Antenna load impedance variations typically cause significant power amplifier (PA) performance degradation, including output power, large-signal linearity, and peak/average PA efficiency, which are especially critical for modern millimeter-wave (mm-Wave) communications with spectrally efficient complex modulations. To address this problem, we propose a reconfigurable hybrid series/parallel Doherty PA with a 90°-coupler-based active load modulation network. By reconfiguring the series/parallel Doherty operation modes, the strengths of the Main/Auxiliary PAs, and their relative phase, linear output power ( ${\mathrm {OP}}_{1{\mathrm{ ~dB}}}$ ), as well as peak output power ( $P_{\mathrm {sat}}$ ) and energy efficiency (PAEpeak and ${\mathrm {PAE}}_{1{\mathrm{ ~dB}}}$ ) of the PA can be largely restored under full-span 360° antenna impedance variations. The theoretical analysis and design guidelines are both presented in this article. As a proof of concept, a 39-GHz reconfigurable hybrid series/parallel Doherty PA is fabricated in the Global Foundries 45-nm RF CMOS silicon on insulator (SOI) process with a 2-V PA supply and 1-V driver supply. At 39 GHz, the PA achieves a 33.3% peak power-added efficiency (PAE) at 20.8-dBm $P_{\mathrm {sat}}$ and 32.2% ${\mathrm {PAE}}_{1{\mathrm{ ~dB}}}$ at 20.2-dBm ${\mathrm {OP}}_{1{\mathrm{ ~dB}}}$ at a nominal 50- $\Omega $ load. The reconfigured PA demonstrates an 18.5–19.12-dBm ${\mathrm {OP}}_{1{\mathrm{ ~dB}}}$ with a high ${\mathrm {PAE}}_{1{\mathrm{ ~dB}}}$ of 20.6%–25.3% at 3:1 antenna voltage standing wave ratio (VSWR) over 360° angles. The PA achieves an rms error vector magnitude (EVM) of −23.6 dB/−22.8 dB/−23.1 dB at an average $P_{\mathrm {out}}$ of 13.8 dBm/12.2 dBm/11.5 dBm with 100 MSym/S/500 MSym/S/1 GSym/S single-carrier 64-quadratic-amplitude modulation (QAM) signal, respectively, at a nominal load of 50 $\Omega $ . A greater-than 11.2-dBm average $P_{\mathrm {out}}$ is achieved at an rms EVM of −24 dB under a full-span 3:1 antenna VSWR with a 100-MSym/S 64-QAM signal.

A Reconfigurable Hybrid Series/Parallel Doherty Power Amplifier With Antenna VSWR Resilient Performance for MIMO Arrays

This article presents a wideband millimeter-wave (mmWave) receiver front-end that covers the frequency range from 43 to 97 GHz, supporting the operation in the major parts of the V-, E-, and W-bands. The front-end incorporates a passive mixer-first topology to achieve high linearity and wideband performance. The front-end adopts I/Q generation at the RF port, using a coupled-line coupler (CLC), rather than at the local oscillator (LO) port to mitigate the crosstalk of the overlapping I/Q LO signals especially present at high frequencies. The CLC at the RF input facilitates ultrawide band input matching. The front-end implements the multi-gate gm3 cancellation technique at the IF amplifiers to preserve the linearity and provide gain at the IF section. Image rejection capabilities using a current mode transformer-based IF 90° coupler are implemented on chip and demonstrated with measurements. The front-end prototype is fabricated on the GlobalFoundries 22-nm FD-SOI CMOS process and it demonstrates an ultra-wideband performance across the frequency range 43–97 GHz (2.25:1 bandwidth) with image rejection of up to 32 dB, IIP3 of 1.6–5.2 dBm, and gain of 15 dB. The implementation used is low-IF topology with 3.8-GHz IF frequency and 1-GHz bandwidth. Furthermore, the measurement results show that the front-end supports high-speed modulated signals of up to 6-Gbps 64QAM modulation data.

A 43–97-GHz Mixer-First Front-End With Quadrature Input Matching and On-Chip Image Rejection

An autonomous beamformer demonstrates multi-beam and multi-band signal transmission and reception with wide field-of-view (FoV) self-steering beam-tracking/-forming for future extreme broadband and dynamic mm-Wave fronthaul applications operating in 5G new radio (NR) frequencies. The experimental results show the novel autonomous beamformer system covering full FoV beamforming (180°) with a wideband 22–40 GHz home-designed antenna array, demonstrating simultaneously multi-band (24.75 and 37 GHz) signals receiving with enhanced mobile multi-Gb/s transmission. A system testbed is further implemented to achieve a mm-Wave bi-directional link between remote radio unit (RRU) and user equipment (UE) in a fiber-wireless integrated network. A wide FoV autonomous signal sensing for angle-of-arrival (AoA) information in receiver is fed forward for mirror-reversed multi-Gb/s signal transmitting over a 10-km fiber and 0.56-m wireless link, addressing fast-changing complex 5G transceiver alignments. To the best of our knowledge, this is the first demonstration of an integrated autonomous beamformer for mm-Wave multi-beam and multi-band mobile applications in a fiber-wireless integrated radio access network.

A Bi-Directional Multi-Band, Multi-Beam mm-Wave Beamformer for 5G Fiber Wireless Access Networks

This article presents a $Ka$ -band bidirectional transceiver front end and its integration in an image-reject up/down converter module in 28-nm bulk CMOS. In the radio frequency (RF) front end, a transformer-based transmit/receive (T/R) switch is exploited for minimum area occupation without affecting the linearity and the isolation between the transmitter (TX) and receiver (RX) paths. The TX front end shows 19-dB power gain with an output-referred ${\mathrm{ OP}}_{\mathrm{ 1\,dB}}$ of 14 dBm and 18.7% power-added efficiency (PAE). Tested with a 100-MHz 64-QAM orthogonal frequency-division multiplexing (OFDM) modulated input signal, the error vector magnitude (EVM) is below 5% up to an average output power of 6.6 dBm, with a corresponding 7% PAE. The RX in the front end features a minimum noise figure (NF) of 4.9 dB, with 17-dB power gain. The measured input IP3 is –9.2 dBm, while the power consumption is only 35 mW. The RF bandwidth is 22–31 GHz, wide enough to cover the fifth-generation (5G) new radio (NR) bands n257, n258, and n261. The RF front end is also monolithically integrated along with a broadband bidirectional frequency up/down converter, capable of translating the 5G modulated signal from/to a 3-GHz intermediate frequency (IF). The up/down converter is realized with a single bidirectional quadrature mixer shared between the TX and RX paths. At the IF, a single hybrid coupler is used for quadrature phase shifting in upconversion and recombination in downconversion while concurrently keeping the TX and RX IF paths isolated from each other. In the upconversion mode, the module features a 22-dB programmable conversion gain, with a 40-dB minimum in-band image rejection ratio (IRR). The downconversion path shows a 29-dB programmable conversion gain and a minimum measured NF and IRR of 8.5 and 30 dB, respectively, while consuming 110 mW.

A Broadband 22–31-GHz Bidirectional Image-Reject Up/Down Converter Module in 28-nm CMOS for 5G Communications

This letter presents two pseudo-differential ring amplifiers (RAs) suitable for a continuous-time (CT) operation as an alternative to traditional amplifiers. The designs retain the advantages of RAs, scale with process technology, and do not require a periodic reset. The RAs are designed to operate in an integrator configuration and use different methods to achieve stability in continuous time. A prototype was fabricated in a 65-nm CMOS containing two versions of a CT delta–sigma ADC using the two RAs presented. The ADCs consist of a fourth-order loop filter with optimized zeros, a single-bit quantizer that operates at a sampling frequency of 320 MHz, and a digital-to-analog converter. The best design proposed achieves a measured peak signal-to-noise and distortion ratio of 50.6 dB for an 8-MHz bandwidth, a dynamic range of 53.2 dB, and consumes 152 ${\mu }\text{W}$ at a supply of 1.1 V. The obtained figure of merit is 34.3 fJ/conv.-step which outperforms state-of-the-art delta–sigma ADCs in that specification range and is 77% superior to its traditional operational transconductance amplifier-based ADC counterpart.

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34.3 fJ/conv.-step 8-MHz Bandwidth Fourth-Order Pseudo-Differential Ring-Amplifier-Based Continuous-Time Delta–Sigma ADC in 65 nm

This work presents an ultra-wideband mixer-first front-end that can cover mmWave communications bands in the frequency range 43–97 GHz. The front-end employs a mmWave 90°coupler as an input stage in order to achieve wideband matching and RF quadrature signal generation. Passive mixer and multi-gated gm3-cancellation IF amplifiers used to achieve and maintain high linearity across the frequency range. In addition, the frond-end implements a current mode image rejection using a transformer based IF 90°coupler. The receiver front-end is implemented in CMOS 22nm FD-SOI technology and achieves an ultra-wideband S11 matching while employing up to 32 dB image rejection and 1.6-5.2 dBm in-band IIP3. In addition, the front-end supports up to 6 Gbps 64QAM modulated data.

Mixer-First Extremely Wideband 43–97 GHz RX Frontend with Broadband Quadrature Input Matching and Current Mode Transformer-Based Image Rejection for Massive MIMO Applications

This paper presents a novel ring amplifier for continuous-time (CT) circuits. The proposed amplifier enables the usage of ring amplifier in continuous-time applications. The design parameters of the proposed architecture are discussed and analyzed. A CT second order Sigma-Delta (ΣΔ) modulator is designed using the proposed architecture achieving SNDR of 61.7 dB at signal BW of 1 MHz and sampling frequency of 104 MHz. The modulator is implemented in a 65 nm CMOS process and consumes 490 μW from a single 0.9 V power supply.

A Ring Amplifier Architecture for Continuous-Time Applications

In this paper, a mixed-mode self-calibrated Automatic Gain Control (AGC) loop for MEMS applications is introduced. In MEMS-based vibratory gyroscope systems, an AGC is used to regulate the vibration amplitude of an inertia mass. Traditional analog AGCs suffer from a limited control range or bulky elements. Here, we present a low gain P-controller (Fine tuning) with digitally-controlled dynamic bias (Coarse tuning) for the AGC loop. The dynamic bias compensates for the low loop gain through the AGC and is generated using an error sense ADC. This approach achieves more than 9bits of uncalibrated oscillation amplitude accuracy over PVT without the need for trimming the gyroscope actuation gain. The power consumption of the designed main amplitude control circuitry is less than 200µW. The overall circuit was built using a standard 0.13µm CMOS technology.

Mixed-mode self-calibrated amplitude control scheme for MEMS vibratory gyroscopes

Next-generation wireless communication systems mandate extreme data-rates (multi-Gb/s), ultra-low latency, and fast response, necessitating the use of mm-Wave frequency bands. To maximize the channel capacity, polarization MIMOs are gaining increasing attentions, which simultaneously transmit two independent data streams using the orthogonal polarization modes on the same frequency channel [1–8]. On the other hand, polarization misalignment between the transmitting and receiving antennas will result in cross-polarization contamination between both signal streams as well polarization mismatch signal loss. Traditionally, this is corrected using backend digital processing, which is sufficient for applications in static or slowly varying environments and fixed wireless accesses, such as, backhaul, customer premise equipment (CPE), and data center. However, for future latency-sensitive mobile applications especially in highly dynamic and rapidly changing channel environments, real-time recurrent polarization realignments are needed, and the backend processing time will cause major penalty on link latency and response time. To address this challenge, we present a polarization MIMO receiver (RX) architecture that utilizes frontend mixed-domain feedback loops on signal polarizations; without any backend DSP computation, the RX achieves rapid autonomous polarization alignment in micro-seconds $(\mu s)$ and enables future ultra-low latency and extreme-data-rate polarization MIMOs for highly dynamic and mobile applications.

A 26-32 GHz Dual-Polarization Receiver with Autonomous Polarization Alignment for Fast-Response Mm-Wave MIMO Links in Highly Dynamic Mobile Environments

Amr Ahmed

Papers

A 43–97-GHz Mixer-First Front-End With Quadrature Input Matching and On-Chip Image Rejection

Mixer-First Extremely Wideband 43–97 GHz RX Frontend with Broadband Quadrature Input Matching and Current Mode Transformer-Based Image Rejection for Massive MIMO Applications

A Ring Amplifier Architecture for Continuous-Time Applications

Mixed-mode self-calibrated amplitude control scheme for MEMS vibratory gyroscopes

A 26-32 GHz Dual-Polarization Receiver with Autonomous Polarization Alignment for Fast-Response Mm-Wave MIMO Links in Highly Dynamic Mobile Environments