Ring Oscillator Temperature Sensor for Low-Area Digital Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing temperature sensors for on-chip heat management face challenges in meeting requirements for small area, strong anti-interference ability, low cost, and voltage sensitivity, particularly in advanced CMOS process nodes where complex chip designs lead to increased heating issues.
Innovation Solution
A temperature sensor circuit comprising a NAND gate and K delay units, where each delay unit consists of n stage inverters connected with PMOS and NMOS transistors, utilizing an exponential relationship between leakage current and temperature to provide digital output, allowing for flexible configuration and accurate temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional temperature sensors are used for on-chip heat management, then temperature measurement can be achieved, but the chip area occupied is large and voltage sensitivity is high
Solution Approach 1:
The patent replaces traditional analog temperature sensing mechanisms with a digital ring oscillator-based sensing system. The ring oscillator uses CMOS inverters and delay units to convert temperature changes into frequency changes, eliminating the need for large analog sensing circuits and reducing voltage sensitivity issues.
Solution Approach 2:
The patent changes the measurement parameter from voltage-based to frequency-based. By using the ring oscillator's output frequency as the measurement parameter, the system achieves better voltage insensitivity and smaller area occupancy while maintaining temperature measurement accuracy.
2Measurement precision
If more inverters are added to increase measurement accuracy, then temperature measurement accuracy improves, but measurement time increases
Solution Approach 1:
The patent introduces reconfigurable delay units with controllable inverter stages that can dynamically adjust the number of inversion stages based on measurement requirements. This allows the system to optimize between speed and accuracy by activating only the necessary number of delay units for each measurement cycle.
Solution Approach 2:
The patent implements a partial action approach where only K delay units (out of potentially more available units) are activated for each measurement. This selective activation allows the system to achieve sufficient measurement accuracy without the overhead of processing through all possible delay units, thereby reducing measurement time.
3Adaptability or versatility
If digital output is implemented for temperature monitoring, then integration with digital circuits is improved, but circuit complexity increases
Solution Approach 1:
The patent creates a universal ring oscillator circuit that serves multiple functions: temperature sensing, frequency generation, and digital output. The same CMOS inverters and delay units that provide the oscillating signal also directly interface with digital logic, eliminating the need for separate analog-to-digital conversion circuits and reducing overall system complexity.
4Area of stationary object
If ring oscillator structure is used for temperature sensing, then area occupancy is reduced, but voltage sensitivity remains an issue
Solution Approach 1:
The patent substitutes voltage-based measurement with frequency-based measurement. The ring oscillator's output frequency is measured digitally, and since frequency measurement is inherently more resistant to voltage variations than voltage measurement, the system achieves reduced voltage sensitivity while maintaining small area occupancy.
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 enables high-accuracy temperature measurement with digital output, reduced design complexity, low power consumption, and robustness against voltage fluctuations, suitable for a wide temperature range and low voltage operation, while minimizing area occupancy and self-heating.
Implementation Method 1
There can be an exponential relationship between leakage current (Ioff) of MOS transistor and temperature (T)
Data Source
AI summary
A temperature sensor includes a NAND gate and a plurality of delay units. The NAND gate includes a first and a second input terminals, and an output terminal. The first input terminal is configured to receive an external starting control signal. The plurality of delay units are connected in series. An input end of the first delay unit is connected to the output terminal of the NAND gate. An output end of the last delay unit is connected to the second input terminal of the NAND gate, thereby forming a ring oscillator structure. The temperature sensor can realize conversion of temperature-leakage-frequency based on the ring oscillator structure in a temperature range of −40˜125° C., thereby simplifying design complexity and achieves high accuracy.