Low Leakage IO Circuit With Dynamic Switch Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronic devices face power leakage issues due to impedance paths in IO circuits that continue to draw power even when the chip is powered off, failing to meet strict leakage standards like those in HDMI specifications.
Innovation Solution
An IO circuit with a built-in control mechanism and switch circuit that disconnects the impedance path from the power supply when the chip is powered off, using PMOS and NMOS transistors to manage voltage differences and prevent leakage, allowing the pull-up resistor to function only during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pull-up resistor is provided in the IO circuit to maintain signal levels and match impedance, then signal exchange functionality is improved, but power leakage increases when the chip is powered off
Solution Approach 1:
The patent applies the dynamics principle by making the impedance path dynamically controllable through a switch circuit. The switch circuit changes its state based on the power supply status: it connects the pull-up resistor to the power supply during normal operation to maintain signal levels, and disconnects it when the power supply is off to prevent power leakage. This dynamic switching resolves the contradiction between maintaining reliable signal exchange and reducing power leakage.
2Stability of the object's composition
If the impedance path remains connected during power off to maintain signal levels, then signal integrity is improved, but leakage current increases violating HDMI specifications
Solution Approach 1:
The patent uses a switch circuit as an intermediary element between the power supply and the impedance path. This switch circuit acts as a mediator that controls the connection state based on power supply status. When the power supply is off, the switch circuit disconnects the impedance path, preventing leakage current while allowing the impedance path to be reconnected when power is restored, thus maintaining signal integrity without violating leakage current specifications.
3Loss of energy
If external transistors and additional power supplies are used to control the impedance path, then power leakage control is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies the self-service principle by designing a control circuit that automatically detects the power supply status and controls the switch circuit accordingly. The control circuit monitors the power supply voltage and autonomously determines when to connect or disconnect the impedance path, eliminating the need for external transistors and additional power supplies. This self-service mechanism achieves effective power leakage control while minimizing device complexity and manufacturing cost.
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
This solution effectively reduces power leakage by disconnecting the impedance path when the chip is powered down, meeting low-leakage standards without requiring external transistors or additional power supplies, thus reducing design and manufacturing costs and complexity.
Implementation Method 1
According to a relationship between voltages of the power supply and the pad (i.e., whether the power supply supplies power normally), the switch circuit selectively closes between the first and second nodes to control whether the impedance path conducts the power supply to the pad
Implementation Method 2
For example, the threshold voltage is an absolute value of a threshold voltage of the transistor. To further prevent other possible leakage paths, a bulk of the PMOS transistor is kept floating
Data Source
AI summary
A low-leakage IO circuit is provided. The IO circuit includes an impedance path between a pad and a power supply. The impedance path bypasses a signal path of the pad and includes a switch circuit. According to a relationship between voltages of the power supply and the pad of the IO circuit, the switch circuit selectively conducts the impedance path. When the power supply provides power normally, the switch circuit conducts the impedance path to provide a pull-up resistor between the pad and the power supply. When the power supply provides no power and its voltage is lower than a voltage of the pad, the switch circuit disconnects the conducting path to effectively reduce power leakage.