Passive Mixer Receiver Using Phase Differencing for Odd-Harmonic Rejection
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Solution Overview
Problem
Current radio frequency (RF) receiver architectures for portable communication devices rely on SAW filters and LNAs, which increase complexity and power consumption, and fail to effectively reject odd harmonics of RF signals, leading to interference issues.
Innovation Solution
A low noise receiver architecture that eliminates SAW filters and LNAs by using a passive mixer with a switching configuration and differencing circuit to generate gain-added output phases, combined with a summation filter to reduce odd harmonics, thereby enhancing signal quality and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SAW filters and LNAs are used in the receiver architecture, then signal protection and amplification are improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and removes the SAW filter and LNA components from the traditional receiver architecture. By eliminating these separate components, the invention achieves signal protection and amplification through the passive mixer's inherent characteristics rather than through dedicated external components, thereby reducing device complexity while maintaining signal integrity
Solution Approach 2:
The patent merges the functions of signal filtering and amplification into the passive mixer itself. The passive mixer is designed to perform both the mixing function and the signal protection/amplification that were previously handled by separate SAW filters and LNAs, consolidating multiple functions into a single component to reduce overall system complexity
2Reliability
If SAW filters and LNAs are used in the receiver architecture, then signal protection and amplification are improved, but power consumption increases
Solution Approach 1:
The patent removes the power-consuming LNA component from the architecture. By extracting the amplification function from a dedicated active LNA component and implementing it through the passive mixer's inherent signal processing capabilities, the invention eliminates the continuous power consumption associated with active amplification while maintaining signal strength
Solution Approach 2:
The passive mixer performs signal protection and amplification through its own inherent characteristics without requiring external power supply for these specific functions. The mixer structure itself provides the signal enhancement and protection that would otherwise require powered components, making the system self-sufficient for these critical signal processing tasks
3Productivity
If traditional mixer architecture is used, then signal downconversion is achieved, but odd harmonics are not effectively rejected
Solution Approach 1:
The patent introduces asymmetry in the switching configuration by using different numbers of switches in different phases (e.g., 2 switches in one phase, 1 switch in another phase). This asymmetric arrangement creates destructive interference for odd harmonic frequencies while maintaining effective downconversion of the desired signal, thereby rejecting harmonics through the unequal switching paths
Solution Approach 2:
The patent employs periodic switching actions with specific duty cycles and timing relationships among the multiple switches. By coordinating the periodic switching of switches with different phases and durations, the system achieves frequency multiplication and harmonic rejection, where the periodic nature of the switching creates frequency-selective response that suppresses odd harmonics
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 proposed solution achieves significant cost and area savings by eliminating external SAW filters and LNAs, while effectively rejecting odd harmonics, thereby improving the receiver's noise performance and reducing power consumption.
Implementation Method 1
a mixer can be implemented using a series of switches that switch differential components of a quadrature signal according to a local oscillator (LO) signal. The frequency of the LO signal is chosen so that a radio frequency signal mixed with the LO signal is converted to a desired frequency.
Implementation Method 2
a differencing circuit configured to combine the plurality of output phases such that an nth output phase is differenced with an (n+K)th output phase, resulting in gain-added output phases
Implementation Method 3
a summation filter configured to receive the gain-added output phases and configured to combine the gain-added output phases such that a response of the receiver effectively reduces odd harmonics of the RF signal
Data Source
AI summary
A low noise receiver includes a downconverter configured to receive a radio frequency (RF) signal, the downconverter comprising a switching architecture configured to generate a plurality of output phases based on a respective plurality of local oscillator (LO) signals, a differencing circuit configured to combine the plurality of output phases such that an nth output phase is differenced with an (n+K)th output phase, resulting in gain-added output phases, and a summation filter configured to receive the gain-added output phases and configured to combine the gain-added output phases such that a response of the receiver effectively reduces odd harmonics of the RF signal.