CTAT Bias Ring Oscillator Temperature Sensing
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Solution Overview
Problem
Conventional temperature sensing systems in system-on-chip (SOC) designs are costly and power-intensive, requiring diodes, bandgap reference voltage circuits, and analog-to-digital converters, which complicate implementation and increase area and power consumption, while CMOS ring oscillators are sensitive to power supply variations and have limited temperature sensitivity.
Innovation Solution
A temperature sensing apparatus utilizing a CMOS ring oscillator with a complementary-to-absolute-temperature (CTAT) bias generator and regulator to generate a regulated bias voltage, allowing the ring oscillator to produce an oscillation signal that is insensitive to power supply variations, thereby enhancing temperature sensitivity and reducing the need for complex reference circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensing systems use diodes, bandgap reference voltage circuits, and analog-to-digital converters, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and eliminates complex reference circuits (bandgap reference voltage circuits, analog-to-digital converters) from the temperature sensing system, retaining only the essential CMOS ring oscillator and bias generator components. This extraction maintains temperature measurement functionality while dramatically reducing circuit complexity and power consumption.
Solution Approach 2:
The patent replaces expensive, complex reference circuits with simpler, more economical CMOS ring oscillators and bias generators. The simplified circuit architecture uses readily available standard CMOS components rather than specialized expensive reference circuitry, reducing both cost and complexity.
2Device complexity
If CMOS ring oscillators are used for temperature sensing, then device complexity is reduced, but sensitivity to power supply variations increases
Solution Approach 1:
The patent introduces a CTAT bias generator as an intermediary component between the power supply and the CMOS ring oscillator. This bias generator produces a complementary-to-absolute-temperature bias voltage that actively compensates for power supply variations, allowing the ring oscillator to maintain stable frequency-temperature characteristics even when power supply voltage fluctuates.
Solution Approach 2:
The patent changes the biasing parameter of the CMOS ring oscillator from a fixed voltage to a CTAT (complementary-to-absolute-temperature) bias voltage. This parameter change enables the oscillator to compensate for power supply variations automatically, as the CTAT bias voltage varies with temperature in a manner that counteracts the effects of power supply fluctuations on oscillation frequency.
3Device complexity
If CMOS ring oscillators are used for temperature sensing, then device complexity is reduced, but temperature sensitivity is limited
Solution Approach 1:
The patent changes the biasing parameter from fixed voltage to CTAT bias voltage, which enhances the temperature sensitivity of the ring oscillator. The CTAT bias voltage creates a stronger temperature-dependent frequency response, improving the oscillator's ability to detect temperature changes while maintaining simple circuit architecture.
Solution Approach 2:
The patent makes the bias voltage dynamic and temperature-dependent through the CTAT bias generator, rather than using a static fixed voltage. This dynamic biasing approach allows the ring oscillator to adapt its operating characteristics to temperature changes, enhancing temperature sensitivity while keeping the circuit simple.
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
This approach provides a cost-effective and power-efficient temperature sensing solution with improved sensitivity and linearity, suitable for modern SOC designs, particularly as semiconductor processes advance and power supply voltages decrease.
Implementation Method 1
a bias generator suitable for generating a complementary-to-absolute-temperature (CTAT) bias voltage
Implementation Method 2
a ring oscillator suitable for receiving the regulated bias voltage and generating an oscillation signal based on the regulated bias voltage
Data Source
AI summary
An apparatus for temperature sensing may include: a bias generator suitable for generating a complementary-to-absolute-temperature (CTAT) bias voltage; a regulator suitable for regulating a bias voltage by using CTAT bias voltage and outputting a regulated bias voltage; and a ring oscillator suitable for receiving the regulated bias voltage and generating an oscillation signal based on the regulated bias voltage.