ADC Switching Circuit for Low-Leakage Sensor Measurement Modes
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Solution Overview
Problem
Existing analog/digital conversion circuits in measuring transducers face challenges in efficiently converting analog signals to digital values, particularly due to high leakage currents and limited flexibility in measurement modes, which affect the accuracy and versatility of sensor signal processing.
Innovation Solution
A circuit design that includes multiple switching devices and current source/sink circuits, allowing for six distinct measurement modes by selectively connecting these components to minimize leakage current and enhance measurement flexibility, utilizing a control circuit to switch between modes and a processor to map digital values to measured values using nonlinear measurement functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional switching devices are used in the circuit, then the circuit structure is simple, but high leakage currents occur which reduce measurement accuracy
Solution Approach 1:
The switching function is divided into multiple parallel switching devices (first switching device, second switching device, third switching device) that can be independently controlled. Each switching device handles specific connection tasks, allowing the circuit to achieve low leakage current by selectively activating only the necessary switching path while keeping others in high-impedance state.
Solution Approach 2:
Different switching devices are assigned different leakage current characteristics to specific circuit regions. The first switching device connects the current source to the first input, the second switching device connects the current sink to the second input, and the third switching device handles reference potential connections. Each device is optimized for its specific local function, minimizing overall leakage.
2Adaptability or versatility
If a fixed circuit configuration is used, then the circuit design is simple, but the measurement mode flexibility is limited
Solution Approach 1:
The circuit employs dynamic reconfiguration capability through multiple switching devices that can change connection topologies in real-time. The control unit dynamically switches between different measurement modes (e.g., connecting current source to different inputs, changing reference potential connections) based on the specific measurement requirements, enabling the circuit to adapt to various sensor types and measurement scenarios.
Solution Approach 2:
The circuit design incorporates multiple switching devices and current sources that enable a single circuit to perform multiple measurement functions. The same basic circuit structure can measure different physical quantities, support different sensor configurations, and operate in various measurement modes by simply reconfiguring the switching states, achieving universal applicability.
3Adaptability or versatility
If multiple switching devices and current sources are used, then measurement mode flexibility is enhanced, but the leakage current increases
Solution Approach 1:
The harmful leakage current paths are extracted and isolated by using multiple switching devices in parallel. When one switching device is activated for a specific measurement mode, the other switching devices are switched to high-impedance state, effectively removing their leakage paths from the active circuit. This extraction of unnecessary leakage paths minimizes total leakage current despite having multiple switching devices available.
Data Source
AI summary
A circuit for analog-digital conversion, which includes a first connection and a second connection and a third connection and a fourth connection for connecting a sensor, an analog-digital converter (ADC), whose first input is connected to the first connection and whose second input is connected to the second connection, a first current source circuit for outputting a first output current, a first switching device for the switchable connection of the first current source circuit to the first connection or to the third connection, a current source/sink circuit for outputting a second output current, a second switching device for the switchable connection of the current source/sink circuit to a reference potential or to the second connection, and a third switching device for the switchable connection of the reference potential to the second connection or to the fourth connection.