ST enhances SOI process for LTE front ends

ST - STHVDAC-304MF3 RF Front-End antenna-tuning circuitSTMicroelectronics has an SOI process which can deliver RF front end modules supporting the 40 different frequency bands required for LTE.

Called H9SOI_FEM, the process offers, says ST, ‘the industry’s best figure of merit for antenna switch and antenna tuning devices with Ron x Coff at 207fs[2].’

“The H9SOI_FEM dedicated process enables our customers to develop state of the art front-end modules that are half the size or smaller compared to today’s front-end solutions,” says ST’s Flavio Benetti, “Moreover, we have achieved a simplified process flow to enable extremely short overall lead-times and supply flexibility, which are crucial for end customers in this market.”

ST is now ready to start working with customers on new designs using H9SOI_FEM. Volume ramp-up is expected by the end of this year.

The H9SOI_FEM process is a 0.13µm technology with dual-gate 1.2V and 2.5V MOSFETs. Unlike conventional SOI processes, such as those used for discrete devices like RF switches, H9SOI_FEM supports multiple technologies such as GO1 MOS, GO2 MOS, and optimized NLDMOS. This allows H9SOI_FEM to support full monolithic integration of all key functions of an RF front end, which comprise RF switches, Low Noise Amplifier (LNA), multi-mode multi-band cellular Power Amplifiers (PAs), diplexers, RF coupling, antenna tuning and RF energy-management functions.

GO1 MOS is preferred for very-high-performance LNAs, capable of sustaining very low Noise Figure with 1.4dB @ 5GHz and providing threshold frequency (Ft) of 60GHz permitting 5GHz designs with safety margin.

In addition to GO2 CMOS, GO2 NMOS is widely used with RF switches and enables ST’s process to offer the industry’s best figure of merit for the antenna switch and antenna-tuning devices, with on-resistance x capacitance (Ron x Coff) of 207fs.

GO2 high-voltage MOS allows the integration of PA and energy-management functions. The optimized NLDMOS allows PAs to achieve Ft of 36GHz and efficiency of 60% at saturated low-band GSM power. For energy management, PLDMOS technology with 12V breakdown allows the device to be connected directly to the battery.

The performance of integrated passive components has also been optimized by depositing to three or four aluminum layers and also thick copper when needed.

H9SOI_FEM is suitable both for devices targeting the low end of the market, where low cost and extensive integration are crucial, as well as the high-end smartphone segment. High-end products typically require a combination of many frequency bands to support not only 2G, 3G and 4G standards, but also various other wireless connectivity standards such as Bluetooth, Wi-Fi, GPS and NFC (Near-Field Communication) for contactless payments.

[Image: ST - STHVDAC-304MF3, an example RF Front-End antenna-tuning circuit]

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