In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

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Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

This article reviews the state-of-the-art millimeter-wave (mm-wave) power amplifiers (PAs), focusing on broadband design techniques. An overview of the main solid-state technologies is provided, including Si, gallium arsenide (GaAs), GaN, and other III–V materials, and both field-effect and bipolar transistors. The most popular broadband design techniques are introduced, before critically comparing through the most relevant design examples found in the scientific literature. Given the wide breadth of applications that are foreseen to exploit the mm-wave spectrum, this contribution will represent a valuable guide for designers who need a single reference before adventuring in the challenging task of the mm-wave PA design.

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A Review of Technologies and Design Techniques of Millimeter-Wave Power Amplifiers

In this paper, an extended version of the continuous class-F-1 mode power amplifier (PA) design approach is presented. A new formulation describing the current waveform in terms of just two additional parameters, while maintaining a constant half-wave rectified sinusoidal voltage waveform, allows multiple solutions of fundamental and second-harmonic impedances that provide optimum performance to be computed. By varying only the imaginary parts of fundamental and second-harmonic impedances, it is shown that output performance in terms of power and efficiency is maintained constant and equal to that achievable from the standard class-F-1 . Indeed, when presenting resistive second-harmonic impedances, it will be demonstrated that the fundamental load can be adjusted to maintain satisfactory output performances greater than a certain predetermined target value. The measurements, conducted on a GaAs pHEMT device at 1 GHz, show a good agreement with the theoretical analysis, revealing drain efficiencies greater than 70% for a very large range of load solutions, which can translate to an ability to accommodate reactive impedance variations with frequency when designing broadband PAs.

The Continuous Inverse Class-F Mode With Resistive Second-Harmonic Impedance

GaN technology is not only gaining traction in power and RF electronics but is also rapidly expanding into other application areas including digital and quantum computing electronics. This paper provides a glimpse of future GaN device technologies and advanced modeling approaches that can push the boundaries of these applications in terms of performance and reliability. While GaN power devices have recently been commercialized in the 15–900 V classes, new GaN devices are greatly desirable to explore both higher-voltage and ultra-low-voltage power applications. Moving into the RF domain, ultra-high frequency GaN devices are being used to implement digitized power amplifier circuits, and further advances using the hardware–software co-design approach can be expected. On the horizon is the GaN CMOS technology, a key missing piece to realize the full-GaN platform with integrated digital, power, and RF electronics technologies. Although currently a challenge, high-performance p-type GaN technology will be crucial to realize high-performance GaN CMOS circuits. Due to its excellent transport characteristics and ability to generate free carriers via polarization doping, GaN is expected to be an important technology for ultra-low temperature and quantum computing electronics. Finally, given the increasing cost of hardware prototyping of new devices and circuits, the use of high-fidelity device models and data-driven modeling approaches for technology-circuit co-design are projected to be the trends of the future. In this regard, physically inspired, mathematically robust, less computationally taxing, and predictive modeling approaches are indispensable. With all these and future efforts, we envision GaN to become the next Si for electronics.

Emerging GaN technologies for power, RF, digital, and quantum computing applications: Recent advances and prospects

Total bandwidth of existing wireless communication technologies covers a wide frequency range of over one octave. But most existing power amplifier configurations cannot meet this requirement while at the same time maintaining a high efficiency. Therefore, a new structure that can achieve multioctave bandwidth is proposed in this paper together with the design methodology. The difficulty in realizing a bandwidth larger than one octave lies in the overlapping of fundamental and harmonic frequencies. Regarding this problem, the continuous class-F mode is extended to allow a resistive second harmonic impedance, rather than the pure reactive one. With the relaxed design requirements and overlapping design space of fundamental and second harmonic frequencies, harmonic tuning and fundamental frequency matching networks can be designed separately. More importantly, broadband matching for fundamental frequencies can be implemented simply by considering only three fundamental frequency points using the multiple frequencies matching method. To verify the validity of the proposed methodology, a multioctave power amplifier was designed, fabricated, and measured. Measured results verify a wide bandwidth of 128.5% from 0.5 to 2.3 GHz. Over this frequency range, drain efficiency was larger than 60% with output power greater than 39.2 dBm and large signal gain larger than 11.7 dB.

Design of Ultrawideband High-Efficiency Extended Continuous Class-F Power Amplifier

This letter introduces a theory which considers the effect of lossy second-harmonic terminations on the voltage waveform, output power, and efficiency of power amplifiers (PAs) operated in the class-J mode. To this end, the conventional (reactive) class-J mode is extended to a resistive-reactive class-J mode with complex fundamental and second-harmonic load impedances. The theory is experimentally validated by performing on-wafer active load-pull measurements on an AlGaN/GaN HEMT power device with $0.25~\mu{\rm m}$ gate length and a total gate periphery of $6\times 200~\mu{\rm m}$ . The measured waveforms are de-embedded to the internal current-generator of the device, where they exhibit the theoretically predicted behavior.

The Resistive-Reactive Class-J Power Amplifier Mode

In this article, we present a set of gallium nitride (GaN) power amplifiers (PAs) that provide state-of-the-art performance within the D-band (110–170 GHz) and G-band (140–220 GHz) frequencies. A four-stage cascode PA operates with more than 25 dB of small-signal gain over a 107–148-GHz band. At 120 GHz, it can deliver up to 26.4 dBm of output power and up to 16.5% of power-added efficiency (PAE) with more than 26 dB of gain at saturation. The combination of these parameters is among the best reported with a solid-state technology at such high frequencies. The two G-band circuits are able to provide up to 40 GHz of 3-dB bandwidth and gain exceeding 10 dB up to 190 GHz. The measured peak output power is 15.8 dBm at 181 GHz in 0.6-dB gain compression with a corresponding PAE of 2.4%. To the best of our knowledge, these amplifiers show the highest gain above 170 GHz and the highest output power above 150 GHz among any reported GaN-based MMICs.

D-Band and G-Band High-Performance GaN Power Amplifier MMICs

The design, realization, and characterization of a K-band high power amplifier with a saturated output power of 40dBm is described in this paper. The amplifier is realized using a 250nm gate length AlGaN/GaN HEMT MMIC technology on semi-insulating SiC substrates. The two-stage amplifier is designed with two 6×90 µm HEMT cells in the driver and four 8×100 µm HEMT cells in the final stage and thus exhibits a relatively aggressive staging ratio of 1∶3. When measured with a supply voltage of 32V, the amplifier delivers a saturated output power of 40dBm at 18 GHz. The peak PAE at this frequency is 30%, and the linear gain exceeds 20 dB. These results are state-of-the-art performance with regard to power/efficiency at K-band.

A 40 dBm AlGaN/GaN HEMT power amplifier MMIC for SatCom applications at K-band

This paper reports on the analysis, development and results of a wideband High Power Amplifier (HPA) covering a large segment of the Ka-Band. The presented circuit has been manufactured in a GaN-on-SiC process with a gate length of 100 nm with three different process variants. It reaches a linear gain of well over 22 dB and an output power between 6 and 9 W in the band of 26 to 35 GHz, which equals a fractional bandwidth of over 29 %, while also maintaining a state-of-the-art power-added efficiency. To the best of the authors’ knowledge, this is the most broadband HPA over 7 W published in this frequency band.

Design, Analysis and Evaluation of a Broadband High-Power Amplifier for Ka-Band Frequencies

In this article, we summarize the theoretical matching boundaries and show the limitations they implicate for real-world amplifier design. Starting with a common schematic prototype, we investigate the question of how to realize its electrical response in a densely routed, massively parallelized layout. To that end, we develop a comprehensive study on the application of space-mapping techniques toward the design of high-power amplifiers (HPAs). We derive three reference design procedures and compare their performance in terms of convergence, speed, and practicality when laying out a densely routed HPA interstage matching network. Subsequently, we demonstrate the usefulness of the study by designing the networks of a compact three-stage eight-way wideband HPA in the Ka-band. The processed monolithic microwave integrated circuit features a 1-dB large-signal bandwidth of more than 11 GHz (a fractional bandwidth of 32.8%) and thus covers most of the Ka-band with an output power exceeding 6 W in 3 dB of gain compression. This demonstrates the highest combination of power and bandwidth to date using a reactively matched topology in the Ka-band.

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Christian Friesicke

Papers

The Resistive-Reactive Class-J Power Amplifier Mode

D-Band and G-Band High-Performance GaN Power Amplifier MMICs

A 40 dBm AlGaN/GaN HEMT power amplifier MMIC for SatCom applications at K-band

Design, Analysis and Evaluation of a Broadband High-Power Amplifier for Ka-Band Frequencies

Limitations and Implementation Strategies of Interstage Matching in a 6-W, 28–38-GHz GaN Power Amplifier MMIC