5G • 5G-Advanced (Rel-18)
RF Circulators in SBFD
Ferrite and Magnetic-Free Circulators for Shared Antenna Duplexing
Three-port non-reciprocal RF devices that direct transmit power to the antenna array while routing received signals to the LNA, providing first-stage isolation.
Technical Explanation
When a single antenna array is shared for both transmitting DL sub-bands and receiving UL sub-bands, an RF circulator routes signals based on propagation direction: transmit signals from port 1 flow exclusively to antenna port 2, while received signals from port 2 flow exclusively to receiver port 3, delivering 20 to 30 dB of essential front-end hardware isolation.
Key Functions
- Provides 20 to 30 dB of non-reciprocal physical hardware isolation on shared antennas
- Protects sensitive receiver amplifiers from direct high-power transmitter energy
- Explores silicon-integrated magnetic-free circulators to reduce weight and cost in base stations
- Forms the foundational first stage of the multi-tier self-interference cancellation chain
Specifications
3GPP TR 38.858 (Rel-18)
Interfaces
gNodeB Antenna Feed
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