Analog Measurement Control Circuit With Optical Isolation and Gain Matching
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Solution Overview
Problem
Conventional logic testers with a single I/O port cannot meet the varied requirements of analog measurement modules, leading to noise coupling and unstable measurements due to mismatched specifications.
Innovation Solution
A controlling circuit comprising a shift register, a photo-coupler, and a general purpose amplifier is used to isolate noise and adjust signal gain, allowing for multiple analog measurement modules to be controlled with a single I/O port by transmitting bits through photo-transmission and activating relays with different voltage level differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single I/O port is used to control analog measurement modules, then device complexity is reduced, but noise coupling occurs and measurement stability deteriorates
Solution Approach 1:
A photo-coupler is introduced as an intermediary component between the logic tester's I/O port and the analog measurement module. The photo-coupler optically transmits control signals while providing galvanic isolation, thereby preventing noise coupling from the digital ground (DGND) to the analog ground (AGND) and ensuring measurement stability without requiring additional I/O ports.
2Device complexity
If control signals are directly transmitted to analog measurement modules, then device complexity is reduced, but noise coupling from digital to analog grounds occurs
Solution Approach 1:
The photo-coupler serves as an isolating intermediary that breaks the direct electrical connection between digital and analog grounds. Control signals are converted to optical signals for transmission and then back to electrical signals on the analog side, effectively blocking noise coupling while maintaining functional control.
Solution Approach 2:
The patent replaces direct electrical signal transmission with optical signal transmission through the photo-coupler. This substitution eliminates the galvanic connection that causes noise coupling, allowing control signals to be transmitted without carrying digital ground noise to the analog measurement module.
3Measurement precision
If amplifiers with different gains are selected to match audio signal magnitudes, then measurement precision is improved, but device complexity increases due to relay switching requirements
Solution Approach 1:
The patent implements dynamic gain selection by using the photo-coupler to transmit control signals that activate different amplifiers based on the magnitude of the audio signal being measured. The isolated control circuit can dynamically switch between amplifiers with different gains (e.g., 20dB, 40dB, 60dB) to match the required signal level, improving measurement precision without requiring complex relay switching circuits on the analog side.
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 solution effectively isolates noise and adjusts signal gain, enabling stable measurements across analog measurement modules with different specifications using a single I/O port from the logic tester, reducing errors and fabrication costs.
Implementation Method 1
The photo-coupler is coupled to the shift register, for transmitting the plurality of bits through photo-transmission
Data Source
AI summary
In a controlling circuit, a photo coupler is used for isolating noises, and a general purpose amplifier is used for adjusting a gain, so that a logic tester may test analog signals in cooperation with relays having different specifications and operating voltage level differences in an analog measurement module. A shift register of each controlling circuit of a controlling module also transmits a test data signal to a next stage controlling circuit, so that a logic tester may simultaneously output a plurality of bits to multiple controlling circuits and multiple analog measurement modules by using merely one I/O port.