Zero-IF Receiver Feedback Circuit for Quadrature Imbalance
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Solution Overview
Problem
Zero-IF receivers experience significant performance degradation due to gain imbalance between positive and negative frequency offsets in wide signal bandwidths, necessitating conventional circuit optimizations that increase power consumption and cost.
Innovation Solution
A receiver and zero-IF transceiver design incorporating two parallel mixers and weighted feedback circuits with complex impedance-based feedback to compensate for asymmetric frequency responses, utilizing trans-impedance amplifiers and weighted feedback resistors to adjust signal phases and amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If zero-IF architecture is used, then circuit structure is simplified and cost is reduced, but gain imbalance between positive and negative frequency offsets causes performance degradation
Solution Approach 1:
The patent implements a feedback mechanism where the output of each mixer is fed back to the input of the other mixer through feedback circuits. This feedback loop enables automatic compensation for gain imbalance between positive and negative frequency offsets, resolving the performance degradation issue while maintaining the simplified zero-IF architecture
Solution Approach 2:
The patent introduces asymmetric feedback circuit configurations to compensate for the asymmetric gain imbalance inherent in zero-IF receivers. By using different feedback paths and components for positive and negative frequency offsets, the system achieves balance compensation without requiring complex symmetric compensation devices
2Reliability
If complex compensation devices are added to reduce frequency offset fluctuation, then performance is improved, but power consumption and cost increase
Solution Approach 1:
The patent enables the receiver system to self-compensate for frequency response imbalance through the feedback mechanism. The system uses its own output signals to automatically adjust and compensate for gain imbalance, eliminating the need for external complex compensation devices and reducing power consumption
Solution Approach 2:
The feedback circuits serve as intermediary elements that mediate between the mixers to achieve balance compensation. These intermediate feedback paths enable automatic adjustment without requiring complex external compensation devices, thus reducing both power consumption and cost
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
The design effectively alleviates quadrature imbalance, reducing power consumption and costs by avoiding the need for complex compensation devices while improving performance in wideband zero-IF receivers.
Implementation Method 1
each mixer is configured to receive a baseband signal, perform frequency mixing on the baseband signal
Implementation Method 2
each weighted feedback circuit is configured to receive the mixed signal output by a corresponding mixer, and perform adjustment on the received mixed signal using a complex impedance-based feedback
Implementation Method 3
each weighted feedback circuit includes a trans-impedance amplifier
Data Source
AI summary
Disclosed are a receiver and a zero-IF transceiver. The receiver includes a frequency mixer circuit including two mixers in parallel and weighted feedback circuits respectively corresponding to the mixers, each mixer having an output end connected to an input end of the corresponding weighted feedback circuit, and each weighted feedback circuit having an output end connected to an input end of the other weighted feedback circuit. Each mixer is configured to receive a baseband signal, mix the baseband signal, and input the resulting mixed signal to the corresponding weighted feedback circuit; and each weighted feedback circuit is configured to receive the mixed signal from the corresponding mixer, and adjust the received mixed signal using complex impedance-based feedback to compensate for an asymmetric frequency response in a wideband zero-IF receiver. Weighted feedback circuits are utilized for adjustments using complex impedance-based feedbacks, thereby alleviating quadrature imbalance and reducing power consumption and cost.