Temperature-Dependent Timer Circuit for Low-Power Refresh Control
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Solution Overview
Problem
Semiconductor chip power management systems face challenges in reducing power consumption during standby and sleep modes due to inefficient refresh rate mechanisms, which are often set for worst-case conditions like high temperatures, leading to increased power usage and space overhead.
Innovation Solution
A temperature-dependent timer circuit with an exponential refresh mechanism that minimizes power consumption by adjusting the refresh period based on leakage current, using a comparator and band gap circuitry to generate reference voltages, allowing for reduced refresh cycles at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refresh rate is set for worst case conditions (high temperatures), then the system maintains accuracy across all temperatures, but power consumption increases and space overhead increases
Solution Approach 1:
The refresh rate is made dynamic by using a temperature-dependent timer that automatically adjusts the refresh period based on the current temperature. At lower temperatures where leakage current is reduced, the refresh period is extended, reducing the frequency of refresh operations and thereby lowering power consumption while still maintaining reference accuracy when needed.
Solution Approach 2:
The system changes the refresh period parameter based on temperature conditions. Instead of using a fixed refresh rate designed for worst-case high temperature scenarios, the refresh period is variable and adapts to actual operating conditions, allowing longer periods at lower temperatures to reduce power consumption.
2Reliability
If a constant low power clock runs to set the refresh rate, then the refresh mechanism is reliable, but power consumption increases and substrate area increases
Solution Approach 1:
The constant low power clock that was previously required to maintain reliable refresh timing has been removed from the system. The temperature-dependent timer circuit generates its own timing signals without requiring a continuously running clock, thereby eliminating the associated substrate area and power consumption while maintaining refresh reliability through temperature-adaptive timing.
3Use of energy by moving object
If the refresh period is extended at lower temperatures, then power consumption is reduced, but reference accuracy may deteriorate
Solution Approach 1:
The temperature-dependent timer uses temperature sensing feedback to dynamically adjust the refresh period. The circuit monitors temperature conditions and automatically modifies the refresh timing accordingly, ensuring that references are refreshed at appropriate intervals to maintain accuracy while maximizing power savings during extended hold phases between refreshes.
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 significantly reduces power consumption in semiconductor devices by optimizing the refresh period according to temperature variations, thereby conserving power and minimizing space overhead in low-power modes.
Implementation Method 1
The third node is biased to place the transistor in a subthreshold region of operation to change a voltage of the second node at a rate exponentially dependent upon temperature
Implementation Method 2
The output of the comparator changes state when the voltage of the second node crosses a voltage of the first node
Data Source
AI summary
A timer to provide pulses at a comparator output wherein a frequency of the pulses is dependent on temperature, wherein providing each pulse includes biasing a first input of the comparator at a voltage and operating a transistor in a subthreshold region of operation to change the voltage of the first input of a comparator at a rate dependent upon temperature. The output of the comparator changes state when the voltage of the first input crosses a voltage of a second input of the comparator.