Ge Wu

Bio: Ge Wu is an academic researcher from University of Calgary. The author has contributed to research in topics: CMOS & Buffer amplifier. The author has an hindex of 5, co-authored 10 publications receiving 83 citations.

Wideband $N$ -Beam Arrays Using Low-Complexity Algorithms and Mixed-Signal Integrated Circuits

Abstract: This paper proposes a low-complexity wideband beamforming subarray for millimeter wave (mmW) 5G wireless communications. The multibeam subarray is based on using a novel delay Vandermonde matrix (DVM) algorithm to efficiently generate analog true-time-delay beams that have no beam squint. A factorization for the DVM leading to low-complexity analog realizations is provided and complexity analysis for real and complex inputs is derived. The DVM is a special case of a Vandermonde matrix but with complex nodes that lack any special properties (unlike the discrete Fourier transform matrix). Error bounds for the DVM are established and then analyzed for numerical stability. Mixed-signal CMOS integrated circuits designs are proposed for the implementation of DVM multibeam algorithms along with low-complexity digital realizations to achieve hybrid beamforming for mmW applications. Analog–digital hybrid mmW multibeam beamforming circuits and systems are designed, for example, with eight beams at 28 GHz and simulated in cadence for functional verification.

5-bit 5-GS/s Noninterleaved Time-Based ADC in 65-nm CMOS for Radio-Astronomy Applications

Abstract: This paper presents a 5-bit noninterleaved time-based analog-to-digital converter (ADC), which operates at a 5-GS/s rate. The ADC is designed for the use in radio-astronomy telescopes, for which time interleaving is not acceptable. The ADC employs a dynamic, differential voltage-to-time converter, a folded-flash time-to-digital converter (TDC), and calibration circuitry. To generate reference delays, the calibration circuitry utilizes a delay-time reference network, which is designed to map the input voltage range into 16 equal time intervals that are used for the calibration of the TDC. The 65-nm CMOS ADC achieves the Signal-to-noise plus distortion ratio/spurious-free dynamic range of 27/32 dB at Nyquist, an effective number of bits (ENOB) of 4.7 bit at low frequencies and 4.1 bit at high frequencies with a power consumption of 21.5 mW at Nyquist.

Wide-Band Two-Stage GaAs LNA for Radio Astronomy

Abstract: This paper presents the design, simulation and measurements of wideband two-stage LNAs using commercially available discrete components and targeting Square Kilometre Array (SKA) focalplane-array verification studies. The design optimization was implemented through simulations based on theoretical work that shows that low wide-band noise figures and power match are achievable by inner-stage component selection and device bias. In contrast to the conventional practice of having each stage of a discrete LNA matched to 50Ω, the inner stage was designed with a mismatching capacitor between the two stages. The measured results are presented for 0.7–1.4 GHz and achieve noise figures below 0.4 dB, gain of at least 28 dB, mid-band input return loss of 7 dB, output P1dB of 18.3 dBm, input-referred IP3 of −15.47 dBm, and power consumption of 500mW with a supply voltage of 5V.

A broadband automatic gain control amplifier for the Square Kilometer Array

Abstract: In this paper, a low-power broadband automatic-gain-control (AGC) amplifier targeted for use in the Square Kilometer Array (SKA) [1] is presented. The AGC is composed of an input power-match circuit, a linear-in-dB output variable gain amplifier (VGA), a power detector (PD), an error amplifier, a comparator and a loop filter. The input stage is power matched to 100Ω differential source impedance, achieves an input reflection coefficient of less than −15.6dB and maximum noise figure of 2.6dB from 0.5GHz to 2.0GHz. The VGA has a variable gain range of 29dB and −3dB bandwidth of 4GHz. The square-law relationship between output current and gate-source voltage characteristics of a MOS transistor working in the strong inversion region is used for power detection. The −3dB bandwidth of the AGC amplifier is 2.65GHz with and 3.6GHz without the power-match circuit. The input operating range of the AGC is from −50dBm to −20dBm. The design is based on a commercial 65nm CMOS technology with a 1V power supply. The total power consumption of the AGC is 6mW of which 4.5mW is consumed by the input-match circuit which is not needed when the AGC is integrated in the SKA receiver.

A 65nm CMOS 0.1–2.1GHz linear-in-dB VGA with active-inductor bandwidth extension for the Square Kilometer Array

Abstract: In this paper, a 65nm CMOS broadband linear-in-dB Variable-Gain Amplifier (VGA) circuit for use in the Square Kilometer Array (SKA) is proposed. Active inductor loads are used to extend the 3dB bandwidth of the VGA over previous designs. Measurements show that the VGA is broadband, has a 3dB upper band edge of 2.1GHz, and easily covers the mid-band SKA range from 0.7GHz to 1.4GHz. The VGA has a maximum controllable gain range from −12.5dB to +22.4dB and a linear-in-dB range with 1dB error from −12.5dB to +16dB. Measured input P1dB is approximately −22dBm. The power consumption of the VGA is 1.1mW with another 5.1mW consumed by an input-match circuit and 11mW consumed by an output buffer circuit.

Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond

Abstract: Frequencies from 100 GHz to 3 THz are promising bands for the next generation of wireless communication systems because of the wide swaths of unused and unexplored spectrum. These frequencies also offer the potential for revolutionary applications that will be made possible by new thinking, and advances in devices, circuits, software, signal processing, and systems. This paper describes many of the technical challenges and opportunities for wireless communication and sensing applications above 100 GHz, and presents a number of promising discoveries, novel approaches, and recent results that will aid in the development and implementation of the sixth generation (6G) of wireless networks, and beyond. This paper shows recent regulatory and standard body rulings that are anticipating wireless products and services above 100 GHz and illustrates the viability of wireless cognition, hyper-accurate position location, sensing, and imaging. This paper also presents approaches and results that show how long distance mobile communications will be supported to above 800 GHz since the antenna gains are able to overcome air-induced attenuation, and present methods that reduce the computational complexity and simplify the signal processing used in adaptive antenna arrays, by exploiting the Special Theory of Relativity to create a cone of silence in over-sampled antenna arrays that improve performance for digital phased array antennas. Also, new results that give insights into power efficient beam steering algorithms, and new propagation and partition loss models above 100 GHz are given, and promising imaging, array processing, and position location results are presented. The implementation of spatial consistency at THz frequencies, an important component of channel modeling that considers minute changes and correlations over space, is also discussed. This paper offers the first in-depth look at the vast applications of THz wireless products and applications and provides approaches for how to reduce power and increase performance across several problem domains, giving early evidence that THz techniques are compelling and available for future wireless communications.

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

Abstract: This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

Phased Arrays for Radio Astronomy, Remote Sensing, and Satellite Communications

Abstract: Discover a modern approach to the analysis, modeling and design of high sensitivity phased arrays. Network theory, numerical methods and computational electromagnetic simulation techniques are uniquely combined to enable full system analysis and design optimization. Beamforming and array signal processing theory are integrated into the treatment from the start. Digital signal processing methods such as polyphase filtering and RFI mitigation are described, along with technologies for real-time hardware implementation. Key concepts from interferometric imaging used in radio telescopes are also considered. A basic development of theory and modeling techniques is accompanied by problem sets that guide readers in developing modeling codes that retain the simplicity of the classical array factor method while incorporating mutual coupling effects and interactions between elements. Combining current research trends with pedagogical material suitable for a first-year graduate course, this is an invaluable resource for students, teachers, researchers, and practicing RF/microwave and antenna design engineers.

High-Sensitivity Phased Array Receivers for Radio Astronomy

Abstract: Phased arrays have a long history in radio astronomy. Large, sparse synthesis arrays have been in use for decades to capture high-resolution images of deep space objects. More recent work has extended the range of applications to other types of arrays, including aperture arrays (AAs) and phased array feeds (PAFs) for multibeam reflector antennas. The extreme sensitivity required for astronomical instrumentation is driving advances in numerical electromagnetic modeling, design optimization of large arrays, low noise amplifiers, minimization of receiver noise, cryogenic PAFs, array calibration, optimal beamforming, interferometric imaging, and array signal processing algorithms for radio-frequency interference mitigation. We give an overview of research progress, current and planned array-based instruments, and open challenges in these areas related to the new generation of sparse arrays, PAFs, and AAs that are in development for astronomical observatories around the world.