Multiband Transceiver Feedback Path Isolation by Crosstalk Cancellation
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Solution Overview
Problem
Multiband transceivers face challenges in canceling cross-talk between adjacent transmit paths, leading to deteriorated performance due to insufficient RF/IF path isolation, which complicates compensation of transmitter impairments and noise, especially in tightly packed devices with shared components.
Innovation Solution
A cross-talk canceller is implemented within the multiband transceiver to estimate and cancel interference between feedback paths using known signal estimation techniques, such as Least Squares estimation, allowing for effective compensation of transmitter noise and improving overall performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If transmit paths are closely spaced in a multiband transceiver, then device integration is improved and space is saved, but cross-talk between adjacent feedback paths increases and performance deteriorates
Solution Approach 1:
A cross-talk canceller is introduced as an intermediary component between the closely spaced transmit paths. The canceller estimates cross-talk signals using known reference signals and subtracts these estimates from the received signals, thereby eliminating the harmful interference while allowing the transmit paths to remain closely spaced for compact integration
Solution Approach 2:
The system employs feedback mechanisms where a portion of the transmitted signal is fed back through the same path to serve as a reference. This reference signal is used by the cross-talk canceller to estimate and remove cross-talk contributions from adjacent paths, enabling the system to compensate for the interference caused by close spacing
2Object-affected harmful factors
If RF/IF path isolation is increased to reduce cross-talk, then signal quality is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces physical isolation mechanisms (such as shielding, filtering, and spatial separation) with a signal processing approach. The cross-talk canceller uses digital signal processing to estimate and remove cross-talk, substituting complex mechanical/isolation structures with algorithmic solutions that achieve the same interference reduction goal
3Reliability
If cross-talk compensation is implemented, then TX noise performance is improved, but computational complexity and processing requirements increase
Solution Approach 1:
The cross-talk canceller implements partial compensation by focusing on the dominant cross-talk paths rather than attempting to compensate for all possible interference sources. The system estimates and removes the most significant cross-talk contributions, achieving substantial performance improvement without the full computational burden of complete compensation
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
Embodiments relate to a multiband transceiver apparatus (100), comprising a first transmit path (110) operable to transmit a first transmit signal (sig1) in a first radio frequency band (RF1), wherein the first transmit path (110) comprises an input (112), an output (114) and a first feedback path (116) from the output towards the input of the first transmit path, a second transmit path (130) operable to transmit a second signal (sig2) in a second radio frequency band (RF2), the second radio frequency band (RF2) being different from the first radio frequency band (RF1), wherein the second transmit path (130) comprises an input (132), an output (134) and a second feedback path (136) from the output towards the input of the second transmit path, and a cross-talk canceller (150) operable to cancel cross-talk from the second feedback path (136) to the first feedback path (116) and/or to cancel cross-talk from the first feedback path (116) to the second feedback path (136) of the multiband transceiver apparatus (100)