Multi-mode Ring Oscillator for Iterative Temperature and Voltage Sensing
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Solution Overview
Problem
Integrated circuits (ICs) face challenges in monitoring temperature and voltage variations, which can lead to performance issues and damage due to the lack of dedicated sensors in close proximity to all circuit regions, especially in programmable ICs where custom user circuits may not be near temperature sensors.
Innovation Solution
Implementing multi-mode ring oscillator circuits that oscillate with different voltage-temperature responses in three modes, allowing for iterative frequency measurements to estimate temperature and voltage accurately, even in programmable hardware resources, thereby enabling effective monitoring of temperature and voltage across ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated temperature sensors are placed in close proximity to all circuit regions, then temperature monitoring precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The ring oscillator serves multiple functions: it acts as both a clock generator for digital logic and a temperature sensor. By measuring the oscillation frequency, which varies with temperature, the same circuit element provides both operational and sensing functions, eliminating the need for separate dedicated temperature sensors in each circuit region.
Solution Approach 2:
The ring oscillator monitors its own operating conditions by measuring its oscillation frequency, which is inherently dependent on temperature and voltage. This self-monitoring capability allows the circuit to detect temperature and voltage variations without requiring external sensing infrastructure.
2Measurement precision
If iterative frequency measurements are performed in multiple modes, then temperature and voltage estimation accuracy is improved, but measurement time increases
Solution Approach 1:
A coarse temperature and voltage estimate is obtained first through initial frequency measurements, which then serves as input for subsequent iterative refinements. This preliminary estimation allows the system to start with a reasonable approximation and progressively improve accuracy rather than requiring all measurements to be taken from scratch.
Solution Approach 2:
The measurement process is divided into multiple modes or iterations, where each mode measures frequency under different operating conditions. By segmenting the measurement into coarse estimation followed by refined measurements, the system achieves high accuracy while managing measurement time through prioritized sequencing.
Data Source
AI summary
Methods and circuits are disclosed for measuring temperature and/or voltage using ring oscillators. In an example implementation, temperature and/or voltage are determined using an iterative measurements of a ring oscillator. The ring oscillator oscillates with a different voltage-temperature response in each of the first, second and third modes. In each iteration, a first set of indications of frequency are determined for a ring oscillator in a first mode, a second mode, and a third mode. A coarse temperature estimate and a coarse voltage estimate of the ring oscillator are determined based on the indications of frequency measured in a first iteration. A more accurate temperature estimate and a more accurate voltage estimate of the ring oscillator are determined as a function of a second set of indications of frequency measured in a second iteration, the coarse temperature estimate, and the coarse voltage estimate.