Double-Integration A/D Converter Range Extension Beyond Reference Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing A/D converters with double integration type configurations face limitations in measuring input voltages exceeding the second reference voltage, leading to a restricted measurement range and decreased accuracy due to the lower limit value of the output voltage, which prevents accurate measurement beyond a certain input voltage threshold.
Innovation Solution
Incorporating a second comparator to compare the output voltage with a third reference voltage, allowing the logic circuit to control the switches and extend the measurement range by accurately counting charging and discharging periods, even when the input voltage exceeds the second reference voltage, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a double integration type A/D converter is used, then conversion functionality is provided, but the measurement range is restricted due to the lower limit value of the output voltage
Solution Approach 1:
The patent divides the measurement process into two distinct phases: an integration period where the input voltage is integrated, and a deintegration period where a reference voltage is applied to discharge the capacitor. This segmentation allows the converter to handle input voltages beyond the traditional limit by extending the measurement through phase separation.
Solution Approach 2:
The patent implements periodic switching between the integration phase and deintegration phase using control signals. By alternately applying the input voltage and reference voltage in periodic cycles, the system can measure voltages exceeding the conventional limit while maintaining accurate conversion through rhythmic charge-discharge operations.
2Measurement precision
If the input voltage exceeds the second reference voltage, then the measurement range should be extended, but the output voltage reaches a saturation point causing decreased accuracy
Solution Approach 1:
The patent uses comparator circuits to monitor the output voltage and generate control signals that regulate the switching between integration and deintegration phases. This feedback mechanism ensures that the capacitor voltage remains within valid measurement ranges, preventing saturation and maintaining measurement accuracy even when input voltages exceed traditional limits.
Solution Approach 2:
The patent performs preliminary integration of the input voltage during a controlled time period before switching to deintegration. By pre-charging the capacitor to a controlled level and then systematically discharging it with a known reference voltage, the system can accurately measure high input voltages without reaching saturation, as the measurement is completed before the saturation point is reached.
Data Source
AI summary
An A/D converter includes: an integrating circuit including: an amplifier including a first input end and a second input end connected to an application end of first reference voltage, a capacitor connecting the first input end and an output end of the amplifier, a first resistor connected between an application end of input voltage and the first input end, a first switch connected between the application end of the input voltage and the first input end, a second resistor connected between an application end of second reference voltage and the first input end, and a second switch connected between the application end of the second reference voltage and the first input end; a first comparator including a first input end connected to the output end and a second input end connected to the application end of the first reference voltage; and a switch controller controlling the first and second switches.