RF Receiver Protection Circuit for High-Power LNA Isolation
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Solution Overview
Problem
Modern RF receivers with low-voltage components are susceptible to damage from high power RF signals, particularly due to blocker signals exceeding allowed input levels, which conventional protection methods fail to adequately address, often requiring costly and complex circuit modifications.
Innovation Solution
Integrating a power detector circuit with an RF switch in the transceiver to measure signal power at the antenna interface, controlling the switch to decouple the antenna from the LNA when high power signals are detected, and sending notifications to reduce gain, thereby preventing signal damage with minimal circuit alteration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional protection methods are used to protect RF receivers from high power signals, then receiver reliability is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines the power detection function and RF switching function into a single integrated circuit block. The power detector circuit is directly coupled to the RF switch, eliminating the need for separate protection circuits and reducing overall system complexity while maintaining reliable protection against high power signals.
Solution Approach 2:
The RF switch serves dual functions: normal RF signal routing and protection switching. By making the switch multi-functional, the patent eliminates the need for dedicated protection circuitry, thereby reducing device complexity and manufacturing cost while maintaining receiver reliability.
2Reliability
If low-voltage process components are used to improve noise performance and reduce current consumption, then receiver sensitivity is improved, but susceptibility to damage from high power signals increases
Solution Approach 1:
The power detector circuit continuously monitors the input signal power level before the signal reaches the LNA. When high power is detected, the protection switch opens in advance to prevent the harmful signal from reaching the sensitive low-voltage components, thus preserving both the noise performance and protecting against damage.
Solution Approach 2:
The RF switch acts as an intermediary between the antenna interface and the LNA. It mediates the signal path by allowing normal signals to pass through to the low-voltage components while blocking high power signals, thus protecting the sensitive components without affecting their noise performance.
3Reliability
If an RF switch is integrated with a power detector circuit to prevent damage from high power signals, then protection effectiveness is improved, but circuit complexity increases
Solution Approach 1:
The patent merges the power detector circuit and RF switch into a single integrated unit with direct coupling. This combination provides effective protection while minimizing the increase in circuit complexity by eliminating separate protection circuitry and interconnections.
Data Source
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AI summary
Methods and apparatus for preventing damage to a radio frequency (RF) receiver are disclosed. An example RF protection circuit forms part of an RF receiver and includes an antenna interface configured to receive an RF signal from an antenna, an excess power detection circuit coupled to the antenna interface, the excess power detection circuit configured to compare a power of the RF signal to a threshold power level, and an RF switch coupled between the antenna interface and an input terminal of a low-noise amplifier (LNA), the RF switch configured to decouple the antenna interface from the input terminal of the LNA in response to the excess power detection circuit determining that the power of the RF signal exceeds the threshold power level.