PWM I/O Module Circuit for Compact Analog-Digital Output Control
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Solution Overview
Problem
Existing control systems for power plants and manufacturing processes face challenges in miniaturization due to increased cost and space requirements, as well as high power consumption and heat generation, primarily because of the complex circuit configurations needed for various signal modes and the necessity of separate components for analog and digital output modes.
Innovation Solution
The proposed I/O module uses a common controller connected via I/O modules with a PWM modulator and demodulator, a shared current source, and a multiplexer to enable efficient switching between digital and analog output modes, reducing the need for operational amplifiers and minimizing circuit size while maintaining precision through a simple circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate current sources and switching elements are provided for analog and digital output modes, then signal transmission precision is maintained, but device complexity and mount area increase
Solution Approach 1:
The patent applies universality by designing a single current source circuit that can operate in multiple modes (analog output and digital output) through PWM signal control. The same current source circuit replaces both the previously separate current source and switching element, allowing it to function as an analog current source when receiving analog control signals and as a digital switching element when receiving PWM signals. This multi-functional design reduces device complexity while maintaining signal transmission precision.
2Measurement precision
If separate current sources and switching elements are provided for analog and digital output modes, then signal transmission precision is maintained, but mount area increases
Solution Approach 1:
The patent applies merging by combining the previously separate current source circuit and switching element into a single integrated current source circuit. The switching element is merged into the current source structure, where the same transistor serves both as the current source for analog mode and as the switching element for digital mode. This consolidation significantly reduces the mount area while preserving the functional capabilities and precision of both modes.
3Measurement precision
If operational amplifiers are provided for each channel in current sources, then output precision of each channel is maintained, but cost and mount area increase
Solution Approach 1:
The patent applies universality by designing a single operational amplifier that serves multiple channels through time-division multiplexing. The operational amplifier is shared among multiple channels, with each channel being sequentially activated and controlled by the PWM signal. This allows one operational amplifier to maintain the output precision for multiple channels without requiring a separate operational amplifier for each channel, thereby reducing device complexity and cost.
4Reliability
If circuit configuration is provided for each channel, then channel independence is maintained, but cost and mount area increase proportionally with number of channels
Solution Approach 1:
The patent applies merging by combining multiple channel circuits into a single integrated circuit structure. Multiple channels share common components including the current source, operational amplifier, and control logic, with channel switching achieved through PWM signal timing. This unified design maintains channel independence through temporal separation while dramatically reducing the total quantity of circuit configurations compared to having separate circuits for each channel.
5Adaptability or versatility
If interface circuit size increases, then functionality is enhanced, but power consumption and heat generation increase
Solution Approach 1:
The patent applies universality by designing a compact interface circuit where a single current source circuit performs multiple functions (analog output, digital output, switching). This multi-functional design reduces the overall circuit size compared to having separate circuits for each function. The reduced circuit size directly lowers power consumption and heat generation while maintaining full functionality across all operating modes.
Data Source
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AI summary
An input/output (I/O) module is configured to connect a controller and a field device. The I/O module includes a PWM (pulse width modulation) demodulator configured to demodulate a PWM signal that is input from the controller, a current source configured to output a current based on an output signal of the PWM demodulator to the field device, a resistance connected in line with the current source, and a feedback circuit configured to feed back an output current of the current source to the PWM demodulator via the controller.