Rotating Harmonic Rejection Mixer for Device Mismatch Control
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Solution Overview
Problem
Conventional harmonic rejection mixers face challenges in effectively rejecting harmonic frequencies introduced by non-sinusoidal local oscillator signals due to device mismatches and phase deviations, leading to power consumption and area inefficiencies, with realistic harmonic rejection performance limited to around 30-40 dB at high frequencies.
Innovation Solution
A rotating harmonic rejection mixer design that cyclically rotates the mixed signal through multiple gain stages, using a master clock signal and weighted gain stages to combine outputs, reducing harmonic rejection issues while minimizing power and area consumption by shifting device matching problems to lower frequency passive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If very large device sizes are used in conventional harmonic rejection mixers, then device matching is improved and random mismatches are reduced, but power consumption and area increase significantly
Solution Approach 1:
The patent changes the operating parameters by using a rotating switch that cycles through different mixer stages, allowing the system to achieve improved device matching through temporal averaging rather than requiring all devices to be perfectly matched simultaneously. This parameter change enables harmonic rejection of 40-60 dB without requiring very large device sizes, thus reducing power consumption while maintaining manufacturing precision.
2Manufacturing precision
If very large device sizes are used in conventional harmonic rejection mixers, then device matching is improved and random mismatches are reduced, but area increases significantly
Solution Approach 1:
The patent employs parameter changes by implementing a rotating switch mechanism that cycles through multiple mixer stages, achieving improved device matching through time-averaged performance rather than requiring all devices to be perfectly matched at once. This approach reduces the required circuit area while maintaining manufacturing precision, as the system achieves harmonic rejection of 40-60 dB without needing very large device sizes.
3Manufacturing precision
If additional well-matched components are used to achieve 180 degree phase opposition, then LO signal phase accuracy is improved, but power consumption increases
Solution Approach 1:
The patent segments the LO signal path by distributing the signal to multiple mixer stages through a rotating switch, rather than requiring a single perfectly phase-matched path. This segmentation allows the system to achieve phase accuracy through the averaging effect of cycling through multiple stages, reducing the need for additional well-matched components and thereby reducing power consumption while maintaining manufacturing precision.
4Object-affected harmful factors
If conventional harmonic rejection mixer designs are used, then harmonic rejection of 30-40 dB is achieved, but stricter tolerances are required for other components in the receiver
Solution Approach 1:
The patent achieves superior harmonic rejection of 40-60 dB through parameter changes in the mixing process, specifically by using a rotating switch to cycle through multiple mixer stages with different LO phase relationships. This approach improves the harmonic rejection performance without imposing stricter tolerances on other receiver components, as the improvement comes from the dynamic switching mechanism rather than from tighter component specifications.
Data Source
AI summary
In one embodiment, the present invention includes a method for receiving a radio frequency (RF) signal and mixing the RF signal with a master clock to obtain a mixed signal, cyclically rotating the mixed signal to each of N gain stages for at least one cycle of the master clock, and summing the outputs of the N gain stages to provide an output signal.