PMOS Switch Circuit Gate Control for Leakage Blocking
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Solution Overview
Problem
PMOS transistors in switch circuits experience parasitic leakage current when the power source is turned off, as they cannot be completely turned off due to their characteristics, leading to unwanted signal leakage.
Innovation Solution
Incorporating a P-type control transistor coupled between the input and control ends of the PMOS transistor switch, which receives a second input signal to turn on and prevent the leakage current from reaching the output, ensuring the PMOS transistor is fully turned off when the power source is off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PMOS transistor is used as a switch in the circuit, then the switch can be controlled by logic levels, but the PMOS cannot be completely turned off when power is off, causing parasitic leakage current
Solution Approach 1:
A control transistor is introduced as an intermediary component between the input signal source and the PMOS transistor gate. This control transistor acts as a mediator that prevents the input signal from directly reaching the PMOS gate when the control signal is active, thereby eliminating the parasitic leakage path while maintaining normal switch operation when needed
2Device complexity
If the PMOS transistor is left in its natural state without additional control components, then the circuit structure remains simple, but leakage current occurs from source to base or drain when power is off
Solution Approach 1:
The control transistor serves as an intermediary element that blocks the leakage current path without significantly complicating the overall circuit architecture. By placing this single control component in series with the gate control path, the solution adds minimal complexity while effectively eliminating the harmful leakage effect
Data Source
AI summary
A switch circuit is provided. The switch circuit includes a P-type transistor switch and a first P-type control transistor. The P-type transistor switch includes a first control end, a first output end, and a first input end. The first input end receives a first input signal whose logic level is one. The first P-type control transistor is coupled to the first input end and the first control end. The first P-type control transistor includes a second control end. The second control end receives a second input signal whose logic level is zero to turn on the first P-type control transistor. When the first P-type control transistor is turned on, the first input signal is transmitted to the first control end of the P-type transistor switch to turn off the P-type transistor switch.