ADC Dithering with Shift Signals for Higher Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing analog-to-digital (AD) converters with low resolution face challenges in achieving effective oversampling due to difficulties in generating stable white noise with appropriate bandwidth, and the Σ-Δ type sampling requires complex digital processing and expensive semiconductor products.
Innovation Solution
An AD conversion apparatus and method that generates n shift signals with different amplitudes, compounds these signals with the input analog signal to improve resolution, and processes the resulting signals to produce output digital signals with enhanced precision, allowing for improved resolution without the need for high-cost noise generation or complex digital processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If white noise is generated using a negative feedback circuit with an operational amplifier for noise amplification, then the noise bandwidth can be increased, but the cost and complexity of the device increases significantly
Solution Approach 1:
The patent replaces expensive operational amplifiers with inexpensive resistors that generate thermal noise. The resistor is a simple, cheap component that naturally produces white noise without requiring complex active circuits. This resolves the contradiction by achieving the desired noise bandwidth using a low-cost, simple passive component instead of an expensive operational amplifier.
Solution Approach 2:
The patent substitutes an active electronic system (operational amplifier circuit) with a passive physical phenomenon (thermal noise of resistor). Instead of using an active circuit to generate and amplify noise, the invention exploits the natural thermal agitation of electrons in a resistor, which inherently produces white noise across a broad bandwidth without requiring complex circuitry.
2Measurement precision
If a Zener diode is used to generate white noise, then noise can be obtained, but current consumption increases and temperature stability deteriorates
Solution Approach 1:
The patent replaces the Zener diode with a simple resistor, which is a more reliable and temperature-stable component. Resistors have predictable thermal noise characteristics that are less sensitive to temperature variations compared to Zener diodes, thereby improving reliability while maintaining noise generation capability.
3Measurement precision
If the number of sampling operations is increased to improve resolution, then measurement precision improves, but measurement time increases
Solution Approach 1:
The patent uses periodic dithering signals (square wave, triangular wave, or sawtooth wave) added to the input signal before AD conversion. These periodic signals cause the analog signal to oscillate around its true value, enabling the low-resolution AD converter to effectively capture higher resolution information through dithering. This allows resolution improvement without requiring excessive sampling operations, thus reducing measurement time.
Solution Approach 2:
The patent changes the parameters of the input signal by adding dithering signals with different waveforms and amplitudes. By modulating the signal with these periodic dithering waves, the effective resolution of the AD converter is enhanced. This parameter modification enables high-resolution measurement with fewer samples, resolving the time-precision trade-off.
4Productivity
If Σ-Δ type sampling is used to reduce measurement time, then sampling speed improves, but digital processing complexity and hardware cost increase
Solution Approach 1:
The patent replaces complex digital processing (Σ-Δ modulation and decimation) with simple analog dithering techniques. By adding periodic dithering signals in the analog domain before the AD converter, the system achieves high-resolution conversion using a simple parallel-sampling architecture. This eliminates the need for complex digital filters and processors required by Σ-Δ type sampling, thereby reducing hardware cost and complexity while maintaining fast sampling speed.
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 approach simplifies AD conversion while improving resolution, reducing the need for costly noise amplification and complex digital processing, enabling more precise AD conversion with a simplified composition.
Implementation Method 1
Thermal noise of a resistance is widely understood as an example of white noise. The noise voltage v n is represented as v n = (4kTRΔf) 1/2
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An AD conversion apparatus includes a shift signal generating portion configured to generate n shift signals (n is a natural number greater than one) of which amplitudes are different from each other; a shift signal controlling portion configured to control the shift signal generating portion; a compounding portion configured to compound input analog signal and the n shift signals sequentially into n first signals; an AD converting portion configured to execute AD conversion to convert the n first signals into n second signals; and a signal processing portion configured to calculate an average of the n second signals to generate output digital signal.