RFUnderstanding RF Front Ends: Architecture, Components, and 5G Applications
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The RF (Radio Frequency) front end refers to the components and circuitry located at the input of an 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.
- Transmit Part: Performs tasks such as signal processing, modulation, frequency up conversion, filtering, amplification (using power amplifier) and signal transmission.
- Receive Part: Performs tasks such as signal reception, amplification (using low noise amplifier), filtering, frequency down conversion, demodulation and preliminary signal processing.
An RF front end typically consists of several key components such as an 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 an RF front end (RFE) varies 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). A 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’s take a brief overview of each:
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Integrated Front End (iFEM): This architecture integrates multiple RF components and functions into a single module. It allows reduction in size and complexity and offers improvement in performance.
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Discrete Front End (dFEM): 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.
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System-on-Chip (SoC): This architecture integrates RF front end (RFE) components, digital processing, baseband processing and other functions onto a single chip.
A 5G RF front end should support the following features to work satisfactorily in a 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 a 5G front end. Following are the key 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 an American semiconductor company which designs and develops RF systems and solutions for wireless and broadband communications. It was founded in 2015 by the 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. Their website is: www.qorvo.com .
Conclusion
Overall, the 5G RF front end is a complex and versatile component which plays a crucial role in enabling high speed, low latency, and reliable communication capabilities.
