PMOS Voltage Selection Circuit for Non-Floating High-Voltage Output
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Solution Overview
Problem
Conventional selection circuits in electronic devices require additional control signals to manage multiple supply voltages, leading to increased circuit complexity and performance degradation when voltages are close or equal, resulting in suboptimal high-voltage applications.
Innovation Solution
A selection circuit comprising a main and auxiliary selection circuit with transistors configured to select and stabilize output voltage based on the difference or equality of input voltages, using symmetrical transistor structures to maintain output voltage without floating, thus eliminating the need for additional control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional selection circuit is used to select between multiple supply voltages, then voltage selection function is achieved, but additional control signals are required increasing circuit complexity
Solution Approach 1:
The selection circuit automatically selects the highest voltage among multiple input voltages without requiring external control signals. The circuit uses the input voltages themselves to control the selection process through the transistor network, making it self-sufficient and eliminating the need for additional control signal lines.
Solution Approach 2:
The selection circuit can handle multiple supply voltages (e.g., 2.5V, 6V, and any other voltages between them) using the same circuit structure. The circuit universally outputs the highest voltage regardless of which combination of input voltages is applied, providing versatile voltage selection capability.
2Reliability
If a selection circuit outputs the highest voltage among multiple supply voltages, then high-voltage applications are supported, but when voltages are close or equal the circuit shuts off and outputs a voltage lower than all supply voltages
Solution Approach 1:
The circuit dynamically adjusts its behavior based on the relationship between input voltages. When voltages are significantly different, it operates in high-voltage output mode. When voltages are close or equal, it transitions to a stable voltage output mode that prevents the floating output problem, adapting its operation to the input conditions.
Solution Approach 2:
The auxiliary transistors act as intermediary elements that become active when the main selection transistors cannot properly select a voltage. These intermediary transistors provide a fallback conduction path that ensures the output voltage remains stable and close to the input voltages rather than floating, bridging the gap when primary selection fails.
3Measurement precision
If additional control signals are added to control voltage output, then voltage selection precision is improved, but circuit area increases
Solution Approach 1:
The circuit uses the input voltages themselves as control signals for the transistor gates, eliminating the need for external control signal lines. The voltage levels directly control which transistors conduct, providing precise voltage selection without requiring additional control signal routing that would consume circuit area.
Data Source
AI summary
A selection circuit includes a main selection circuit and an auxiliary selection circuit. When a first voltage and a second voltage are different, the main selection circuit selects a higher one of the first voltage and the second voltage as an output voltage. When the first voltage and the second voltage are equal, the auxiliary selection circuit generates the output voltage according to the first voltage and the second voltage.