Temperature Sensor Using Digital CDS for Linear Voltage
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Solution Overview
Problem
Conventional temperature sensors generate non-linear voltage signals due to intrinsic nonlinear characteristics of transistors, making accurate temperature detection challenging.
Innovation Solution
A temperature sensor design that includes a band gap reference circuit to generate reference voltages, a voltage generation unit to produce proportional first and second voltages, and a digital CDS circuit to generate a digital signal by performing correlated double sampling on these voltages, effectively canceling out transistor nonlinearities and providing a linearly proportional digital signal for accurate temperature determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensors use transistor-based voltage generation, then device complexity is reduced, but measurement precision deteriorates due to nonlinear voltage signals
Solution Approach 1:
The voltage generation function is divided into multiple independent voltage generation units, each producing a specific voltage component. This segmentation allows the system to generate multiple voltages with different temperature coefficients independently, which are then combined to achieve linear temperature dependence while maintaining relatively simple individual circuit structures
Solution Approach 2:
The patent changes the temperature coefficient parameters of different voltage generation units to achieve linear temperature dependence. By selecting units with different temperature coefficients (positive and negative) and combining them in specific ratios, the overall system achieves linear voltage-temperature relationship, improving measurement precision without requiring complex compensation circuits
2Reliability
If temperature compensation is performed using semiconductor element characteristics, then temperature detection capability is improved, but reliability deteriorates due to temperature-dependent signal variations
Solution Approach 1:
The patent uses voltage generation units with opposite temperature coefficients to counterbalance each other's temperature-dependent variations. One unit provides positive temperature coefficient while another provides negative temperature coefficient, and their combination cancels out nonlinear temperature effects, achieving temperature-stable signals while maintaining temperature detection capability through the band gap reference circuit
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 accurate temperature detection by generating digital signals that are linearly proportional to temperature, improving the precision and reliability of temperature measurement across varying conditions.
Implementation Method 1
a band gap reference (BGR) circuit configured to generate a reference voltage proportional to a temperature
Implementation Method 2
a digital CDS circuit configured to generate a digital signal corresponding to the temperature by performing a digital correlated double sampling (CDS) operation on the first voltage and the second voltage
Data Source
AI summary
A temperature sensor includes a band gap reference (BGR) circuit, a voltage generation unit and a digital CDS circuit. The band gap reference (BGR) circuit generates a reference voltage proportional to a temperature. The voltage generation unit generates a first voltage and a second voltage based on the reference voltage, where the first voltage and the second voltage are proportional to the temperature. The digital CDS circuit generates a digital signal corresponding to the temperature by performing a digital correlated double sampling (CDS) operation on the first voltage and the second voltage. The temperature sensor is able to detect a temperature accurately.