This article discusses the importance of satellite communication payloads for modern space missions.
It also features the products from Texas Instruments and their applications for the NewSpace missions.
The article is developed in collaboration with Texas Instruments, a paying participant in the satsearch membership program.
Introduction
The satellite communications industry is experiencing a significant transformation, driven by the relentless pursuit of innovation and the increasing demands of today’s data-driven world. As satellite technology evolves, so do the subsystems and payloads that enable high-performing satellite communications. New Space companies are at the forefront of this evolution, harnessing cutting-edge technologies to unlock new opportunities in areas such as phased array antennas, quantum key distribution or laser communication systems. In this article, we will delve into the growing demand for high-performing satellite communications payloads and the critical technical systems required to support them.
Antenna technology and RF signal chain
In the rapidly evolving landscape of satellite communications, the changes observed in antenna technology and the RF signal chain have been nothing short of remarkable. Over the past two decades, several key transformations have taken place, primarily driven by the increasing demand for higher data rates and the ability to handle multiple channels or users concurrently. One of the pivotal factors influencing this evolution has been the significant reduction in launch costs, making Low Earth Orbit (LEO) constellations an increasingly attractive option.
One notable shift has been the adoption of RF sampling. RF sampling, in essence, involves the direct sampling of RF signals, thereby eliminating the need for intermediate frequency stages and simplifying satellite architecture. This approach has necessitated the development of very high-speed data converters and powerful Field-Programmable Gate Arrays (FPGAs). Furthermore, RF sampling has extended to high-frequency bands, such as X-Band (8-12GHz), with substantial instantaneous bandwidths of several gigahertz. This exponential increase in sample data has driven the development of next-generation FPGAs to handle the immense data processing requirements.
Facilitating multiple end-points in satellite communication presents a formidable challenge, demanding the integration of increased intelligence and processing power to ensure efficient data routing. In the realm of Low Earth Orbit (LEO) constellations, where satellites swiftly orbit the earth’s surface, the need for rapid antenna repositioning and seamless satellite-to-satellite transitions adds another layer of complexity. To navigate these intricacies, phased array antennas, known as electronically steered antennas, have emerged as a crucial solution, harnessing the benefits of beamforming technology.
Electronically steered antennas offer the advantage of swiftly adjusting the antenna beam, facilitating multi-beam connections to multiple end-points, and achieving a higher degree of focus in antenna beam alignment. However, as the number of elements in phased array antennas increases, so does the complexity of electronic design and the associated thermal management challenges. Furthermore, the demand for smaller cell phone antennas in space necessitates even higher antenna gain factors and an even greater number of elements per user in the phased array antenna. Transmitting high-speed data to each cell phone also requires a substantial amount of radiation power.
In summary, RF designers for satellite communication are witnessing a continual increase in sampling rates and the number of elements in phased array antennas, all while the board area per element decreases. This places a premium on electronic components that can deliver high power density, high efficiency and occupy minimal board space. Texas Instruments (TI) has been at the forefront of addressing these evolving needs with a strong focus on very high-speed data converters, high-frequency clocking solutions of exceptional quality, and the integration of functions to enhance overall performance. An example of this integration is the Fully differential Amplifier (FDA) TRF0206-SP, which replaces bulky baluns and gain blocks with RF amplifiers of even better linearity.
Mastering the power design challenges
The latest power supply and power generation capabilities in satellite communications systems are evolving in response to the increasing demand for high-performance Field-Programmable Gate Arrays (FPGAs) and the associated data processing requirements. FPGAs are becoming a cornerstone of these systems due to their ability to handle vast amounts of data and interface with RF-sampling Analog-to-Digital Converters (ADCs), Digital-to-Analog Converters (DACs), and Analog Front Ends (AFEs). However, these advanced FPGAs are notably power-hungry, with some of the latest models, like the Xilinx (AMD) Versal FPGA, consuming up to 100W at the core supply, while simultaneously operating at lower core voltages, such as 0.8V. These specifications place immense pressure on power supply designs.
To meet these challenging power requirements, TI offers a range of solutions tailored to the radiation-hardened demands of satellite systems. This includes rad-hard controllers like the TPS7H5001-SP and rad-hard Gallium Nitride (GaN) FET driver TPS7H6003-SP, designed to support the rigorous needs of high-performance FPGAs. For other power rails in the system, lower current Point-of-Load (POL) regulators and Low Dropout Regulators (LDOs) can be employed. TI’s offerings include the TPS7H4002-SP, supporting up to 3A, and the TPS50601A-SP, with a current capability of 6A. Additionally, for applications requiring high Power Supply Rejection Ratio (PSRR), TI’s RF-LDO TPS7H1111-SP provides exceptional PSRR, while alternatives like TPS7H1101A-SP (3A) and TPS7A4501-SP (1.5A) cater to varying needs.
Developing efficient and reliable power solutions for the latest FPGAs is a complex task, which TI is addressing with a wide range of solutions for different radiation hardness requirements. The availability of samples, evaluation modules (EVMs), dummy packages, and comprehensive collateral materials such as application notes, reference designs, and simulation models (PSpice and Simplis) further facilitates the design process.
Innovations for satellite communication payload design
TI is offering a range of products that have been and are instrumental in pushing the boundaries of the space industry. The LMX2615-SP, for instance, is a wideband synthesizer with phase synchronization and JESD204B support, with a figure of merit of -236 dBc/Hz, signifying remarkably low in-band noise and jitter performance. Complementing this, TI provides the ultra-low noise LDO, TPS7H1111-SP, which limits power supply-generated phase noise and clock jitter to an ideal extent.
TI’s focus on achieving the highest power density in the industry for DC/DC conversion is exemplified by the TPS7H4001-SP, which can double the power density compared to its closest competitor, addressing the power demands of space systems effectively. Furthermore, TI empowers the use of Gallium Nitride (GaN) technology in space applications through advanced gate drivers and PWM controllers, enhancing efficiency and performance.
In the high-speed data conversion domain, TI offers the ADC12DJ5200-SP, a radiation-hardness-assured (RHA) 12-bit ADC with dual 5.2-GSPS or single 10.4-GSPS capabilities, meeting the stringent requirements of space applications. The AFE7950, a 4-transmit, 6-receive RF-sampling transceiver, provides versatile RF capabilities for space systems, covering frequencies up to 12 GHz with a maximum 1.2 GHz instantaneous bandwidth.
Integration is a key facet of TI’s innovation. The company recognizes the importance of generating accurate biasing voltage for solid-state power amplifiers, offering highly integrated solutions like the AFE11612-SEP, which combines 16 ADCs, 12 DACs, temperature sensors, and GPIOs, streamlining satellite subsystems.
Moreover, TI has contributed significantly to the adoption of plastic packaging for space applications, garnering approval from the Defense Logistics Agency (DLA) for the QMLP standard. Plastic packages offer advantages in terms of smaller footprint, compatibility with LEO constellations, lower mechanical stress, and ease of integration, while maintaining radiation hardness. This innovation facilitates a cost-effective approach to space missions without compromising performance.
In summary, TI’s areas of innovation span across various dimensions, including efficiency and power density in the power supply domain, ultra-low noise, extremely high-speed data conversion, low-jitter GHz clocking solutions, integration of self-diagnostics, and advancements in packaging technologies.
Optical inter-satellite communication
The emergence of New Space has opened up exciting possibilities in market verticals such as laser communications, ushering in a new era of high-performance electronic component requirements. Laser communication, as compared to traditional radio communication, places significantly greater demands on precision in transmitter and receiver pointing. To achieve the level of precision needed, precise motor control systems are essential, and Texas Instruments offers the TMS570LC4357-SEP, a space-grade lock-step MCU operating at 300MHz with specific features tailored for precision motor control applications. For motor control accuracy, measuring the current in each phase of the motor is crucial, and TI’s rad-tolerant current shunt monitor, INA240-SEP, with an exceptionally wide common-mode voltage range from -4 up to 80V and its unique capability of PWM rejection, proves invaluable in this regard.
In the context of laser communication receivers, the requirements extend to higher-speed data converters and clocking products that enable increased modulation density. TI offers solutions such as the ADC12DJ5200-SP, an RF sampling ADC supporting input frequencies up to 10GHz, and the AFE7950, a multi-channel transceiver featuring six RF-sampling ADCs. Clocking solutions are also paramount, and TI provides options like the LMX2694-SEP, a 15GHz synthesizer, and the LMK04832-SEP, a high-performance clock conditioner with 14 outputs. As the laser communication market continues to evolve and expand, Texas Instruments remains committed to delivering the cutting-edge electronic components required to drive the performance and precision demanded by this emerging vertical.
Rapid product development and employment
Europe’s flagship connectivity program, Infrastructure for Resilience, Interconnectivity and Security by Satellite (IRIS2), has taken a significant leap in embracing Quantum Key Distribution (QKD) capabilities, reflecting the growing importance of laser communication in high-security demand markets, particularly in the realms of defense and intelligence. In the pursuit of enhanced security, it is imperative to stay ahead of competitors and potential threats from hackers. This necessitates the rapid deployment of the latest technology and continuous updates to maintain an edge.
To support such fast development cycles, a “catalogue business approach” becomes paramount, offering readily available space-qualified parts with complete documentation and quality reports. This approach, coupled with published inventory and pricing and sample delivery from an online store within days, expedites the decision and procurement process significantly. Additionally, robust technical support, including TI‘s E2E Forum, ensures that the most cutting-edge solutions can be swiftly integrated into high-security satellite systems.
Furthermore, the adoption of plastic packages compliant to the Defence Logistics Agency’s QMLP (Qualified Manufacturers List – P) standard plays a pivotal role, offering a much faster turnaround to transform commercial devices into space-grade components. This approach streamlines the development process and allows for rapid adaptation of the newest technologies, aligning with the dynamic demands of the high-security market segments served by constellations such as IRIS2.
Future outlook
The next level of evolution in satellite communications holds both opportunities and challenges for satellite manufacturers and integrators. RF sampling at higher frequencies, such as K or Ka band, is expected to simplify the RF front-end architecture, yet it introduces new complexities in high-speed clocking and data processing. The increasing demand for beamforming will lead to a greater number of elements in antenna systems, necessitating more channels for data converters. Additionally, declining launch costs will facilitate larger satellite constellations, offering enhanced system-level resiliency through redundancy.
Inter-satellite communication, connecting nanosatellites and smallsats to backbone systems like IRIS2 and onward to Earth, will play a pivotal role in the future. The semiconductor industry has to rapidly respond to these market shifts, particularly in New Space projects, to enable customers to build communication systems with the latest technology, including critical security aspects.
However, several risks loom on the horizon. Balancing cost and durability becomes crucial in the context of lower launch costs and the move to higher number of satellites. Thermal management poses another challenge as electronic capabilities increase, demanding efficient heat dissipation solutions. Predictability of development time remains a key concern, emphasizing the importance of a catalog approach that offers reliability and speed. TI is poised to address these opportunities and risks. With a commitment to releasing more devices per year and innovations across multiple dimensions, TI offers a catalog business model that ensures project completion predictability and a reliable supply chain. TI‘s strong technical support, encompassing reference designs, application notes, and forums like E2E, equip customers with the resources they need to navigate the evolving landscape of satellite communications.
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