Compensated Delay Circuit for Voltage and Temperature Stability
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Solution Overview
Problem
Conventional delay circuits in integrated circuits face challenges in maintaining a constant delay due to variations in supply voltage and temperature, which affects the synchronization of internal and external signals.
Innovation Solution
A temperature and voltage compensated delay circuit is designed using a constant current source with temperature-dependent and inverse temperature-dependent current generators, ensuring that the current provided to the delay stages is independent of temperature variations, and the delay is maintained constant by adjusting the relative weights of these currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional delay circuit is designed with simple delay stages, then the device complexity is reduced, but the delay precision varies with voltage and temperature changes
Solution Approach 1:
The patent changes the electrical parameters of the delay circuit by introducing voltage-dependent current mirrors and temperature-compensated current sources. These components dynamically adjust the current flowing through the delay stages based on supply voltage variations and temperature conditions, thereby maintaining constant delay precision without increasing the fundamental circuit topology complexity
Solution Approach 2:
The patent introduces intermediate compensation circuits including voltage-dependent current mirrors and temperature-compensated current sources that act as mediators between the power supply/temperature environment and the delay stages. These intermediary components isolate the delay stages from voltage and temperature variations, ensuring stable delay precision while keeping the overall structure manageable
2Reliability
If the delay circuit is made insensitive to voltage and temperature, then the reliability of signal synchronization is improved, but the device complexity increases due to additional compensation components
Solution Approach 1:
The patent employs parameter-changing components such as voltage-dependent current mirrors that automatically adjust their operating parameters (current) in response to supply voltage changes. Temperature-compensated current sources similarly adjust parameters based on temperature. These dynamic parameter adjustments ensure reliable signal synchronization while using standard integrated circuit building blocks rather than complex external components
Solution Approach 2:
The patent implements feedback mechanisms where the voltage-dependent current mirrors sense the supply voltage and adjust the current flowing through the delay stages accordingly. Temperature-compensated current sources use feedback from temperature sensing to maintain constant current. This automatic feedback control ensures reliable synchronization without requiring complex external control systems
3Manufacturing precision
If delay stages use long channel length transistors for high resistance, then the delay precision is improved, but the area of the circuit increases
Solution Approach 1:
Instead of relying solely on long channel length transistors to achieve high resistance, the patent changes the approach by using voltage-dependent current mirrors and temperature-compensated current sources that provide stable high resistance through active control. This allows the use of shorter channel length transistors, reducing the circuit area while maintaining delay precision through dynamic parameter adjustment rather than static geometric dimensions
Data Source
AI summary
A delay circuit provides a voltage and temperature compensated delayed output signal. The delay circuit includes a first delay stage that receives an input signal, and generates a delayed output signal from the input signal. The delay circuit also includes a second delay stage that receives the delayed output signal of the first delay stage, and generates a delayed output signal from the output of the first delay stage. The first delay stage and the second delay stage are coupled a voltage supply. The magnitude of the delay of the second delayed signal is inversely proportional to the magnitude of the supply voltage to substantially the same degree that the delayed output signal of the first delay stage is proportional to the magnitude of the supply voltage.