Substrate-Biased Delay Circuit for PVT-Stable Timing
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Solution Overview
Problem
Existing delay circuits in semiconductor elements, such as DRAM, face challenges in maintaining precise delay control due to significant variations in delay caused by changes in supply voltage, operating temperature, and manufacturing processes.
Innovation Solution
A voltage generating circuit comprising two transistors, where the voltage of the substrate of each transistor varies with parameters like supply voltage, operating temperature, or manufacturing process, is used to adjust the current through the transistors in the delay unit, thereby compensating for changes and maintaining precise delay control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional delay circuit is used in DRAM, then the delay can be controlled, but the delay varies significantly with changes in supply voltage, operating temperature, and manufacturing process
Solution Approach 1:
The patent changes the electrical parameters (substrate voltage) of the transistors in the delay circuit based on detected variations in supply voltage, temperature, or process characteristics. By dynamically adjusting these parameters, the circuit compensates for environmental and manufacturing variations, maintaining stable delay performance across different operating conditions
Solution Approach 2:
The patent implements a feedback mechanism where the actual delay or operating conditions are monitored, and the substrate voltage of the transistors is adjusted accordingly. This closed-loop control ensures that delay variations caused by external factors are compensated in real-time, improving both reliability and stability
2Measurement precision
If the delay circuit is made more complex to compensate for parameter variations, then delay precision can be maintained, but the circuit complexity increases
Solution Approach 1:
Instead of adding complex compensation circuits, the patent achieves delay precision by dynamically adjusting the substrate voltage parameter of existing transistors. This approach maintains delay precision through parameter optimization rather than structural complexity
Solution Approach 2:
The delay circuit performs self-compensation by using its own output or a portion of it to control the substrate voltage adjustment. This self-regulating mechanism maintains precision without requiring external complex control systems
Data Source
AI summary
A voltage generating circuit includes a first transistor and a second transistor. Voltage of a substrate of the first transistor varies with a first parameter. The first parameter is any one of a supply voltage, an operating temperature, as well as a manufacturing process of the voltage generating circuit. A gate of the first transistor is connected to a drain of the first transistor. The substrate of the first transistor serves as an output of the voltage generating circuit. A gate of the second transistor is connected to a drain of the second transistor.