The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
James F Buckwalter - One of the best experts on this subject based on the ideXlab platform.
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a Code Domain in band full duplex wireless communication link with greater than 100 db rejection
IEEE Transactions on Microwave Theory and Techniques, 2021Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Alfred Festus Davidson, Jonathan Tao, James F BuckwalterAbstract:This article presents a CMOS-based, Code-Domain (CD), full-duplex (FD) transceiver operating in a link at 1 GHz. The CD FD link rejects in-band transmitter self-interference (TX SI) by more than 100 dB through a combination of pseudo-noise (PN) Code orthogonality, circulator, and digital cancellation algorithms. A nonmagnetic CMOS circulator based on switched transmission lines is used as an antenna interface with >40-dB maximum rejection. Then, transmitter (TX) and receiver (RX) modulators spread the TX SI and correlate the desired RX signal in the RF Domain. Orthogonality between the PN Codes allows an additional >40-dB maximum rejection relaxing the FD transceiver linearity requirements. Finally, digital self-interference cancellation (SIC) eliminates any residual TX SI in the digital Domain using a least mean squares (LMS) estimation for the SI channel based on a nonlinear truncated Volterra series model. The digital SIC can have almost 40 dB of rejection depending on the SI power level. An implemented FD node leverages these techniques to achieve an overall rejection that is around 104 dB bringing the TX signal from 20 dBm to the noise floor of the RX at −85 dBm.
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a full duplex transceiver with cmos rf circulation and Code Domain signal processing for 104 db self interference rejection and watt level tx power handling
International Microwave Symposium, 2020Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Eythan Lam, James F BuckwalterAbstract:This paper describes a full-duplex (FD) radio transceiver that uses CMOS RFICs to realize high power handling and linearity. A high-rejection, magnetic-less CMOS circulator at the antenna along with high-rejection, blocker-tolerant RF Code-Domain correlators achieve high transmitter (TX) rejection in the RF Domain. Code-Domain operation supports higher linearity in FD applications. Digital cancellation increases the rejection down to noise floor of a software-defined radio (SDR). We compare the role of antenna impedance in the performance of SI rejection. The measured results demonstrate more than 104 dB TX self-interference (TX-SI) rejection at 20 dBm TX power. To the best of our knowledge, this work presents the best reported TX-SI rejection at more than 20 dBm.
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high rejection rf Code Domain receivers for simultaneous transmit and receive applications
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Ahmed Hamza, Hussam Alshammary, Cameron Hill, James F BuckwalterAbstract:Code-Domain signal processing techniques implemented at radio frequencies (RFs) enable simultaneous transmit and receive (STAR) applications. With direct sequence spread spectrum (DSSS) techniques and RF correlators, transmit (TX) self-interference (SI) is separated from the receive (RX) signal at the antenna interface for STAR. The processing gain inherent in the Code-Domain approach increases the TX SI rejection in the RF Domain to relax filtering and linearity requirements of the RX. A Code-Domain RX demonstrates 52 dB of TX SI rejection with TX Code-notch and RX Code-pass filters operating at the same center frequency. The RX is tunable from 0.25 to 1.25 GHz and has a gain of 39 dB at 1 GHz while consuming 90 mW of which 40 mW are consumed in the front-end filters. The RX is implemented in a 45-nm CMOS SOI process and full-duplex operation is verified through an over-the-air demonstration.
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a Code Domain rf signal processing front end with high self interference rejection and power handling for simultaneous transmit and receive
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Hussam Alshammary, Cameron Hill, Ahmed Hamza, James F BuckwalterAbstract:A Code-Domain transceiver front end that incorporates a transmit modulator and a receive (RX) RF signal correlator is presented. An integrate-and-dump $N$ -path filter improves rejection by 8 dB. We propose an RF chopper switch with 12.1-/23.1-dBm P1dB/IIP3 for both RF correlation and filtering that rejects TX self-interference by 49.5 dB. Walsh and Barker Codes are generated with fine and coarse tuning for synchronization. The RX power consumption is 18 mW, including dynamic power (1-V supply) and four analog amplifiers (1.5 V) at the operating frequency of 1 GHz and the Code rate of 200 megachip-per-second (Mc/s). The TX modulator operates to RF power levels up to 34.3 dBm and consumes less than 40 mW for 300 Mc/s. Over the air testing demonstrates synchronization with Barker Codes.
Ahmed Hamza - One of the best experts on this subject based on the ideXlab platform.
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a Code Domain in band full duplex wireless communication link with greater than 100 db rejection
IEEE Transactions on Microwave Theory and Techniques, 2021Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Alfred Festus Davidson, Jonathan Tao, James F BuckwalterAbstract:This article presents a CMOS-based, Code-Domain (CD), full-duplex (FD) transceiver operating in a link at 1 GHz. The CD FD link rejects in-band transmitter self-interference (TX SI) by more than 100 dB through a combination of pseudo-noise (PN) Code orthogonality, circulator, and digital cancellation algorithms. A nonmagnetic CMOS circulator based on switched transmission lines is used as an antenna interface with >40-dB maximum rejection. Then, transmitter (TX) and receiver (RX) modulators spread the TX SI and correlate the desired RX signal in the RF Domain. Orthogonality between the PN Codes allows an additional >40-dB maximum rejection relaxing the FD transceiver linearity requirements. Finally, digital self-interference cancellation (SIC) eliminates any residual TX SI in the digital Domain using a least mean squares (LMS) estimation for the SI channel based on a nonlinear truncated Volterra series model. The digital SIC can have almost 40 dB of rejection depending on the SI power level. An implemented FD node leverages these techniques to achieve an overall rejection that is around 104 dB bringing the TX signal from 20 dBm to the noise floor of the RX at −85 dBm.
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a full duplex transceiver with cmos rf circulation and Code Domain signal processing for 104 db self interference rejection and watt level tx power handling
International Microwave Symposium, 2020Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Eythan Lam, James F BuckwalterAbstract:This paper describes a full-duplex (FD) radio transceiver that uses CMOS RFICs to realize high power handling and linearity. A high-rejection, magnetic-less CMOS circulator at the antenna along with high-rejection, blocker-tolerant RF Code-Domain correlators achieve high transmitter (TX) rejection in the RF Domain. Code-Domain operation supports higher linearity in FD applications. Digital cancellation increases the rejection down to noise floor of a software-defined radio (SDR). We compare the role of antenna impedance in the performance of SI rejection. The measured results demonstrate more than 104 dB TX self-interference (TX-SI) rejection at 20 dBm TX power. To the best of our knowledge, this work presents the best reported TX-SI rejection at more than 20 dBm.
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high rejection rf Code Domain receivers for simultaneous transmit and receive applications
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Ahmed Hamza, Hussam Alshammary, Cameron Hill, James F BuckwalterAbstract:Code-Domain signal processing techniques implemented at radio frequencies (RFs) enable simultaneous transmit and receive (STAR) applications. With direct sequence spread spectrum (DSSS) techniques and RF correlators, transmit (TX) self-interference (SI) is separated from the receive (RX) signal at the antenna interface for STAR. The processing gain inherent in the Code-Domain approach increases the TX SI rejection in the RF Domain to relax filtering and linearity requirements of the RX. A Code-Domain RX demonstrates 52 dB of TX SI rejection with TX Code-notch and RX Code-pass filters operating at the same center frequency. The RX is tunable from 0.25 to 1.25 GHz and has a gain of 39 dB at 1 GHz while consuming 90 mW of which 40 mW are consumed in the front-end filters. The RX is implemented in a 45-nm CMOS SOI process and full-duplex operation is verified through an over-the-air demonstration.
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a Code Domain rf signal processing front end with high self interference rejection and power handling for simultaneous transmit and receive
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Hussam Alshammary, Cameron Hill, Ahmed Hamza, James F BuckwalterAbstract:A Code-Domain transceiver front end that incorporates a transmit modulator and a receive (RX) RF signal correlator is presented. An integrate-and-dump $N$ -path filter improves rejection by 8 dB. We propose an RF chopper switch with 12.1-/23.1-dBm P1dB/IIP3 for both RF correlation and filtering that rejects TX self-interference by 49.5 dB. Walsh and Barker Codes are generated with fine and coarse tuning for synchronization. The RX power consumption is 18 mW, including dynamic power (1-V supply) and four analog amplifiers (1.5 V) at the operating frequency of 1 GHz and the Code rate of 200 megachip-per-second (Mc/s). The TX modulator operates to RF power levels up to 34.3 dBm and consumes less than 40 mW for 300 Mc/s. Over the air testing demonstrates synchronization with Barker Codes.
Hussam Alshammary - One of the best experts on this subject based on the ideXlab platform.
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a Code Domain in band full duplex wireless communication link with greater than 100 db rejection
IEEE Transactions on Microwave Theory and Techniques, 2021Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Alfred Festus Davidson, Jonathan Tao, James F BuckwalterAbstract:This article presents a CMOS-based, Code-Domain (CD), full-duplex (FD) transceiver operating in a link at 1 GHz. The CD FD link rejects in-band transmitter self-interference (TX SI) by more than 100 dB through a combination of pseudo-noise (PN) Code orthogonality, circulator, and digital cancellation algorithms. A nonmagnetic CMOS circulator based on switched transmission lines is used as an antenna interface with >40-dB maximum rejection. Then, transmitter (TX) and receiver (RX) modulators spread the TX SI and correlate the desired RX signal in the RF Domain. Orthogonality between the PN Codes allows an additional >40-dB maximum rejection relaxing the FD transceiver linearity requirements. Finally, digital self-interference cancellation (SIC) eliminates any residual TX SI in the digital Domain using a least mean squares (LMS) estimation for the SI channel based on a nonlinear truncated Volterra series model. The digital SIC can have almost 40 dB of rejection depending on the SI power level. An implemented FD node leverages these techniques to achieve an overall rejection that is around 104 dB bringing the TX signal from 20 dBm to the noise floor of the RX at −85 dBm.
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a full duplex transceiver with cmos rf circulation and Code Domain signal processing for 104 db self interference rejection and watt level tx power handling
International Microwave Symposium, 2020Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Eythan Lam, James F BuckwalterAbstract:This paper describes a full-duplex (FD) radio transceiver that uses CMOS RFICs to realize high power handling and linearity. A high-rejection, magnetic-less CMOS circulator at the antenna along with high-rejection, blocker-tolerant RF Code-Domain correlators achieve high transmitter (TX) rejection in the RF Domain. Code-Domain operation supports higher linearity in FD applications. Digital cancellation increases the rejection down to noise floor of a software-defined radio (SDR). We compare the role of antenna impedance in the performance of SI rejection. The measured results demonstrate more than 104 dB TX self-interference (TX-SI) rejection at 20 dBm TX power. To the best of our knowledge, this work presents the best reported TX-SI rejection at more than 20 dBm.
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high rejection rf Code Domain receivers for simultaneous transmit and receive applications
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Ahmed Hamza, Hussam Alshammary, Cameron Hill, James F BuckwalterAbstract:Code-Domain signal processing techniques implemented at radio frequencies (RFs) enable simultaneous transmit and receive (STAR) applications. With direct sequence spread spectrum (DSSS) techniques and RF correlators, transmit (TX) self-interference (SI) is separated from the receive (RX) signal at the antenna interface for STAR. The processing gain inherent in the Code-Domain approach increases the TX SI rejection in the RF Domain to relax filtering and linearity requirements of the RX. A Code-Domain RX demonstrates 52 dB of TX SI rejection with TX Code-notch and RX Code-pass filters operating at the same center frequency. The RX is tunable from 0.25 to 1.25 GHz and has a gain of 39 dB at 1 GHz while consuming 90 mW of which 40 mW are consumed in the front-end filters. The RX is implemented in a 45-nm CMOS SOI process and full-duplex operation is verified through an over-the-air demonstration.
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a Code Domain rf signal processing front end with high self interference rejection and power handling for simultaneous transmit and receive
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Hussam Alshammary, Cameron Hill, Ahmed Hamza, James F BuckwalterAbstract:A Code-Domain transceiver front end that incorporates a transmit modulator and a receive (RX) RF signal correlator is presented. An integrate-and-dump $N$ -path filter improves rejection by 8 dB. We propose an RF chopper switch with 12.1-/23.1-dBm P1dB/IIP3 for both RF correlation and filtering that rejects TX self-interference by 49.5 dB. Walsh and Barker Codes are generated with fine and coarse tuning for synchronization. The RX power consumption is 18 mW, including dynamic power (1-V supply) and four analog amplifiers (1.5 V) at the operating frequency of 1 GHz and the Code rate of 200 megachip-per-second (Mc/s). The TX modulator operates to RF power levels up to 34.3 dBm and consumes less than 40 mW for 300 Mc/s. Over the air testing demonstrates synchronization with Barker Codes.
Arun Natarajan - One of the best experts on this subject based on the ideXlab platform.
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Code Domain multiplexing for shared if lo interfaces in millimeter wave mimo arrays
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Manoj Johnson, Kai Zhan, Arman Galioglu, Naresh Adepu, Sanket Jain, Harish Krishnaswamy, Armagan Dascurcu, Arun NatarajanAbstract:Millimeter-wave (mm-wave) multi-input–multi-output (MIMO) systems with the digitization of every element enable spatial multiplexing, virtual arrays for radar, and digital beamforming for high mobility scenarios. However, per-element digitization results in a formidable I/O challenge in large-scale tiled MIMO mm-wave arrays. This article analyzes a Code-Domain approach to multiplex signals from different elements as well as the LO on a single interface. System considerations are presented, and the approach is demonstrated through a 28 GHz four-element MIMO receiver in 65-nm CMOS. Measurements show the feasibility of digital beamforming after de-multiplexing of the baseband signals from the IF/LO interface. Each element in the array achieves 16-dB conversion gain while consuming 60 mA from 1.2 V. The IC occupies 5.75 mm2 in 65-nm CMOS, achieving small size and compatibility with $\lambda /2 \times \lambda /2$ antenna spacing due to the absence of phase shifters/combiners required in phased arrays.
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A 4-element 28 GHz Millimeter-wave MIMO Array with Single-wire Interface using Code-Domain Multiplexing in 65 nm CMOS
2019 IEEE Radio Frequency Integrated Circuits Symposium (RFIC), 2019Co-Authors: Manoj Johnson, Armagan Dascuru, Kai Zhan, Arman Galioglu, Naresh Adepu, Sanket Jain, Harish Krishnaswamy, Arun NatarajanAbstract:Millimeter-wave MIMO systems with digitization of every element enable spatial multiplexing, virtual arrays for radar, digital beamforming (DBF) for high mobility scenarios. However, per-element digitization results in a formidable I/O challenge in large-scale tiled MIMO mmWave arrays. This work demonstrates a 28GHz 4-element MIMO RX with a single-wire interface that multiplexes the baseband signals of all elements and the LO reference through Code-Domain multiplexing. System considerations are presented and the approach is validated through DBF after de-multiplexing of the baseband signals from the single wire. Each element in the array achieves 16 dB conversion gain while consuming 60 mA from 1.2 V. The IC occupies 5.75 mm2 in 65-nm CMOS.
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frequency Code Domain filtering using walsh function sequence based n path filters
International Microwave Symposium, 2019Co-Authors: Manoj Johnson, Abhishek Agrawal, Arun NatarajanAbstract:Applying orthogonal sequences to N-path filters promises reconfigurable select/reject filtering of signals based on their spatial, spectral and Code-Domain properties. Achieving Code and frequency-Domain notch filtering using inductors instead of capacitors has been challenging due to parasitics and self-resonance associated with large off-chip inductors. In this work, N-path frequency/Code-Domain reject and select filtering is demonstrated using N-path switching with passive inductors. A cascaded inductor approach and differential N-path filtering is used to overcome inductor parasitics and enable GHz operation. A 65-nm CMOS prototype of a Code-Domain notch filter followed by a Code-Domain select receiver demonstrates 0.5 GHz to 1.0 GHz operation with 26 dB blocker filtering with 8 dBm power handling, while consuming 60 mW (at 1 GHz LO) and occupying 1.2 mm2 of die area.
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An Interferer-Tolerant CMOS Code-Domain Receiver Based on N-Path Filters
IEEE Journal of Solid-State Circuits, 2018Co-Authors: Abhishek Agrawal, Arun NatarajanAbstract:This paper extends N-path filtering to the Code Domain by proposing Code-modulated local oscillator signals. A correlator-based perspective of N-path mixer receiver (RX) is presented to demonstrate interferer-rejection and desired signal reception in a Code-Domain N-path RX. Pairs of Walsh-function-based Codes are proposed for modulating desired RX and known interferers [such as self-interference (SI) from transmitter (TX)] to achieve high interferer rejection. An N-path architecture for concurrent reception of two Code-modulated signals is also presented. A 0.3-1.4-GHz 65-nm CMOS implementation achieves 35-dB gain for desired signals and concurrently receives two RX signals while rejecting mismatched spreading Codes at RF input. The proposed TX SI mitigation approach results in 38.5-dB rejection for -11.8 dBm 1.46-Mb/s quadrature phase-shift keying (QPSK) modulated SI at the RX input. The RX achieves 23.7-dBm output referred 1dB gain compression (OP1dB) for in-band SI, while consuming ~35 mW and occupies 0.31 mm2. Such Code-Domain selection/rejection can be used in conjunction with other N-path filtering schemes for signal selection/rejection based on a combination of spatial, spectral, and Code-Domain properties.
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a 0 3 ghz to 1 4 ghz n path mixer based Code Domain rx with tx self interference rejection
Radio Frequency Integrated Circuits Symposium, 2017Co-Authors: Abhishek Agrawal, Arun NatarajanAbstract:A Code-Domain N-path RX is proposed based on PN-Code modulated LO pulses for concurrent reception of two Code-modulated signals. Additionally, a combination of Walsh-Function and PN sequence is proposed to translate in-band TX self-interference (SI) to out-of-band at N-path RX output enabling frequency filtering for high SI rejection. A 0.3 GHz–1.4 GHz 65-nm CMOS implementation has 35 dB gain for desired signals and concurrently receives two RX signals while rejecting mismatched spreading Codes at RF input. Proposed TX SI mitigation approach results in 38.5 dB rejection for −11.8dBm 1.46 Mb/s QPSK modulated SI at RX input. The RX achieves 23.7dBm OP1dB for in-band SI, while consuming ∼35mW and occupies 0.31mm2.
Cameron Hill - One of the best experts on this subject based on the ideXlab platform.
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a Code Domain in band full duplex wireless communication link with greater than 100 db rejection
IEEE Transactions on Microwave Theory and Techniques, 2021Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Alfred Festus Davidson, Jonathan Tao, James F BuckwalterAbstract:This article presents a CMOS-based, Code-Domain (CD), full-duplex (FD) transceiver operating in a link at 1 GHz. The CD FD link rejects in-band transmitter self-interference (TX SI) by more than 100 dB through a combination of pseudo-noise (PN) Code orthogonality, circulator, and digital cancellation algorithms. A nonmagnetic CMOS circulator based on switched transmission lines is used as an antenna interface with >40-dB maximum rejection. Then, transmitter (TX) and receiver (RX) modulators spread the TX SI and correlate the desired RX signal in the RF Domain. Orthogonality between the PN Codes allows an additional >40-dB maximum rejection relaxing the FD transceiver linearity requirements. Finally, digital self-interference cancellation (SIC) eliminates any residual TX SI in the digital Domain using a least mean squares (LMS) estimation for the SI channel based on a nonlinear truncated Volterra series model. The digital SIC can have almost 40 dB of rejection depending on the SI power level. An implemented FD node leverages these techniques to achieve an overall rejection that is around 104 dB bringing the TX signal from 20 dBm to the noise floor of the RX at −85 dBm.
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a full duplex transceiver with cmos rf circulation and Code Domain signal processing for 104 db self interference rejection and watt level tx power handling
International Microwave Symposium, 2020Co-Authors: Ahmed Hamza, Harish Krishnaswamy, Hussam Alshammary, Cameron Hill, Aravind Nagulu, Eythan Lam, James F BuckwalterAbstract:This paper describes a full-duplex (FD) radio transceiver that uses CMOS RFICs to realize high power handling and linearity. A high-rejection, magnetic-less CMOS circulator at the antenna along with high-rejection, blocker-tolerant RF Code-Domain correlators achieve high transmitter (TX) rejection in the RF Domain. Code-Domain operation supports higher linearity in FD applications. Digital cancellation increases the rejection down to noise floor of a software-defined radio (SDR). We compare the role of antenna impedance in the performance of SI rejection. The measured results demonstrate more than 104 dB TX self-interference (TX-SI) rejection at 20 dBm TX power. To the best of our knowledge, this work presents the best reported TX-SI rejection at more than 20 dBm.
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high rejection rf Code Domain receivers for simultaneous transmit and receive applications
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Ahmed Hamza, Hussam Alshammary, Cameron Hill, James F BuckwalterAbstract:Code-Domain signal processing techniques implemented at radio frequencies (RFs) enable simultaneous transmit and receive (STAR) applications. With direct sequence spread spectrum (DSSS) techniques and RF correlators, transmit (TX) self-interference (SI) is separated from the receive (RX) signal at the antenna interface for STAR. The processing gain inherent in the Code-Domain approach increases the TX SI rejection in the RF Domain to relax filtering and linearity requirements of the RX. A Code-Domain RX demonstrates 52 dB of TX SI rejection with TX Code-notch and RX Code-pass filters operating at the same center frequency. The RX is tunable from 0.25 to 1.25 GHz and has a gain of 39 dB at 1 GHz while consuming 90 mW of which 40 mW are consumed in the front-end filters. The RX is implemented in a 45-nm CMOS SOI process and full-duplex operation is verified through an over-the-air demonstration.
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a Code Domain rf signal processing front end with high self interference rejection and power handling for simultaneous transmit and receive
IEEE Journal of Solid-state Circuits, 2020Co-Authors: Hussam Alshammary, Cameron Hill, Ahmed Hamza, James F BuckwalterAbstract:A Code-Domain transceiver front end that incorporates a transmit modulator and a receive (RX) RF signal correlator is presented. An integrate-and-dump $N$ -path filter improves rejection by 8 dB. We propose an RF chopper switch with 12.1-/23.1-dBm P1dB/IIP3 for both RF correlation and filtering that rejects TX self-interference by 49.5 dB. Walsh and Barker Codes are generated with fine and coarse tuning for synchronization. The RX power consumption is 18 mW, including dynamic power (1-V supply) and four analog amplifiers (1.5 V) at the operating frequency of 1 GHz and the Code rate of 200 megachip-per-second (Mc/s). The TX modulator operates to RF power levels up to 34.3 dBm and consumes less than 40 mW for 300 Mc/s. Over the air testing demonstrates synchronization with Barker Codes.