Multi-Phase Mixing Circuit for Higher Harmonic Suppression
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Solution Overview
Problem
Existing mixers in wireless communication technology face challenges in suppressing higher order intermodulation interferences, which deteriorate signal quality and affect the performance of transceivers, especially at lower intermediate frequencies.
Innovation Solution
A mixing circuit with a multi-phase generation module, a quadrature phase generation module, a harmonic suppression module, and a Gilbert mixing module, which generates and filters square wave signals to suppress higher order harmonic components, improving the harmonic suppression ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mixers are used to down-convert signals, then the mixing function is achieved, but higher order intermodulation interferences are generated that deteriorate signal quality
Solution Approach 1:
The mixing function is divided into multiple parallel mixing paths with different phase shifts (0°, 45°, 90°, 135°). Each path processes the signal independently and then they are combined. This segmentation allows the harmful higher order intermodulation products to be distributed and suppressed across different paths, while the desired signal components constructively interfere to improve signal quality.
Solution Approach 2:
The patent uses asymmetric phase shifting in the multi-phase mixing paths rather than symmetric phase relationships. By introducing specific phase differences (45° increments) and combining the outputs with appropriate weighting, the circuit creates asymmetric interference patterns that suppress harmful harmonics while preserving the desired signal.
2Measurement precision
If image suppression techniques are implemented, then image frequency rejection is improved, but higher order harmonic suppression is not adequately addressed
Solution Approach 1:
The patent extends the traditional two-dimensional mixing approach (in-phase and quadrature) to a four-dimensional multi-phase mixing system with 0°, 45°, 90°, and 135° phase shifts. This additional dimensional complexity provides extra degrees of freedom to suppress not only image frequencies but also higher order harmonics simultaneously, addressing both suppression requirements.
3Volume of moving object
If lower intermediate frequency is used, then device portability is improved, but higher order intermodulation interferences move closer to the spectral line
Solution Approach 1:
The multi-phase mixing operation is performed preliminarily on the RF signal before down-conversion to the intermediate frequency. By applying the phase-diverse mixing at the higher RF stage, the harmful intermodulation products are suppressed before they can fold into the intermediate frequency band, preventing them from appearing close to the desired spectral line even when using lower IF frequencies.
Data Source
AI summary
The present disclosure provides a mixing circuit with high harmonic suppression ratio, including: a multi-phase generation module, which receives a first input signal and generates eight first square wave signals with a phase difference of 45°; a quadrature phase generation module, which receives a second input signal and generates four second square wave signals with a phase difference of 90°; a harmonic suppression module, connected with an output end of the quadrature phase generation module to filter out higher order harmonic components in the second square wave signals; and a mixing module, connected with output ends of the multi-phase generation module and the harmonic suppression module to mix output signals of the multi-phase generation module and the harmonic suppression module. The mixing circuit with high harmonic suppression ratio adds a harmonic suppression module on the basis of multi-phase mixing, thereby improving the harmonic suppression ratio of the output signal.