Tracking Passgate Circuit for Low-Leakage Signal Sensing
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Solution Overview
Problem
Existing passgate switch circuits in semiconductor circuits suffer from significant current leakage, especially when the voltage difference between input and output is large, leading to inaccuracies in signal sensing and calibration processes, particularly in high-speed applications.
Innovation Solution
Implementing a tracking switch circuit with multiple, series-coupled passgate switches and tracking circuits that minimize the voltage difference across the switch when it is turned off, reducing current leakage by activating tracking circuits that track input/output states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional passgate switch circuits are used, then the circuit structure is simple, but current leakage is significant especially when voltage difference between input and output is large
Solution Approach 1:
The patent divides a single passgate switch into multiple series-coupled passgate switches (first, second, and third passgate switches). This segmentation allows intermediate junction nodes to be created, which can then be tracked by tracking circuits to minimize voltage differences across each individual switch, thereby reducing overall current leakage while maintaining reasonable structural complexity
Solution Approach 2:
The patent introduces tracking circuits as intermediary elements that monitor and minimize voltage differences at intermediate junction nodes between series-coupled passgate switches. These tracking circuits act as mediators that actively reduce the voltage stress across each switch, thereby reducing current leakage without requiring a complete redesign of the basic passgate structure
2Measurement precision
If multiple passgate switches are coupled in parallel to increase capacity, then signal sensing accuracy improves, but current leakage increases
Solution Approach 1:
By segmenting each parallel passgate switch into multiple series-coupled switches with tracking circuits, the patent enables accurate signal sensing through parallel configuration while simultaneously reducing current leakage through the tracking mechanism. Each parallel path independently implements the segmentation strategy, allowing the system to benefit from both increased capacity and reduced leakage
3Loss of energy
If tracking circuits are added to reduce current leakage, then energy loss decreases, but device complexity increases
Solution Approach 1:
The tracking circuits are introduced as intermediary elements that provide a targeted solution to the current leakage problem. Rather than redesigning the entire passgate structure, the tracking circuits act as auxiliary mediators that specifically address voltage difference minimization at critical junction nodes, achieving leakage reduction with controlled increases in complexity
Solution Approach 2:
The tracking circuits are applied locally at specific intermediate junction nodes where voltage differences most significantly impact current leakage. This localized application of tracking functionality allows the system to reduce overall leakage without requiring tracking circuits throughout the entire circuit, thereby managing the trade-off between energy loss and device complexity
Data Source
AI summary
Some examples include tracking switches that may be used as passgates such as for sensing circuit multiplexers. The tracking switches include tracking circuits to provide off-state voltages at inner passgate junction nodes to reduce leakage current in the tracking switch when it is to be off.