Fabless semiconductor firm RFaxis Inc of Irvine, CA, USA, which designs RF semiconductors and embedded antenna solutions for wireless connectivity and cellular mobility, is unveiling a family of Nano RF products code named Nucleus.
The initial device, Nucleus45, is a fully integrated 5GHz 802.11ac RF front-end IC (RFeIC) in a 40nm CMOS process, scheduled for sampling to strategic customers in fourth-quarter 2014. A dual-band/dual-mode RFeIC in the same 40nm node, Nucleus4, will be available in Q1/2015. The firm will also introduce its next-generation Nucleus2 series products, providing a seamless migration from the 40nm to 28nm process node.
Driven by key applications such as smartphones, PCs/tablets, high-definition video streaming, and the Internet of Things (IoTs), Wi-Fi continues to enjoy huge market success, maintaining its explosive growth momentum, says RFaxis. According to market research firm Strategy Analytics, over 2 billion Wi-Fi chips were shipped in 2013, with annual shipment projected to exceed 3 billion units by 2017.
To further improve wireless speed and real-life data throughput, the Wi-Fi industry is rapidly adopting the latest IEEE standard, 802.11ac, which supports advanced modulation schemes such as 256QAM, up to 8x8 MIMO (multiple-in multiple-out) and MU-MIMO (multi-user MIMO), in order to deliver unprecedented high data speeds approaching 10Gbps. To further reduce size, enhance processor capability, and increase the level of integration, Wi-Fi system-on-chip (SoC) vendors have been constantly moving toward smaller CMOS process nodes for their next-generation products, says RFaxis.
As CMOS technology continues its migration path toward deeper-submicron nodes (such as 40nm, 32nm and 28nm), the reduction in supply voltage, along with passive losses associated with substrate leakage, poses great design challenges for radio-frequency power amplifiers (RF PAs) and front-ends with high-power capability, good linearity and competitive efficiency, says RFaxis. On the other hand, these nanometer-scale CMOS processes also provide new features and advantages, such as unprecedented signal processing power that can provide huge benefits to RF/analog designs if utilized properly.
For instance, DPD (digital pre-distortion) has been routinely used on existing mainstream Wi-Fi SoCs to help to deliver reasonable on-chip output power with good linearity for OFDM (orthogonal frequency-division multiplexing) modulation, while ET (envelope tracking) is rapidly emerging as a promising enabling technology for CMOS PAs to replace incumbent GaAs-based PAs for 3G/4G-LTE handset applications.
While these powerful digital techniques can be applied to control and enhance any type of RF front-end solution, the best synergy occurs when both the SoC (baseband/transceiver) and RF components are designed and fabricated in the same CMOS process, reckons RFaxis. That is the goal of the Nucleus product family. Due to its patented architecture, proprietary technology and in-house design expertise, RFaxis says that it has overcome technical hurdles and achieved high and linear RF power with low-voltage CMOS devices.
A prime example is RFaxis' RFX240, a 2.4GHz 11b/g/n/ac PA based on standard 0.18μm CMOS process, that delivers 26dBm (400mW) linear power with 3% error vector magnitude (EVM) for 64QAM OFMD at 5V supply voltage, with power-added efficiency (PAE) that surpasses that of competitor designs using GaAs or SiGe processes, it is claimed. RFaxis' portfolio of 2.4/5GHz RFeICs - complete with PA, LNA and antenna switches - have been in high-volume production as a result of low-cost CMOS process technology.
RFaxis says that, with the Nucleus product family, it will integrate high-performance RF in nanometer process nodes. Nucleus45 is designed to deliver 18dBm output power to meet the most stringent linearity requirement for 256QAM modulation for 11ac – without the use of any DPD techniques. The integrated LNA provides a low noise figure of 2.5dB at system level, with all losses associated with impedance matching and antenna switch included. The RF performance matches that with state-of-the-art designs from more expensive semiconductor processes such as GaAs, silicon germanium (SiGe) or silicon-on-insulator (SOI), it is claimed.
RFaxis says that the Nucleus solution provides the wireless industry with a path to synchronize robust RF, digital and mixed-signal designs in deeper-micron process nodes, enabling users to achieve their RF performance targets with accelerated design cycle, greatly reduced development risk and shortened time-to-market while avoiding massive new R&D investment.
"RF front-ends play a very critical role in maximizing the number of bars and guaranteeing the highest data rates for wireless communication devices such as smartphones and tablets," says chairman & CEO Mike Neshat. "Due to unique challenges in RF design, the wireless industry has been relying on expensive GaAs or SiGe technologies for their RF front-end requirements. RFaxis is the first and only company in the world that is shipping complete RF front-end solutions in pure CMOS process," he adds. "With the introduction of Nucleus, RFaxis is on solid track to fulfill its mission by offering the wireless industry an RF front-end solution that is native to CMOS and matches seamlessly with mainstream SoCs for Wi-Fi, ZigBee, Bluetooth, or Internet of Things."
