Rotating Harmonic Rejection Mixer With Cyclic Gain-Stage Switching
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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 performance degradation and increased power consumption.
Innovation Solution
A rotating harmonic rejection mixer design that cyclically rotates the mixed signal across multiple gain stages, using a master clock signal to improve matching and reduce harmonic rejection, while minimizing power and area consumption by employing smaller device sizes and better-matched passive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple mixers are used in conventional harmonic rejection mixers, then harmonic rejection capability is improved, but device area and power consumption increase
Solution Approach 1:
The patent divides the mixing function across multiple mixer stages (first mixer stage, second mixer stage, third mixer stage) that process the signal sequentially. Each stage contributes to harmonic rejection while sharing the processing load, allowing effective harmonic suppression without requiring all mixers to operate at full power simultaneously.
Solution Approach 2:
The patent employs periodic switching of the mixed signal between different gain stages using a rotating switch. The signal is rotated to different stages in a cyclic manner (first stage during first time period, second stage during second time period, third stage during third time period), enabling harmonic rejection through time-division multiplexing rather than requiring all stages to operate continuously.
2Object-affected harmful factors
If multiple mixers are used in conventional harmonic rejection mixers, then harmonic rejection capability is improved, but power consumption increases
Solution Approach 1:
The rotating switch periodically connects the mixed signal to different gain stages at different time periods. During each time period, only the active gain stage consumes significant power while others remain inactive or in low-power state. This time-division approach achieves harmonic rejection through multiple stages without requiring all stages to consume full power simultaneously.
Solution Approach 2:
The patent dynamically switches the signal path between different gain stages using a rotating switch controlled by phase-shifted clock signals. This dynamic switching allows the system to activate only the necessary mixer stages for current processing needs, reducing overall power consumption compared to having all stages continuously active.
3Manufacturing precision
If device sizes are increased to reduce random mismatches, then matching precision is improved, but device area and power consumption increase
Solution Approach 1:
The patent segments the mixing function across multiple separate mixer stages rather than using a single large mixer. Each individual mixer stage can use smaller, more easily matched devices while collectively achieving the required performance through their combined operation and periodic switching between stages.
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 solution achieves improved harmonic rejection with reduced power and area consumption, enabling dynamic control of harmonic rejection based on incoming signal frequency and preventing flicker noise, thus enhancing the performance of receivers like television and radio systems.
Implementation Method 1
the mixer typically multiplies the incoming wireless signal with a local oscillator signal to produce a signal that has spectral energy that is distributed at sums and differences of the local oscillator and incoming signal's frequencies
Implementation Method 2
a rotating switch to cyclically switch the mixed signal to a plurality of gain stages
Implementation Method 3
each scaling factor that scales the incoming signal may be in accordance with a predetermined sinusoidal function
Implementation Method 4
the outputs of each mixer stage are summed to provide a downconverted (or upconverted) output
Data Source
AI summary
In one embodiment, the present invention includes a mixer circuit to receive and generate a mixed signal from a radio frequency (RF) signal and a master clock signal, a switch stage coupled to an output of the mixer circuit to rotatingly switch the mixed signal to multiple gain stages coupled to the switch stage, and a combiner to combine an output of the gain stages.