HRL provides winning solutions for challenging system requirements, with outstanding expertise and capabilities in state-of-the-art microwave/millimeter-wave devices, mixed signal integrated circuits (ICs) and novel approaches to low cost IC reconfigurable front ends. We apply "nano" in every aspect of our work. We have developed several key technology discriminators. We deliver high yield indium phosphide heterojunction bipolar transistor (InP HBT) ICs for high speed mixed signal circuits at low power and millimeter-wave-frequency power amplifiers and low noise amplifiers. We also produce gallium nitride (GaN) devices for high-power amplifiers and high temperature operation. Our antimony-based compound semiconductors (ABCS) operate with extreme low power and our tunable impedance surfaces for antennas and miniature tunable filters define the state of the art. HRL's technology expertise spans competencies in design, analysis and synthesis, fabrication, testing, packaging, and assembly, to offer solutions for the most challenging customer needs.

Our offerings range from basic research to production for system requirements. We target high reliability components that are cutting edge discriminators. Our components fly in satellites and military aircraft, and our expertise supports microelectronic implementation in ground vehicles.

Our IC designers have a world-class reputation in continuous-time delta-sigma analog-to-digital converter design and in microwave and millimeter-wave-frequency electronic (ICs, antennas, filters, boards) design. In addition to experience in the extreme performance semiconductors, we pioneered design and modeling analysis into SiGe foundries and we have commercial RF CMOS design expertise. We develop models for simulation and employ a full suite of leading edge commercial design tools. To supplement these, we develop algorithms and tools for addressing uniquely demanding regimes such as very high frequencies and sub-system simulation.

We have focused on the challenges of analog to digital converters (ADCs), digital to analog converters (DACs), direct and indirect frequency synthesis (direct digital synthesis and phase locked loop), high-speed digital communication ICs, and opto-electronic integrated circuits (OEICs). Innovations in advanced circuit architectures, new circuit concepts, and the highest performance mixed-signal ICs have evolved from internal investments and Government Contract Research and Development (CRAD).

For novel antenna and variable impedance surface structure design and analysis, we utilize commercial codes (e.g., FEKO) and enhancements to HRL's own electromagnetic scattering codes. In high speed ADC design, we use commercial CAD tools (e.g., Cadence) supplemented with our internally developed HAARSPICE software for accelerating the simulation of transient effects (typical of initial signal acquisition in RF sensors and structural dynamics in vehicular crash simulations).

Our LLC Members and customers also design into our extreme performance semiconductor technologies. We fabricate a variety of components in our 10,000-square-foot Class-10 clean room. Our design expertise is matched by world class experts in materials, devices, and fabrication technologies, to develop and produce high-performance components for system insertion.

Our materials team is equipped with state-of-the-art molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) tools for semiconductor heterostructure growth. We work with a variety of substrate vendors to develop optimal requirements for circuit fabrication. Compatible with 4-inch wafer handling, our lithography tools include 0.05-micrometer (i.e., 50-nanometer) electron-beam and 0.30-micrometer ultraviolet lithography tools, which achieve minimum feature sizes and layer-to-layer registration down to 50 nanometers. These capabilities are augmented by plasma deposition, etching, and metallization systems.

Complementing our fabrication and design capabilities are expertise and facilities for testing high-performance electronic devices and circuits to 170 GHz, and for testing of antenna and filter structures into Ka-band (typical 35 GHz). We are currently upgrading our test capabilities to reach even higher frequency regimes. As our components push towards higher frequencies, packaging and assembly technologies present new challenges as well. We are currently providing packaged microelectronic components with operating frequencies above 60 GHz with easy-to-use connectors. We are combining these components with control circuitry, miniature tunable filters, and sophisticated antennas to create new capabilities.

We deliver products from the current generation of InP HBTs and are driving the next generation for a 10-times power reduction, 10-times circuit density increase, and 3-times improvement in speed.
The new generation of technology combines the benefits of InP fast electron transport with the scaling capabilities of silicon-based HBTs to produce 20,000-transistor ultra-high-performance circuits. This level of integration offers the prospect of producing digital synthesizer circuits at X-band using conventional techniques. Coupled with advanced circuit techniques, digital synthesis of signals up to 40 GHz becomes feasible.

We recently developed a Direct Digital Synthesizer (DDS) IC in our DARPA-funded HRL Technology for Frequency Agile Digitally Synthesized Transmitters (TFAST) InP-based HBT technology. These InP-based DDS chips have demonstrated a signal output at a world record frequency of 5.5 GHz, much higher than available with silicon IC technology (Figure 1). The individual InP transistors alone operate at cutoff frequencies above 400 GHz. They have previously enabled 150-GHz digital divider circuits to operate with DC power consumption as little as 90 milliwatt per gate–roughly one-third that required by our competitor's best circuits.



Direct digital synthesis is a method for producing high linearity signals for application in products ranging from consumer stereo receivers to advanced exciters in digital radars. Direct digital synthesis is attractive for this broad range of applications for many reasons, including high-frequency resolution and frequency-agile switching over a broad range of output frequencies.

For even lower power high-speed ICs (important, for example, in unattended sensors or mobile sensors or satellites), HRL is developing ultra-low-power, high-frequency, mixed-signal ICs based on indium arsenide (InAs), currently at mid-to-large-scale integration levels. The power-delay (or power-density-delay) performance is far greater at low power than is currently achievable with any other IC technology at frequencies above 10 GHz. HRL has demonstrated circuits using 0.4-micrometer-emitter InAs-based HBTs with transistors having very low turn-on voltages (0.35 volt) and at cutoff frequencies >215 GHz. These devices enabled the demonstration of digital divider ICs in which the transistors consumed only 361 microwatts of DC power while switching at frequencies up to 36 GHz (Figure 2).



Our InAs-channel high electron mobility transistor (HEMT) technology with the high electron mobility and velocity in InAs supports transistors enabling very-low-power millimeter-wave MMICs and sub-millimeter-wave MMICs for such applications as high-resolution imaging systems and communication systems. We have developed InAs-channel HEMTs that exhibit operating cutoff frequencies above 300 GHz at very low bias voltage. Unlike other devices of this type, our devices maintain gain at low voltages, permitting much lower-power operation.

While we are extending InP HEMT MMIC technology to higher frequencies (i.e., 150 GHz to 400 GHz), we are also producing W-band (75 to 110 GHz) power amplifiers and low-noise amplifiers for multiple customer needs. These devices are compatible with our novel zero-bias backward-tunnel diodes, useful for W-band sensors with essentially zero noise. Recent research advances in our HEMT technology have enabled us to demonstrate a MMIC with 15-to-25 milliwatts of output power over the 140-to-170 GHz band. Another dramatic advance for HRL was our demonstration of the world's first transistor-based active MMIC at 300 GHz (Figure 3).



Recent advances such as development of a 50-nanometer gate will enable further progress on these HEMTs to support even higher operating frequencies. In addition, these technologies are key building-block modules for the development of single-electron, quantum bits, and electron-spin-based electronic signal processing (Figure 4).




Gallium nitride components are capable of handling very high power, delivering tens of watts from a single device, and can withstand much higher operating temperatures than traditional semiconductors. This technology offers new sensing and control capabilities for harsh environments, such as internal to an engine.

HRL has a proven capability for fabrication, design, and testing of high performance GaN MMICs and mixed signal GaN circuits. Our GaN fabrication capability includes device epitaxial layer growth by MBE with state-of-the-art material uniformity of better than 1 percent across 4-inch diameter wafers, electron-beam gate lithography for typical gate lengths down to 0.15 micrometer, state-of-the-art back side process with wafer thinning to a thickness of 50 micrometers and fabrication of through-substrate-vias on silicon carbide substrates. Our GaN HEMT process is high-yield, low-cost and easily scalable to a larger capacity. HRL delivered the largest number of fully processed and tested GaN wafers of all participants in the DARPA Wide BandGap Semiconductor (WBGS) Phase I program. Our current material growth and fabrication capabilities can meet the current and near-term system needs for all but the highest commercial volumes.

We have demonstrated a variety of significant achievements in GaN MMICs including a 33-GHz microstrip power amplifier MMIC (2.8 watts of RF output power with 27 percent power-added efficiency) and a robust 2 GHz to 12 GHz low-noise MMIC (consumes only 15 milliwatts of DC power and survives 40 watts of peak RF input power without protection circuitry). The low-noise MMIC amplifiers (LNAs) are more robust than those of our competitors and consume less DC power. HRL's discrete transistors have demonstrated continuous wave output power densities of 7.4 watts per millimeter with associated power added efficiency (PAE) of 40 percent at a frequency of 30 GHz – the best combination of power and PAE reported at this frequency. HRL's power transistors showed almost no degradation of continuous wave (10 GHz) output power and PAE after 400 hours continuous RF stress at 30-volt drain bias.

We continued to advance our high temperature GaN IC process (Figure 5) with the recent demonstration of enhancement-mode transistors that facilitate control circuits with normally off operation. This is not only important for low power consumption but also for fault tolerance of critical control circuitry.


HRL has developed unique capabilities for antennas and other electromagnetic structures that are not available elsewhere. Because of our broad technical diversity, HRL takes a non-traditional approach to electromagnetics problems, a technique that has resulted in novel solutions for a variety of important applications, many of which were considered difficult or impossible using conventional methods. HRL has specific expertise in compact and conformal antennas, vehicle/antenna integration, simplified diversity schemes for mobile communications, low-cost beam steering techniques, broadband conformal antennas, and novel power-combining methods. A primary focus of our work has been low-cost, lightweight, conformal, and hidden antennas – areas that have become increasingly important in recent years.

We have made significant investments in tools for solving problems in antennas and electromagnetics. These devices include software tools, including commercial codes such as HFSS, FEKO, XFDTD, and IE3D, as well as our own codes that we have developed in-house, such as FastScat, which uses advanced techniques to solve large problems, and can be customized for specific requirements. We also have a variety of measurement facilities, including both a far-field chamber and a near-field chamber, and several network analyzers that are capable of measuring from UHF to millimeter wave frequencies (Figure 6).



Finally, complementing HRL's microwave MMIC capability, high speed mixed signal IC capability, and novel antennas, we are developing miniature micro-machined tunable filters compatible with common wafer-scale processing techniques. Simulations of these devices suggest their potential capability to span frequencies ranging from 4 to 20 GHz. Initial demonstrations at fixed frequencies have substantiated the models and designs. Long-range objectives for these filters will be to integrate them with the other microwave technologies, mentioned above, to produce truly reconfigurable RF front-ends.

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