CMOS RF/mmWave Technologies Enable the Transformation of IoT Satellite Communications

SATCOM 

Cormac O'Sullivan - S3semi

Aug 31, 2018

The ongoing and predicted explosive growth in IoT is placing ever increasing demands on connectivity – a recent report by Ericsson predicts that there will be over 20 billion connected things in use globally by 2020. IoT networks rely primarily on Wi-Fi, LTE and, soon, 5G technologies, but satellite communications play an increasingly vital role in “filling in” gaps in coverage, complementing wireless networks to enable seamless global coverage.

Whereas satellite connectivity for IoT applications has traditionally been L-band at 1 -2 GHz, developments in Ku/Ka-band and beyond are promising to deliver a satellite superhighway. 

The pressure is now on satellite operators to enable easier and lower-cost access to satellite networks – i.e. smaller and low-cost terminals with traditional dishes being replaced by lower profile, “flat panel” antennas. Recent advances in CMOS technology, with transistors becoming smaller and faster, have now made it the most attractive option for mmWave circuits, due its low cost, low power consumption and high levels of integration – including the ability to integrate analog and digital circuits on the same chip.

In this article, we look at some of the factors that are enabling this evolution in satellite communication and discuss how Dublin-based S3semi’s offering of RF IP and custom ASICs using standard CMOS can be deployed in small-size, low-cost solutions.

Overview of developments in satellite communications 

A number of IoT-based developments are transforming the economics of satellite production and launch, making access to satellite communications feasible for a wider range of IoT applications.


CubeSats, initially conceived in 1999, have moved out of the university research domain and into the commercial arena. The reference CubeSat is based on a 10cm cube and the design has been facilitated by the ongoing miniaturization of the on-board electronics. The low mass, (can be less than 1.33Kg), of CubeSats significantly reduces launch costs and the satellites often share a launch vehicle with larger satellites. Although CubeSats are beginning to be deployed in deep-space exploration, they are typically used in low-earth orbit (LEO) for IoT applications, including remote sensing or communications, using the lower frequency end of the satellite spectrum, such as L band. The wider nanosat classification applies to the grouping of small satellites up to 500 Kg in mass and, according to nanosat.eu, more than 1800 CubeSats and nanosats have been launched since the technology was first deployed.

The insatiable demand for bandwidth on the move, driven by applications such as the connected car, AI & augmented reality, is further transforming satellite communications. Investors cash is following this opportunity with significant amounts of capital flowing into the industry to fund the delivery of High Throughput Satellite (HTS) services and a broadband superhighway in space.

Two organizations are forcing the pace, with OneWeb changing the economics of satellite production and deployment and SpaceX driving down launch and space services costs.

In Q4 2018, OneWeb plans to launch the first satellites in its new LEO constellation, operating in the Ku band with user terminals based on phased-array antenna. The user antenna will measure approximately 36 by 16 centimeter and will provide Internet access at 50 megabits/second. 

A number of OneWeb’s competitors have equally ambitious plans, including SpaceX which has received FCC approval to launch and operate a constellation of 4,425 satellites using Ka-Band (20 and 30 GHz) and Ku-Band (11 and 14 GHz) links.

SpaceX has also emerged as an industry front-runner in launch and spaceflight services, significantly reducing rocket launch costs and, spurring competition with other providers such as Europe’s Arianespace and US launch services provider, United launch Alliance. 

The combination of lower launch costs and smaller, cheaper satellites resulting from these market disruptions, is playing a huge role in opening up HTS to the mass market. However, whilst these developments are creating more bandwidth in the space segment, cost of access remains a barrier, both to mass market adoption and also to the specific requirements of IoT applications. Terminal size and cost is key to enabling satellite operators and service providers to maximize their opportunity in this rapidly developing market. IoT applications demand low cost, low power consumption, high network capacity and long range, putting pressure on the cost and complexity of the silicon required to connect objects.

Developments in Satellite Terminals

The higher, Millimetre Wave (mmWave), frequencies of Ku and Ka band enable smaller antenna size, making phased-array antenna systems practical, but also bring challenges in the design of the RF transceiver, the key component of the satellite terminal. In the past, mmWave circuits were based on III-V compound semiconductors, such as GaAs, due to the superior noise characteristics and power-handling capabilities at high frequencies they achieved at the time. This is no longer true however, with superior performance now being achieved by the very cost-effective 55nm CMOS technology. Additionally, with the most advanced III-V technologies at 150nm, CMOS at 55nm supports a higher level of on-chip integration, with 28/22nm being even better.

Although physical constraints and economic considerations signal that its days are numbered, ongoing huge investments in semiconductor fabrication plants, (fabs) continue to drive semiconductor evolution in-line with Moore’s Law. The resultant scaling of CMOS transistors for density and performance has yielded high transition frequencies (Ft) as an important by-product. With transistors becoming not only smaller but also faster, CMOS is now today’s most attractive option for mmWave circuits, with its low cost, low power consumption and high levels of integration – including the ability to integrate analog and digital circuits on the same chip.

Despite these advances in and advantages of CMOS technology, the design of a mmWave CMOS transceiver exhibits the normal RF challenges, such as intermodulation products resulting from distortion, noise and the effects of layout parasitic elements. RF SoC production, therefore, requires specialist skills and experience in CMOS design and fabrication techniques in order to successfully produce mixed-signal designs, integrated on the same chip. 

S3semi has over 20 years of experience in this field, with in-house design capabilities spanning VHF up to mmWave technologies. Their wide-ranging IP portfolio covers all of the main RF transceiver building blocks such as LNA (low-noise amplifiers), Mixers, VCOs (Voltage Controlled Oscillators), Synthesisers/PLLs and ADCs and DACs, (Analog to Digital and Digital to Analog Converters) capable of operating at Gsps, (Gigasamples per second). 


Figure 1: S3semi IP Portfolio

In developing this portfolio, S3semi have built significant expertize in the use of Digitally Assisted Analogue (DAA) techniques, a key enabler of mixed-signal integration, where digital logic monitors analog circuit performance and adjusts analog circuit parameters using calibration loops. 

Case studies using S3 Semiconductors portfolio and expertise

S3semi’s growing list of customer projects in the satellite space have demonstrated their ability to:

  • produce reduced footprint -physically smaller terminals / modems
  • reduce bill of materials -up to 80% depending on system architecture
  • achieve significant cost saving versus existing hardware 
  • reduce power consumption -critical in battery, mobile & solar power applications
  • support HTS and advanced beamforming topologies
  • support high performance data services  

S3semi has recently developed and supplied a custom dual-band transceiver ASIC, to a leading global provider of IoT communications solutions. The device will enable customers to remotely track, monitor and control fixed and mobile assets in multiple markets from industrial, to oil and gas, to transportation. The S3 Semiconductors M2M ASIC platform provides an integrated solution that will sense an asset’s environment, control it and regardless of where it is located in the world, connect to it, allowing customers to maintain, optimize and protect the value of their assets.

In October 2017 S3semi was commissioned to work on the research and development of new transceiver technology as part of a programme jointly funded by the European Space Agency, (ESA), and a leading mobile satellite communications services operator. S3semi will develop the architecture which will realize the small form factor, low -power solutions underpinning the delivery of future innovative mobile satellite communication services.

S3semi have a long-standing relationship and history of innovation with Iridium, a provider of global satellite communications.  NEXT is Iridium’s 2nd generation satellite service, aimed at the IoT market and the NEXT system is based on a fully integrated, single-conversion radio transceiver together with a digital baseband processor SoC, designed and delivered by S3semi. When developed, the transceiver, represented a radical innovation from the dual conversion architectures, common in the Mobile Satellite Services space. This device enabled production of the smallest and lightest satellite modems in the world, as a result of which Iridium was able to substantially reduce the form factor, power consumption and cost of their terminals. The NEXT transceiver followed a previous generation chipset, delivered by S3semi for the Iridium 9602 Modem. 

The above projects demonstrate S3semi’s ability to deploy a multi-disciplined team of engineers with expertise in System design, RF, analog and digital design as well as the company’s leading-edge RF and mixed-signal IP portfolio. This capability, combined with program management expertise, enables S3semi’s customers, such as Iridium and others, to stay at the forefront of the growing IoT Satellite Market.

Conclusion

Significant investment in the satellite industry over the last 5 years has changed the economics of satellite construction and launch. This activity is transforming satellite communications, with several new constellations promising to deliver high throughput communications on a global scale.

Demands on satellite operators have now shifted to access costs, with size, power consumption and cost being critical factors in satellite terminal and antenna design. CMOS RF/mmWave technologies are key enablers of the RF devices which are at the heart of a new generation of small and low-cost terminals. 

S3semi has a long history of designing, producing and delivering low cost, mixed-signal CMOS mmWave RF chips with up to 80% reduction in BoM. In addition to delivering innovative designs, S3semi manages every aspect of supplying production devices to its customers using some of the world’s most advanced semiconductor production facilities. 

The company is well placed to support customers with optimizing designs whilst achieving a low cost of ownership and high returns on investment not thought possible with custom chips designs until now.

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