Ring Oscillator Temperature Sensing Under Supply Noise
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Solution Overview
Problem
Ring oscillators used for temperature detection in electronic systems are affected by noise in the supply voltage, leading to inaccurate frequency readings that do not reflect the operating temperature, as noise variations mask temperature-induced frequency changes.
Innovation Solution
A temperature identification system incorporating a ring oscillator circuit and a frequency divider circuit, where the ring oscillator generates a signal that is divided by a divider value to reduce noise impact, with the temperature measurement module determining the operating temperature based on the divided signal, and optionally using a regulator to generate a regulated voltage with reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ring oscillator is used for temperature detection, then temperature information can be obtained through frequency measurement, but noise on the supply voltage line causes frequency variations that mask the temperature-induced frequency changes, reducing measurement accuracy
Solution Approach 1:
A frequency divider circuit is introduced as an intermediary between the ring oscillator and the temperature measurement module. This divider circuit divides the ring oscillator frequency by a predetermined value (e.g., 256) before it reaches the temperature measurement module, effectively filtering out high-frequency noise while preserving the temperature-dependent frequency variations. The division operation averages out random noise components, allowing accurate temperature detection even in noisy environments.
2Measurement precision
If the supply voltage line has large noise amplitude, then frequency variations due to noise mask the frequency variations due to temperature changes, but adding noise filtering components increases device complexity
Solution Approach 1:
The frequency divider circuit serves as a simple yet effective intermediary that reduces noise impact without requiring complex filtering components. By using a digital division operation instead of analog filtering, the solution maintains low circuit complexity while achieving noise rejection. The divider circuit can be implemented with simple digital logic, avoiding the need for additional capacitors, inductors, or active filtering stages.
Solution Approach 2:
The solution replaces potential analog noise filtering mechanisms (mechanical/electrical filtering components) with a digital frequency division approach. Instead of using complex analog circuits to filter noise, the patent uses a digital divider that naturally attenuates high-frequency noise through the division operation, substituting a simple digital process for what would otherwise require complex analog filtering hardware.
Data Source
AI summary
A temperature identification system may include temperature sensing circuitry and a temperature measurement module. The temperature sensing circuitry may include a ring oscillator that generates a ring oscillator output signal having a frequency that varies depending on an operating temperature on the ring oscillator. A frequency divider circuit may divide the frequency of the ring oscillator output signal such that two or more cycles of a noise component of supply voltage are averaged, which may reduce the impact that the noise has on the frequency of the ring oscillator output signal. In some embodiments, a regulator may supply a regulated voltage to the ring oscillator. The regulator may reduce the impact of the noise for low frequency components of the noise, while the frequency divider may reduce the impact for high frequency of the noise.