Optical Encoder Interpolation Circuit With Four-Comparator Routing
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Solution Overview
Problem
Conventional optical encoders face challenges in achieving high positioning accuracy while maintaining low power consumption and silicon area usage, especially when requiring high interpolation factors, as they necessitate increased numbers of comparators, leading to higher power consumption and reduced detection accuracy.
Innovation Solution
The optical encoder employs a phase shifter circuit, multiplexers, and a limited number of comparators (only four) to generate and process phase-shifted signals, utilizing multiplexers and digital circuits to selectively route signals to comparators, thereby maintaining low power consumption and silicon area usage even at high interpolation factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of comparators is increased to achieve higher positioning accuracy, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent divides the signal processing into multiple stages: a phase shifter circuit generates multiple phase-shifted signals, multiplexers selectively route these signals, and only four comparators are needed to process the segmented signal paths. This segmentation allows high interpolation factors without proportionally increasing the number of comparators.
Solution Approach 2:
The patent employs dynamic signal routing through multiplexers that selectively connect different phase-shifted signals to the comparators based on the interpolation factor. This dynamic configuration allows the same four comparators to handle various interpolation factors (e.g., 16x, 32x, 50x) without requiring a fixed increase in comparator数量.
2Measurement precision
If the number of comparators is increased to achieve higher positioning accuracy, then measurement precision is improved, but power consumption increases
Solution Approach 1:
By segmenting the signal processing function across a phase shifter circuit, multiplexers, and a minimal set of four comparators, the patent achieves high interpolation factors without the exponential increase in power consumption that would result from using many comparators in parallel.
Solution Approach 2:
The four comparators serve multiple functions by processing different phase-shifted signals routed through the multiplexers. This multi-functionality allows the same comparators to achieve various interpolation factors (16x, 32x, 50x) without requiring additional comparator circuits for each function.
3Measurement precision
If the number of comparators is increased to achieve higher positioning accuracy, then measurement precision is improved, but silicon area increases
Solution Approach 1:
The patent segments the interpolation function across a phase shifter circuit that generates multiple phase-shifted signals, multiplexers that route these signals, and only four comparators. This segmentation achieves high interpolation factors (e.g., 50x) without requiring a large array of comparators, thus reducing silicon area.
Solution Approach 2:
The multiplexers act as intermediaries between the phase shifter circuit and the comparators, selectively routing the appropriate phase-shifted signals to the four comparators. This intermediary function enables high interpolation factors without directly increasing the comparator count, thereby reducing silicon area consumption.
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
This configuration allows for high positioning accuracy with reduced power consumption and silicon area usage, achieving significant savings in both metrics compared to conventional designs, with the 50-times interpolation circuit example demonstrating 70% silicon area savings and 1/16th the current consumption.
Implementation Method 1
The phase shifter circuit is configured to receive a first signal, a second signal, a third signal and a fourth signal from an amplifier, and output 4N phase shifted signals
Implementation Method 2
The first multiplexer is configured to receive 2N phase shifted signals among the 4N phase shifted signals from the phase shifter circuit
Implementation Method 3
The first comparator is configured to receive a first pair of phase shifted signals via a plurality of first switches of the first multiplexer and generate a first comparison signal
Data Source
AI summary
There is provided an optical encoder including a phase shifter circuit, two multiplexers, two digital circuits and four comparators. The phase shifter circuit receives signals from an amplifier and outputs multiple phase shifted signals. Each of the two multiplexers receives a half of the multiple phase shifted signals and outputs two pairs of phase shifted signals, each pair having 180 degrees phase difference, respectively to two comparators connected thereto. Each of the two digital circuits controls the corresponding multiplexer to select the two pairs of phase shifted signals from the half of the multiple phase shifted signals.