Adaptive Impedance Matching Receiver Circuit for Blocking Signal Isolation
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Solution Overview
Problem
Conventional RF receivers require peripheral discrete passive devices for impedance matching, which increase cost and limit bandwidth, and fail to effectively separate blocking signals from useful signals, leading to performance degradation and increased power consumption.
Innovation Solution
A receiving circuit with an active negative feedback structure, including a first amplification module, frequency mixing module, and second amplification module, which uses an active negative feedback low noise amplifier and a quadrature passive mixer to provide adaptive impedance matching across various bandwidths without additional passive devices or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discrete passive devices are used for impedance matching, then the matching circuit can be implemented, but the cost increases and the available operating bandwidth is limited
Solution Approach 1:
The patent extracts the impedance matching function from traditional discrete passive devices and implements it using an active negative feedback structure within the LNA circuit itself. This eliminates the need for external discrete passive devices while achieving broader bandwidth operation through the feedback mechanism that dynamically adjusts impedance matching across multiple frequency bands.
Solution Approach 2:
The LNA circuit is designed to perform multiple functions simultaneously: signal amplification, impedance matching, and frequency band adaptation. The active negative feedback structure enables the circuit to operate across wide bandwidths including multiple frequency bands (e.g., 700MHz, 800MHz, 900MHz, 1800MHz, 2100MHz, 2600MHz) without requiring separate matching circuits for each band, thus achieving multi-functionality.
2Device complexity
If a single-stage LC matching circuit is used, then the circuit complexity is reduced, but it cannot cover the required bandwidth ratio of 10%
Solution Approach 1:
The patent employs an active negative feedback structure where a portion of the output signal is fed back to the input through a feedback network. This feedback mechanism dynamically adjusts the input impedance to achieve matching across wide bandwidths. The feedback loop compensates for impedance variations across different frequency bands, enabling a single-stage circuit to cover bandwidth ratios exceeding 10% without increasing structural complexity.
3Adaptability or versatility
If a pi network or two-stage LC is used to increase bandwidth, then the bandwidth coverage is improved, but peripheral devices increase and noise increases, reducing receiver performance
Solution Approach 1:
The patent merges the impedance matching function with the LNA amplification function by integrating the active negative feedback structure directly into the LNA circuit. This consolidation eliminates the need for separate pi networks or two-stage LC matching circuits, reducing peripheral devices while maintaining wide bandwidth coverage. The integrated design also minimizes noise by reducing the number of discrete components and interconnections.
4Adaptability or versatility
If matching in a wide frequency band is implemented, then more frequency bands are covered, but blocking signal and useful signal cannot be well separated, increasing baseband circuit pressure
Solution Approach 1:
The active negative feedback structure provides frequency-selective impedance matching by adjusting the feedback network parameters to optimize matching for the desired frequency band while presenting high impedance to blocking signals. This local quality adjustment at different frequency points enables the circuit to selectively receive useful signals while rejecting blocking signals, even when operating across wide bandwidths.
Data Source
AI summary
The present disclosure provides a receiving circuit for adaptive impedance matching and an operating method thereof. The receiving circuit includes: a first amplification module configured to amplify an input signal input from an input end of the first amplification module to generate a first amplified signal; a frequency mixing module, an input end of which is connected to an output end of the first amplification module, and configured to down-convert the first amplified signal to generate a down-converted signal; and a second amplification module, an input end of which is connected to an output end of the frequency mixing module, and configured to amplify the down-converted signal to generate an output signal, wherein the first amplification module includes an active negative feedback structure for providing adaptive impedance matching in a first bandwidth range.