Body-Biased Isolation Circuit for Leakage-Free Signal Switching
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Solution Overview
Problem
Conventional isolation circuits using P-type and N-type transistors fail to reliably couple or isolate circuits due to body effects, leading to signal truncation or leakage.
Innovation Solution
An isolation circuit design incorporating a first switch set, a second switch set, and a body bias voltage generator that automatically couples or isolates circuits based on voltage levels, ensuring proper operation by managing body bias voltages for P-type and N-type transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional P-type and N-type transistors are used for isolation, then the circuit can selectively couple or isolate circuits, but signal truncation occurs due to body effect and signal leakage paths are formed
Solution Approach 1:
The patent introduces a body bias voltage generator as an intermediary component that provides controlled body bias voltages to the transistors. This mediator component adjusts the body effect dynamically, enabling the isolation circuit to prevent signal leakage and truncation while maintaining reliable coupling or isolation functionality.
Solution Approach 2:
The patent changes the body bias voltage parameter dynamically based on the operational state. By adjusting the body bias voltage to be higher than the source/drain voltage when isolation is needed, and appropriate when coupling is needed, the circuit eliminates signal leakage paths and prevents signal truncation, thereby improving reliability without the harmful effects of conventional fixed-bias transistors.
2Reliability
If body bias voltage is adjusted to prevent signal leakage, then isolation reliability improves, but device complexity increases due to additional control circuits
Solution Approach 1:
The body bias voltage generator serves multiple functions: it provides body bias to prevent signal leakage, controls the coupling/isolation state, and adapts to different operational conditions. This multi-functional component achieves improved isolation reliability without requiring separate complex control circuits for each function, thereby limiting the increase in device complexity.
Data Source
AI summary
An isolation circuit is provided. The isolation circuit is coupled to an output and an input node and includes a first set, a second switch set, and a body bias voltage generator. The first switch set couples a switch control node to a second voltage when a first voltage is at a first voltage level, and couples the switch control node to the input node when the first voltage is at a second voltage level. The second switch set couples the output node to the input node when the first voltage is at the first voltage level, and isolates the output node from the input node when the first voltage is at the second voltage level. The body bias voltage generator selectively provides a higher one of the first voltage and a voltage on the input node to a body of the second switch set.