Pass Gate Off-Isolation via Over-Voltage Circuit Control
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Solution Overview
Problem
Off-state leakage in pass gates, such as switch and transistor pass gates, causes harmonic distortion of signals, particularly in electronic devices with shared connectors like USB connectors, leading to reduced performance and inability to receive or transmit certain signals due to unwanted current leakage when a pass gate is disabled.
Innovation Solution
A circuit configuration that includes a pass gate control circuit, over-voltage circuits, and a power supply select circuit to manage voltage levels and isolate nodes, ensuring minimal current leakage by comparing input voltages and selectively coupling the output to the supply rail, thereby maintaining isolation even when a pass gate is disabled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pass gate is disabled to isolate signal lines, then signal isolation is improved, but off-state leakage current causes harmonic distortion
Solution Approach 1:
An over-voltage circuit is introduced as an intermediary component between the pass gate control and the signal lines. This circuit monitors voltage levels and activates isolation mechanisms when over-voltage conditions are detected, thereby reducing off-state leakage current without compromising signal isolation performance
Solution Approach 2:
The invention changes the voltage parameter dynamically by using an over-voltage circuit to detect and respond to voltage levels. When over-voltage is detected, the circuit adjusts the isolation state of the pass gate, effectively controlling leakage current through parameter-based activation
2Adaptability or versatility
If multiple pass gates share a common connector, then device versatility is improved, but leakage from disabled pass gates causes signal distortion
Solution Approach 1:
The over-voltage circuit serves as a mediator that monitors the common connector and individual pass gate states. When it detects voltage indicative of disabled pass gates, it activates isolation to prevent leakage into shared signal lines, maintaining versatility while eliminating distortion
Solution Approach 2:
The invention implements a feedback mechanism where the over-voltage circuit continuously monitors voltage levels at the common connector and pass gate terminals. This feedback information is used to dynamically control the isolation state, preventing leakage from disabled pass gates in multi-pass gate configurations
Data Source
AI summary
This document discusses methods and apparatus for preventing or reducing sub-threshold pass gate leakage. In an example, an apparatus can include a pass gate configured to electrically couple a first node with a second node in a first state and to electrically isolate the first node from the second node in a second state, control logic configured to control the pass gate, wherein the control logic includes a supply rail, and an over-voltage circuit configured to compare voltages received at a plurality of input nodes and to couple an output to an input node a highest voltage. In an example, the output of over-voltage circuit can be selectively coupled to the supply rail.