Multi-Stage Sample and Hold Circuit Leakage Reduction
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Solution Overview
Problem
Conventional sample and hold circuits face challenges in minimizing current leakage, leading to reduced hold time and increased power consumption, especially when sampling and holding voltages for extended periods.
Innovation Solution
A multi-stage sample and hold circuit design featuring a first sample node for low precision and a second sample node for high precision, with switch circuits that include transistors with bulk material contact areas to reduce leakage, and a switching mechanism that isolates nodes during the hold phase to limit current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional sample and hold circuits are used to sample and hold voltages for extended periods, then the hold function is achieved, but current leakage increases leading to reduced hold time and increased power consumption
Solution Approach 1:
The circuit is divided into multiple stages with separate sample nodes (first sample node for low precision, second sample node for high precision) and distinct switch circuits for each stage. This segmentation allows each stage to be optimized independently, with the bulk switch circuit specifically designed to minimize leakage for extended hold periods while other stages handle sampling functions.
Solution Approach 2:
A bulk switch circuit with bulk material contact area is introduced as an intermediary component between the sample nodes and the held voltage. This bulk switch circuit acts as a mediator that provides a controlled path for charge storage while minimizing leakage current through its bulk material contact, thereby extending hold time without proportionally increasing power consumption.
2Use of energy by stationary object
If the hold phase is extended to allow longer periods between voltage refresh operations, then power consumption is reduced, but current leakage through the switching circuit increases
Solution Approach 1:
The bulk switch circuit's bulk material contact is configured to receive a voltage signal that automatically reduces current leakage between the bulk material and the sample nodes during the hold phase. This self-adjusting mechanism allows the circuit to maintain low leakage currents over extended periods without requiring external intervention or increasing power consumption.
Solution Approach 2:
The circuit changes the electrical parameters of the bulk switch by applying a specific voltage signal to the bulk material contact. This parameter change modifies the leakage characteristics of the bulk material, reducing current leakage during the hold phase and enabling extended hold times with lower average current consumption.
3Measurement precision
If multiple sample nodes are used to provide different precision levels, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The sampling circuit is segmented into distinct stages with separate sample nodes - a first sample node for low precision sampling and a second sample node for high precision sampling. Each stage has its own switch circuit, allowing independent optimization and simplifying the design of each segment while achieving overall high precision through the combination of stages.
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
The solution effectively reduces current leakage and extends hold time, allowing for lower average current consumption and longer periods between voltage refresh operations, while maintaining high precision and accuracy.
Implementation Method 1
The bulk material contact area may be configured to receive a voltage signal configured to reduce current leakage between the bulk material and at least one of the first node and the second node during a hold phase
Data Source
AI summary
A circuit may include a first sample node configured to provide a low precision sample of an input signal, a second sample node configured to store a high precision sample of an input signal, and a first switch circuit coupled between an input and the first sample node. The circuit may further include a second switch circuit coupled between the first sample node and the second sample node and configured to limit leakage current that could discharge the second sample node.