What is RF Front End (RFE) ?

The RF (Radio Frequency) front end refers to components and circuitry located at the input of RF system. This part of the system directly interacts with the incoming RF signal in the transceiver (Transmitter-Receiver). It ensures that the signal is properly amplified, filtered and converted to a suitable frequency range for subsequent processing.

At the transmit part, it performs tasks such as signal processing, modulation, frequency up conversion, filtering, amplification (using power amplifier) and signal transmission. At the receive part, it performs tasks such as signal reception, amplification (using low noise amplifier), filtering, frequency down conversion, demodulation and preliminary signal processing.

RF front end typically consists of several key components such as antenna, LNA (Low Noise Amplifier), RF filters, Frequency conversion mixer, Local Oscillator (LO), VGA (Variable Gain Amplifier), PLL (Phase Locked Loop), AGC (Automatic Gain Control) etc. The design of RF front end (RFE) vary as per desired specifications such as frequency range, power, modulation scheme and so on.

5G RF front end module architectures

Fifth generation (5G) wireless technology has been published in 3GPP release 15 and beyond. 5G wireless technology supports various frequency bands viz. sub 1 GHz, 1 to 6 GHz and above 6 GHz(millimeter wave frequencies). 5G Front End should support any one of these frequency bands. 5G uses high bandwidth (100 MHz per subcarrier) compare to LTE (20 MHz per subcarrier).

There are mainly three architectures used for 5G RF front end modules viz. Integrated Front End (iFEM), Discrete Front End (dFEM) and System-on-Chip (SoC). Let us understand overview of these architectures.
Integrated Front End : This architecture integrates multiple RF components and functions into a single module. It allows reduction in size and complexity and offers improvement in performance.
Discrete Front End : This architecture separates RF components into discrete modules. They are individually designed and assembled. It allows flexibility in design and optimization for specific use cases, but they are larger and complex compared to iFEM architecture.
System-on-Chip : This architecture integrates RF front end (RFE) components, digital processing, baseband processing and other functions onto a single chip.

5G RF Front End Module

5G RF front end should support following features to work satisfactorily in 5G network.
• It should support 5G frequency bands (Sub-6 GHz or mmwave).
• It should support massive bandwidth.
• It should employ advanced MIMO and beamforming techniques.
• It should support high data rates using advanced Modulation Schemes such as 256-QAM and higher.
• It should support multiple generations of cellular technologies such as 4G LTE, 5G NR and others.
• it should support power efficiency and linearity as per requirements.

Figure-1 depicts internal diagram of 5G RF Front End (5G RFE) components. RF front end mainly refers to LNA and PA modules used between antenna and RF transceiver. As shown RF front end consists of PA (Power Amplifier), LNA (Low Noise Amplifier), Tx/Rx Switch, Wideband filter etc. It is connected between 5G Transceiver and antenna.

Qorvo 5G RF Front End

The Qorvo device part number QM19000 is used as 5G front end. Following are the silent features of the device.
➤It supports 3.3 to 4.2 GHz frequency band.
➤It supports 4G and 5G waveforms (CP-OFDM and DFT-S-OFDM).
➤It supports ET (Envelope Tracking) and APT (Average Power Tracking) modes. Hence it delivers high linearity and high saturated efficiency.
➤It supports power class-2.
➤It occupies less space and hence other space can be used for 4x4 MIMO (downlink) and 2x MIMO (uplink) based components/devices.
➤It houses variable gain amplifier (VGA) to vary gain/attenuation requirements.

About Qorvo

Qorvo is american semiconductor company which designs and develops RF systems and solutions for wireless and broadband communications. It has been founded in 2015 by merger of TriQuint Semiconductor and RF Micro Devices. Qorvo Inc. develops core technologies and radio frequency (RF) solutions to mobile, infrastructure, defense/aerospace and Internet of Things markets. The company is headquartered in Greensboro, North Carolina. Refer website: www.qorvo.com.

Conclusion : Overall, 5G RF front end is a complex and versatile component which plays crucial role in enabling high speed, low latency and reliable communication capabilities.

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