Low-Voltage Digital Temperature Sensor Using MOS Varactor Ring Oscillators
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Solution Overview
Problem
Existing temperature sensors in processors and DRAMs face challenges such as high power consumption, large size, and vulnerability to voltage fluctuations, making them unsuitable for integration in modern computing systems.
Innovation Solution
A low-power-consumption low-voltage digital temperature sensor is designed using a first and second ring oscillator, integrators, a D trigger, and a linear optimization module, which utilizes the voltage characteristic of a MOS varactor to reduce voltage fluctuation sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal diffusivity-based sensors are used, then measurement precision and area are improved, but power consumption increases
Solution Approach 1:
The patent replaces the thermal diffusivity-based physical measurement system with a digital signal processing system. Instead of measuring temperature through thermal diffusion properties, the system uses ring oscillators to generate digital signals whose frequency ratios encode temperature information, substituting mechanical/physical measurement with electronic signal processing to achieve lower power consumption while maintaining accuracy
Solution Approach 2:
The patent changes the operating parameters by using dynamic frequency scaling and voltage scaling. The ring oscillators operate at frequencies that are scaled according to temperature conditions, and the system uses variable clocking mechanisms to adjust the measurement rate, thereby optimizing the balance between measurement precision and power consumption dynamically
2Use of energy by moving object
If DTMOST-based sensors are used, then power consumption and operating voltage are improved, but area increases
Solution Approach 1:
The patent segments the temperature sensing function into multiple independent ring oscillators with different temperature sensitivities. Each ring oscillator is a simple delay-element loop that can be implemented with minimal area, and their combined frequency ratio provides the temperature measurement, achieving low power consumption without requiring large area
Solution Approach 2:
The patent makes the ring oscillators serve multiple functions: they generate clock signals for the integrators, provide temperature-dependent frequency ratios for measurement, and their combined output enables both temperature sensing and digital output generation. This multi-functionality reduces the overall area required compared to dedicated separate circuits
3Area of stationary object
If logic supply voltage is used, then area is reduced, but reliability deteriorates due to noise and voltage variations
Solution Approach 1:
The patent implements feedback mechanisms where the output of the ring oscillators is fed back through integrators that accumulate phase information. The integrators continuously adjust their output based on the frequency differences between the two ring oscillators, creating a feedback loop that compensates for voltage variations and maintains stable temperature measurement despite supply voltage fluctuations
Solution Approach 2:
The patent introduces integrators as intermediary circuits between the ring oscillators and the final output. These integrators act as mediators that convert the frequency ratio information into stable digital outputs, filtering out the noise and voltage variations that would directly affect the measurement reliability
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 sensor achieves low power consumption, small size, high digitalization, and self-referencing capabilities, making it suitable for integration in processors and DRAMs while being immune to voltage fluctuations.
Implementation Method 1
the first ring oscillator additionally adopts the MOS varactor as a load capacitor, the voltage fluctuation sensitivity is reduced by utilizing the voltage characteristic of the varactor
Data Source
AI summary
A low-power-consumption low-voltage digital temperature sensor, which acquires temperature information by means of the frequency ratio of a first oscillation signal outputted by a first annular oscillator to a second oscillation signal outputted by a second annular oscillator. The first annular oscillator additionally uses an MOS varactor as a load capacitor, and uses the voltage characteristics of the MOS varactor to lower the power supply voltage fluctuation sensitivity, which is suitable for a low-power-consumption low-voltage environment; meanwhile, the sensor has the advantages of a small size, high digitization, self referencing and the like.