Single-Capacitor Temperature Sensor Modulation for Accurate Duty Cycles
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Solution Overview
Problem
Conventional CMOS temperature sensors with bipolar transistors require complex designs and high accuracy Analog-to-Digital Converters, and duty-cycle-modulated temperature detection schemes using two capacitors increase chip area and compromise detection accuracy due to capacitance mismatch.
Innovation Solution
A modulation circuit with a comparator, charging capacitor, and switch modules that reuse a single charging capacitor by switching its voltage comparison phases, reducing chip area and improving accuracy through dynamic switch control and PTAT current sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two capacitors are used in the duty-cycle-modulated temperature detection scheme, then the temperature detection can be performed, but the chip area increases and detection accuracy is compromised due to capacitance mismatch
Solution Approach 1:
The patent merges the functions of two separate capacitors into a single capacitor by implementing a duty-cycle modulation circuit that alternates the capacitor's connection between two different voltage comparison paths. This single capacitor serves both comparison functions sequentially, eliminating the need for two separate capacitors and their associated matching issues, thereby reducing chip area while maintaining detection accuracy
Solution Approach 2:
The patent employs dynamic switching control to alternately connect the single capacitor to different voltage comparison paths during different time periods. The control module dynamically changes the capacitor's connection state based on the detection phase, enabling one capacitor to perform the functions that previously required two capacitors, thus reducing chip area without compromising measurement precision
2Measurement precision
If two capacitors are used in the duty-cycle-modulated temperature detection scheme, then the temperature detection can be performed, but the design complexity increases
Solution Approach 1:
The patent combines multiple circuit functions into a single integrated module. The single capacitor with dynamic switching control replaces the complex dual-capacitor configuration, reducing the number of components and interconnections. This merging approach simplifies the overall circuit design while maintaining the required temperature detection accuracy through duty-cycle modulation
Solution Approach 2:
The single capacitor in the patent serves multiple functions by being dynamically switched between different voltage comparison paths. This multi-functional design eliminates the need for separate dedicated capacitors for each comparison path, reducing both component count and design complexity while preserving the dual-voltage-comparison capability needed for accurate temperature detection
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 reduces chip area, saves cost, and enhances detection accuracy by eliminating capacitance mismatch issues and minimizing power consumption, while allowing for the use of capacitors with larger capacitance density.
Implementation Method 1
a charging module including a charging capacitor and a charging current source
Implementation Method 2
a comparison module including a comparator; a first input end of the comparator is connected with a first end of the first switch, a second end of the first switch is supplied with a first voltage. A second input end of the comparator is connected with a first end of the second switch, a second end of the second switch is supplied with a second voltage
Implementation Method 3
improving accuracy through dynamic switch control and PTAT current sources
Data Source
AI summary
A modulation circuit for voltage to duty-cycle conversion is provided. A first input end and a second input end of a comparator are supplied with a first voltage and a second voltage via a first switch and a second switch respectively. An output end of the comparator outputs a comparison result signal. A charging end of a charging capacitor is connected with a charging current source and a grounding reset module, and is connected with the first input end via a third switch, and is connected with the second input end via a fourth switch. When the comparison result signal flips over, a control module controls the grounding reset module to switch an on-off state of a first switch group including the first switch and the fourth switch and a second switch group including the second switch and the third switch.