.1dB/2.9dB in the TX-ANT and ANT-RX paths, and ANT-RX NF of 3.1dB. These results represent a 10–100×enhancement in linearity/power handling over prior CMOS non-reciprocal Circulators, and are shown to lower the power consumption of a communication link when compared with state-of-the-art electrical balance duplexers in scenarios where dynamic range is limited by P1dB, NF.
Matteo Rinaldi - One of the best experts on this subject based on the ideXlab platform.
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radio frequency magnet free Circulators based on spatiotemporal modulation of surface acoustic wave filters
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Giuseppe Michetti, Ahmed Kord, Dimitrios L Sounas, Andrea Alu, Michele Pirro, Zhicheng Xiao, Cristian Cassella, Matteo RinaldiAbstract:In this article, a new generation of magnet-free Circulators with high performance is proposed. Circulators are crucial devices in modern communication systems due to their ability to enable full-duplexing and double the spectral efficiency directly in the physical layer of the radio-frequency (RF) front end. Traditionally, the Lorentz reciprocity is broken by applying the magnetic bias to ferrite materials; therefore, conventional Circulators are bulky and expensive. In this article, this problem is addressed by replacing the magnetic bias with periodic spatiotemporal modulation. Compared to previous works, the proposed Circulator is constructed using surface acoustic wave (SAW) filters instead of transmission lines (TLs), which reduces the modulation frequency by at least a factor of 20 and ensures ultra-low power consumption and high linearity. The miniaturized high quality ( ${Q}$ ) factor SAW filters also lead to a low-loss nonreciprocal band with strong isolation (IX) and broad bandwidth (BW) on a chip scale, therefore addressing such limitations in previous magnet-free demonstrations. Furthermore, compared to the conventional differential circuit configuration, a novel quad configuration is developed, which doubles the intermodulation-free BW.
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radio frequency magnet free Circulators based on spatiotemporal modulation of surface acoustic wave filters
arXiv: Signal Processing, 2019Co-Authors: Giuseppe Michetti, Ahmed Kord, Dimitrios L Sounas, Andrea Alu, Michele Pirro, Zhicheng Xiao, Cristian Cassella, Matteo RinaldiAbstract:In this paper, a new generation of magnet-free Circulators with high performance is proposed. Circulators are crucial devices in modern communication systems due to their ability to enable full-duplexing and double the spectral efficiency directly in the physical layer of the radio-frequency (RF) front-end. Traditionally, Lorentz reciprocity is broken by applying magnetic bias to ferrite materials, therefore conventional Circulators are bulky and expensive. In this paper, this problem is addressed by replacing the magnetic bias with periodic spatiotemporal modulation. Compared to previous works, the proposed Circulator is constructed using surface acoustic wave (SAW) filters instead of transmission lines (TL), which reduces the modulation frequency by at least a factor of 20 and ensures ultra-low power consumption and high linearity. The miniaturized high quality (Q) factor SAW filters also lead to a low-loss non-reciprocal band with strong isolation (IX) and broad bandwidth (BW) on a chip scale, therefore addressing such limitations in previous magnet-free demonstrations. Furthermore, compared to the conventional differential circuit configuration, a novel quad configuration is developed, which doubles the intermodulation-free bandwidth.
Dimitrios L Sounas - One of the best experts on this subject based on the ideXlab platform.
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radio frequency magnet free Circulators based on spatiotemporal modulation of surface acoustic wave filters
IEEE Transactions on Microwave Theory and Techniques, 2019Co-Authors: Giuseppe Michetti, Ahmed Kord, Dimitrios L Sounas, Andrea Alu, Michele Pirro, Zhicheng Xiao, Cristian Cassella, Matteo RinaldiAbstract:In this article, a new generation of magnet-free Circulators with high performance is proposed. Circulators are crucial devices in modern communication systems due to their ability to enable full-duplexing and double the spectral efficiency directly in the physical layer of the radio-frequency (RF) front end. Traditionally, the Lorentz reciprocity is broken by applying the magnetic bias to ferrite materials; therefore, conventional Circulators are bulky and expensive. In this article, this problem is addressed by replacing the magnetic bias with periodic spatiotemporal modulation. Compared to previous works, the proposed Circulator is constructed using surface acoustic wave (SAW) filters instead of transmission lines (TLs), which reduces the modulation frequency by at least a factor of 20 and ensures ultra-low power consumption and high linearity. The miniaturized high quality ( ${Q}$ ) factor SAW filters also lead to a low-loss nonreciprocal band with strong isolation (IX) and broad bandwidth (BW) on a chip scale, therefore addressing such limitations in previous magnet-free demonstrations. Furthermore, compared to the conventional differential circuit configuration, a novel quad configuration is developed, which doubles the intermodulation-free BW.
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radio frequency magnet free Circulators based on spatiotemporal modulation of surface acoustic wave filters
arXiv: Signal Processing, 2019Co-Authors: Giuseppe Michetti, Ahmed Kord, Dimitrios L Sounas, Andrea Alu, Michele Pirro, Zhicheng Xiao, Cristian Cassella, Matteo RinaldiAbstract:In this paper, a new generation of magnet-free Circulators with high performance is proposed. Circulators are crucial devices in modern communication systems due to their ability to enable full-duplexing and double the spectral efficiency directly in the physical layer of the radio-frequency (RF) front-end. Traditionally, Lorentz reciprocity is broken by applying magnetic bias to ferrite materials, therefore conventional Circulators are bulky and expensive. In this paper, this problem is addressed by replacing the magnetic bias with periodic spatiotemporal modulation. Compared to previous works, the proposed Circulator is constructed using surface acoustic wave (SAW) filters instead of transmission lines (TL), which reduces the modulation frequency by at least a factor of 20 and ensures ultra-low power consumption and high linearity. The miniaturized high quality (Q) factor SAW filters also lead to a low-loss non-reciprocal band with strong isolation (IX) and broad bandwidth (BW) on a chip scale, therefore addressing such limitations in previous magnet-free demonstrations. Furthermore, compared to the conventional differential circuit configuration, a novel quad configuration is developed, which doubles the intermodulation-free bandwidth.
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Nonlinearity-based Circulator
Applied Physics Letters, 2019Co-Authors: Giuseppe D'aguanno, Dimitrios L Sounas, Hady M. Saied, Andrea AluAbstract:Commercially available nonreciprocal devices, such as isolators and Circulators, play a fundamental role in communication systems. Since they commonly rely on magnetic materials, they tend to become bulky, expensive, and difficult to be integrated in conventional microelectronic circuits. Here, we explore the functionality of a magnetic-free Circulator where reciprocity is broken by suitable geometric asymmetries combined with tailored nonlinearities. We show that it is possible to operate a fully passive coupled resonator system without external bias like a Circulator for pulsed signals impinging at its ports within a desired range of intensities. The functionality can be applied to a variety of physical systems, ranging from electronics to photonics and acoustics.
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differential magnetless Circulator using modulated bandstop filters
International Microwave Symposium, 2017Co-Authors: Ahmed Kord, Dimitrios L Sounas, Andrea AluAbstract:In this paper, we present a differential magnetless Circulator by combining two angular-momentum-biased single-ended Circulators, each of which consists of three first-order bandstop LC filters connected in a delta topology and modulated in time with a phase difference of 120 deg between each other. Compared to a single-ended architecture, the differential one drastically reduces even-order intermodulation products, improves insertion loss, extends the bandwidth, and significantly decreases the required modulation frequency. We present the theory of such a Circulator and validate it with simulated and measured results.
Aravind Nagulu - One of the best experts on this subject based on the ideXlab platform.
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ultra compact ultra wideband dc 1ghz cmos Circulator based on quasi electrostatic wave propagation in commutated switched capacitor networks
Radio Frequency Integrated Circuits Symposium, 2020Co-Authors: Aravind Nagulu, Andrea Alu, Mykhailo Tymchenko, Harish KrishnaswamyAbstract:Recent research has revealed the possibility to achieve non-magnetic non-reciprocity using time-variance. However, prior CMOS-based Circulators rely on the interference between non-reciprocal switched-capacitor/transmission-line gyrators and reciprocal transmission-line rings, which increases form factor and restricts frequency tunability and bandwidth. On the other hand, recent works on quasi-electrostatic wave propagation in switched-capacitor media have demonstrated a new regime in multipath switched-capacitor network operation that enables an ultra-broadband, ultra-compact reciprocal/non-reciprocal true-time-delay element. In this work, we apply synthetic rotation across this quasi-electrostatic medium to realize an ultra-broadband N-port Circulator with ultra-compact form-factor. This new architecture is showcased in a wideband 3-port Circulator implemented in a standard 65nm CMOS process. This Circulator exhibits symmetric performance across all 3 ports and DC-1GHz operation for a modulation frequency of 500MHz. The measured transmission losses range between 3.1-4.3dB, matching is 18dB and NF is consistent with the insertion loss. This device occupies an area of 0.19mm2 ($\lambda _{center}^2/1.9 \times {10^6}$), representing about 100-1000× higher miniaturization compared to the prior art.
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a single antenna full duplex radio using a non magnetic cmos Circulator with in built isolation tuning
International Conference on Communications, 2019Co-Authors: Aravind Nagulu, Tingjun Chen, Gil Zussman, Harish KrishnaswamyAbstract:Wireless systems which can simultaneously transmit and receive (STAR) are gaining significant academic and commercial interest due to their wide range of applications such as full-duplex (FD) wireless communication and FMCW radar. FD radios, where the transmitter (TX) and the receiver (RX) operate simultaneously at the same frequency, can potentially double the data rate at the physical layer and can provide many other advantages in the higher layers. The antenna interface of an FD radio is typically built using a multi-antenna system, or a single antenna through a bulky magnetic Circulator or a lossy reciprocal hybrid. However, recent advances in CMOS-integrated Circulators through spatio-temporal conductivity modulation have shown promise and potential to replace traditional bulky magnetic Circulators. However, unlike magnetic Circulators, CMOS-integrated non-magnetic Circulators will introduce some nonlinear distortion and spurious tones arising from their clock circuitry. In this work, we present an FD radio using a highly linear CMOS integrable Circulator, a frequency-flat RF canceler, and a USRP software-defined radio (SDR). At TX power level of +15 dBm, the implemented FD radio achieves a self-interference cancellation (SIC) of +55 dB from the Circulator and RF canceler in the RF domain, and an overall SIC of +95 dB together with SIC in the digital domain. To analyze the non-linear phenomena of the CMOS Circulator, we calculated the link level data-rate gain in an FD system with imperfect SIC and then extended this calculation to count the effect of TX-RX non-linearity of the Circulator. In addition, we provide a qualitative discussion on the spurious tone responses of the Circulator due to the clocking imperfections and non-linearity.
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28 5 non magnetic 60ghz soi cmos Circulator based on loss dispersion engineered switched bandpass filters
International Solid-State Circuits Conference, 2019Co-Authors: Aravind Nagulu, Harish KrishnaswamyAbstract:There has been significant recent research on non-magnetic non-reciprocal components at RF and mm-waves, such as Circulators and isolators, based on spatio-temporal modulation [1-3]. Circulators enable simultaneous transmit and receive (STAR) on a shared antenna for applications such as full-duplex wireless communication and FMCW radar. While there has been exciting initial progress, existing architectures do not scale well to mm-waves, whether they are based on switch-based conductivity modulation [1, 2]or varactor-based permittivity modulation [3]. Loss levels increase due to losses in the switches or varactors, isolation is degraded due to reflections produced by parasitics, and power consumption is high due to the relatively high modulation frequencies required. In this work, we present a non-magnetic CMOS 60GHz Circulator based on spatiotemporal conductivity modulation (STCM) across a loss/dispersion-engineered bandpass filter. This new architecture improves the insertion loss, isolation, power consumption, and spurious response compared to prior art. The 60GHz Circulator achieves 3.6dB/3.1dB insertion loss for TX-to-ANT/ANT-to-RX paths, respectively, TX-to-RX isolation $> 40$dB over 1.3GHz, 3.2dB of ANT-to-RX NF, $> +19.5$dBm TX-to-ANT/ANT-to-RX IP 1dB S and spurious tones lower than -30dBc at both ANT and RX ports at a power consumption of 41mW from 1.2V.
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fully integrated non magnetic 180nm soi Circulator with 1w p1db 50dbm iip3 and high isolation across 1 85 vswr
Radio Frequency Integrated Circuits Symposium, 2018Co-Authors: Aravind Nagulu, Andrea Alu, Harish KrishnaswamyAbstract:There has been recent progress on CMOS non-magnetic Circulators based on switch-based spatio-temporal conductivity modulation, but these initial demonstrations remain limited in transmitter power handling, linearity, and ability to combat antenna variations. This paper describes a non-magnetic Circulator in 180nm SOI CMOS that uses no external components, and employs various linearity enhancement techniques such as device stacking, optimal switch biasing, and localized ESD design to achieve >1W TX-ANT PldB and >+50dBm TX-ANT IIP3 at 1GHz. A new loss-free and inductor-free antenna balancing approach enables high isolation for as high as 1.85 ANT VSWR and beyond. The Circulator also exhibits low insertion losses of 2.1dB/2.9dB in the TX-ANT and ANT-RX paths, and ANT-RX NF of 3.1dB. These results represent a 10–100×enhancement in linearity/power handling over prior CMOS non-reciprocal Circulators, and are shown to lower the power consumption of a communication link when compared with state-of-the-art electrical balance duplexers in scenarios where dynamic range is limited by P1dB, NF.
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a millimeter wave non magnetic passive soi cmos Circulator based on spatio temporal conductivity modulation
IEEE Journal of Solid-state Circuits, 2017Co-Authors: Tolga Dinc, Aravind Nagulu, Harish KrishnaswamyAbstract:Linear, time-invariant, passive circuits and systems constructed from conventional materials with symmetric permittivity and permeability tensors are reciprocal. Breaking Lorentz reciprocity enables the implementation of non-reciprocal components, such as gyrators, isolators, and Circulators, which find application in numerous wireless communication systems. Non-reciprocal components are traditionally implemented using ferrite materials, which exhibit the Faraday effect under the application of an external magnetic field bias. However, ferrite materials cannot be integrated into CMOS fabrication processes and require an external biasing magnet, and hence are bulky and expensive. Recently, there has been significant research interest in the implementation of non-magnetic non-reciprocal components using temporal modulation, including a fully integrated 25-GHz Circulator in a 45-nm SOI CMOS, demonstrating magnetic-free passive non-reciprocity on silicon at millimeter waves for the first time. This paper presents a detailed analysis of the millimeter-wave Circulator in both time and frequency domains. Millimeter-wave non-reciprocal operation is enabled by the concept of spatio-temporal conductivity modulation, which achieves broadband non-reciprocal gyrator functionality over theoretically infinite bandwidth (BW). When compared with prior approaches based on N-path filters, spatio-temporal conductivity modulation requires only four-phase 50% duty-cycle clocking at frequencies significantly lower than the operation frequency, enabling scaling to millimeter waves. The 25-GHz Circulator achieves minimum transmitter (TX)-to-antenna (ANT)/ANT-to-receiver (RX) insertion losses of 3.3 dB/3.2 dB, respectively, with a 1-dB BW of 4.6 GHz. TX-to-RX isolation is 18.3–21.2 dB (limited by the measurement setup) over the same BW. The Circulator IC occupies an area of 1.2 mm $\times $ 1.8 mm ( $\lambda /8 \times \lambda $ /6). The spatio-temporal conductivity modulation concept is readily scalable across frequency and can be an enabler for higher millimeter-wave (e.g., 77 GHz) Circulators as well as optical isolators.