Duplexer Circuit Phase Cancellation for RF Leakage Isolation
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Solution Overview
Problem
Radio frequency (RF) communication systems face challenges in effectively canceling signal leakage between transmit and receive paths, which affects performance and isolation in FDD and TDD radio front-ends, especially in 5G technologies with tight duplex spacing and high power levels.
Innovation Solution
A duplexer circuit design that includes phase shifters and matched duplexers to coherently sum and destructively cancel RF signals, using a configuration of transmit and receive path splitters with phase shifts to create parallel isolation paths that cancel leakage without altering the duplexers' construction, thereby enhancing isolation between transmit and receive paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional duplexer circuits are used with tight duplex spacing, then frequency utilization is improved, but signal leakage between transmit and receive paths increases
Solution Approach 1:
The transmit path is divided into two separate parallel paths, each with its own duplexer. This segmentation allows independent control and phase manipulation of each path, enabling destructive interference of leakage signals while maintaining the benefits of tight duplex spacing for frequency utilization.
Solution Approach 2:
Phase shifters are introduced in each parallel path to create opposite phase relationships between the two paths. The leakage signals from each path are made 180 degrees out of phase, causing them to cancel each other through destructive interference, effectively counteracting the harmful leakage effect.
2Object-generated harmful factors
If isolation between transmit and receive paths is increased, then signal leakage is reduced, but device complexity increases
Solution Approach 1:
Two parallel paths with duplexers and phase shifters are merged at the combine node, where their leakage signals destructively interfere. This merging approach achieves high isolation through coherent cancellation rather than requiring complex filtering or shielding in each individual path.
Solution Approach 2:
Phase shifters are used to dynamically adjust the phase parameters of signals in each path. By changing the phase parameter to maintain 180-degree opposition between paths, the system achieves adaptive leakage cancellation that responds to varying operating conditions without increasing structural complexity.
3Object-generated harmful factors
If phase shifters and parallel paths are added to cancel leakage, then signal leakage cancellation is improved, but insertion loss increases
Solution Approach 1:
The circuit converts the potentially harmful leakage signals into a beneficial effect by using them for destructive interference. The same parallel paths that carry desired signals also carry leakage signals that are made to cancel each other, turning a harmful byproduct into a mechanism for improved isolation without requiring additional lossy filtering elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces RF leakage between transmit and receive paths, improving reference sensitivity and relaxing filter requirements, while maintaining low insertion loss and cost-effectiveness, even in scenarios with small duplex spacing.
Implementation Method 1
applying a first phase shift to the first radio frequency transmit signal between the power amplifier and a first duplexer on the first transmit path; applying a second phase shift to the first radio frequency receive signal between the antenna and a second duplexer on the first receive path; and applying a third phase shift to the second radio frequency receive signal between the first duplexer and the receive splitter on the second receive path
Implementation Method 2
the receive path splitter configured to coherently sum the pair of radio frequency receive signals
Implementation Method 3
the receive path splitter further configured to destructively cancel leakage of the pair of radio frequency transmit signals through the first and second duplexers
Data Source
AI summary
Systems and methods for duplexer circuits having signal leakage cancellation are provided. In one aspect, a duplexer circuit includes a transmit path splitter configured to split a radio frequency transmit signal into a pair of radio frequency transmit signals, and a receive path splitter configured to combine a pair of radio frequency receive signals. The duplexer circuit also includes an antenna path splitter configured to combine a pair of radio frequency transmit signals and split a radio frequency receive signal into the pair of radio frequency receive signals, and first and second duplexers. The first duplexer is coupled to a first leg of each of the transmit path splitter, the receive path splitter, and the antenna path splitter, and the second duplexer is coupled to a second leg of each of the transmit path splitter, the receive path splitter, and the antenna path splitter.