Upstream Injection for Transmitter Leakage Cancellation
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Solution Overview
Problem
Existing active cancellation methods for transmitter leakage in radio receivers increase power consumption and introduce noise in the receive frequency band due to the limitations of directional couplers and non-linear components.
Innovation Solution
Injecting a transmitter leakage cancellation signal in the upstream direction through the receive path, where the noise component is attenuated or passed through the antenna, and the desired component is reflected to cancel the leakage, minimizing sensitivity degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active cancellation is implemented using a directional coupler to generate RF cancellation signal, then transmitter leakage is reduced, but power consumption increases and noise is introduced in the RX frequency band
Solution Approach 1:
Instead of generating cancellation signal in the forward direction through a directional coupler, the patent applies inversion by injecting the cancellation signal in the reverse (upstream) direction through the receive path. This allows the signal to traverse the receive path components in reverse order, causing noise components to be attenuated by upstream filters rather than amplified, thereby reducing both power consumption and noise while maintaining leakage cancellation effectiveness.
Solution Approach 2:
The patent introduces an intermediary mechanism by using the receive path itself as the transmission medium for the cancellation signal. Rather than using a separate forward-path coupler, the receive path components (filters, amplifiers, etc.) serve as intermediaries to deliver the cancellation signal to the combiner, where it can effectively reduce transmitter leakage without introducing additional noise.
2Object-affected harmful factors
If active cancellation is implemented using a directional coupler to generate RF cancellation signal, then transmitter leakage is reduced, but noise in the RX frequency band increases
Solution Approach 1:
The patent reverses the injection direction so that the cancellation signal travels upstream through the receive path. This causes noise components generated by non-linear components to be attenuated by upstream filters before reaching the combiner, significantly reducing noise in the RX frequency band while maintaining effective leakage cancellation.
Solution Approach 2:
The patent converts the potentially harmful noise-generating non-linear components into beneficial elements by having them process the cancellation signal in reverse direction. The noise they would normally generate is instead attenuated by upstream filters, transforming these components from sources of harm into part of the noise-reduction mechanism.
3Object-affected harmful factors
If high output power is used in the auxiliary transmitter to overcome directional coupler coupling factor, then cancellation effectiveness is improved, but power consumption increases
Solution Approach 1:
By inverting the injection direction through the receive path, the patent eliminates the need for high output power to overcome coupler losses. The upstream path naturally provides the necessary signal levels through the existing receive path components, achieving effective cancellation without the power consumption penalty of high-power auxiliary transmitters.
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 approach reduces power consumption and noise in the receive frequency band, effectively canceling transmitter leakage while preserving receiver sensitivity.
Implementation Method 1
the desired component is reflected to cancel the leakage
Data Source
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Figure 3A
AI summary
Systems and methods are disclosed for active cancellation of transmitter leakage in a radio receiver that reduce power consumption and/or reduce noise in a desired receive frequency band. In some embodiments, in order to cancel transmitter leakage in a receive path, a cancellation signal is injected into the receive path in an upstream direction. By injecting the cancellation signal in the upstream direction, a noise component of the cancellation signal propagates through the receive path in the upstream direction and is either passed through a receive antenna or attenuated by an upstream component. Conversely, a desired component of the cancellation signal is reflected by an upstream filter and, thereafter, propagates through the receive path in the downstream direction to thereby cancel the transmitter leakage in the receive path. In this manner, active transmitter leakage cancellation can be performed while minimizing degradation of receiver sensitivity.