High-Resolution Encoder Interpolation Circuit for Accurate Gain Control
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Solution Overview
Problem
Existing interpolation methods for high-resolution encoders require complex circuits for automatic gain control of sinusoidal signals, which are difficult to implement due to linearity issues with multipliers and adders, and struggle to determine peak amplitudes accurately from a single measured voltage.
Innovation Solution
The improved interpolation method generates intermediate digital signals by comparing the potential of an input analogue signal with its inverse at shifted argument values, allowing for automatic gain control using the voltage of the upper waveform envelope of reference potentials, eliminating the need for complex multiplying or adding circuits and enabling peak amplitude determination with high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex multiplying or adding circuits are used for automatic gain control, then peak amplitude determination can be achieved, but device complexity increases and linearity issues arise
Solution Approach 1:
The patent extracts the essential function of peak amplitude detection by removing complex multiplying and adding circuits. Instead, it uses a simplified circuit that compares the first input analogue signal with the inverted third input analogue signal through resistor chains, achieving peak amplitude determination without the complexity of traditional methods.
Solution Approach 2:
The patent replaces the mechanical/electronic complex circuit system (multipliers and adders) with an electrical field-based comparison system using resistor chains and comparators. This substitution maintains measurement functionality while dramatically reducing circuit complexity and improving linearity.
2Manufacturing precision
If analogue reference signals are used in the conversion process, then interpolation can be performed, but differential nonlinearity increases at higher frequencies
Solution Approach 1:
The patent removes analogue reference signals from the conversion process entirely. Instead of using external reference signals that cause frequency-dependent nonlinearity, the system generates all necessary reference potentials internally through resistor chains, eliminating the source of differential nonlinearity while maintaining interpolation accuracy.
Solution Approach 2:
The patent introduces resistor chains as intermediary elements that generate reference potentials without requiring external analogue reference signals. These resistor chains act as mediators between the input signals and comparators, providing stable, frequency-independent reference levels that ensure monotonic conversion.
3Speed
If the separation time between output signal slopes is reduced to a few nanoseconds, then high slope resolution is achieved, but measurement precision requirements increase
Solution Approach 1:
The patent performs preliminary amplitude normalization by comparing signals through resistor chains before the final conversion stage. This preliminary action ensures that even with rapid slope transitions, the amplitude information is preserved and normalized, allowing high-speed operation without sacrificing measurement precision.
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 approach simplifies automatic gain control and accurately determines peak amplitudes with a relative accuracy of ±0.029, independent of signal frequency and without requiring analogue reference signals, ensuring monotonous and steady conversion with reduced differential nonlinearity.
Implementation Method 1
each intermediate digital signal results from a comparison of the potential of the first input analogue signal at a shifted value of its observed argument and with the amplitude reduced according to the resistance ratio, to the potential, which is inverse to said potential, of the third input analogue signal
Data Source
AI summary
Intermediate digital signals Fi(α), Gi(α), i=1, . . . I, are generated, which result from a comparison of reference potentials of the first input analogue signal at a shifted value of its observed argument and with a suitably reduced amplitude to the potential, which is inverse to said potential, of the third input analogue signal at the same shifted value of the observed argument and with the amplitude reduced in said way, the shifted argument values being uniformly distributed within the first half-period. A value U of the voltage is measured at any value of the observed argument as at that time the highest one of the voltages at terminals with said reference potentials. An actual peak amplitude A of the input analogue signals is determined as A=kI,mU where the factor kI,m is a quotient of the peak amplitude of said input analogue signals and of the mean value of the voltage waveform envelope of the reference potentials pertaining to said peak amplitude.When the proposed method is used to automatically control the gain, said voltage U is conducted directly to the input of an automatic gain control circuit, whereat the input voltage of this circuit is set to the mean value of the voltage waveform envelope of the reference potentials.