Dual-Path Input Circuit for Noise-Tolerant Level Shifting
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Solution Overview
Problem
Existing input circuits that convert high potential signals to low potential signals face challenges in setting an appropriate target inversion potential, leading to potential noise-induced logic inversions, and often require high withstanding voltage transistors, which increase manufacturing costs.
Innovation Solution
The input circuit employs a first and second path control circuit, along with a PMOS and NMOS transistor configuration, to control electrical connections based on input signal potentials, allowing for an appropriate target inversion potential and using low withstanding voltage transistors, thereby preventing unexpected logic inversions and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high withstanding voltage transistors are used in the input circuit, then the circuit can handle high potential signals, but the manufacturing cost increases
Solution Approach 1:
The patent divides the transistor circuit into two separate paths: a first path for normal signal processing using low withstanding voltage transistors, and a second path for handling high potential signals using high withstanding voltage transistors. This segmentation allows each path to use transistors with appropriate voltage ratings, reducing the need for expensive high-voltage transistors throughout the entire circuit.
Solution Approach 2:
The patent introduces a potential conversion circuit as an intermediary between the high potential input terminal and the low potential internal circuitry. This converter mediates the voltage level transition, allowing low withstanding voltage transistors to be used in the main signal path while still handling high potential inputs through the conversion process.
2Ease of operation
If the target inversion potential is set too low, then the circuit is more sensitive to input changes, but noise can cause unexpected logic inversions
Solution Approach 1:
The patent implements dynamic path selection based on the input signal potential level. The first path control circuit activates the first path when the input potential exceeds a first threshold, while the second path control circuit activates the second path when the input potential exceeds a second (higher) threshold. This dynamic switching optimizes both sensitivity and noise tolerance depending on the input conditions.
Solution Approach 2:
The patent changes the operational parameters of different transistor paths based on the input signal characteristics. By switching between paths with different threshold characteristics, the circuit adapts its inversion potential behavior to match the input signal conditions, achieving both high sensitivity for valid signals and high noise tolerance for invalid signals.
Data Source
AI summary
An input circuit includes an inverter, a first path control circuit and a second path control circuit. An input of the inverter is connected with a first node. A target inversion potential is higher than an inversion potential of the inverter. The first path control circuit electrically connects an input terminal and the first node when the input potential is higher than the target inversion potential, and blocks off an electrical connection between the input terminal and the first node when the input potential is lower than the target inversion potential. The second path control circuit electrically connects a ground terminal and the first node when the input potential is lower than a second inversion potential which is lower than the target inversion potential and blocks off the electrical connection between the ground terminal and the first node when the input potential is higher than the second inversion potential.