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A Temperature – and Supply- Variation Robust 2nd-Order Sigma-Delta Modulation for Capacitive Sensing

Title
A Temperature – and Supply- Variation Robust 2nd-Order Sigma-Delta Modulation for Capacitive Sensing
Authors
Jaewoong Kim
DGIST Authors
Kim, Jaewoong; Je, Minkyu; Lee, Junghyup
Advisor(s)
이정협
Co-Advisor(s)
Minkyu Je
Issue Date
2020
Available Date
2020-06-23
Degree Date
2020-02
Type
Thesis
Description
Capacitance to digital converter, VCO quantizer, Sigma-Delta modulation, Supply variation, temperature variation
Abstract
In this paper, I proposed a temperature- and supply variation robust 2nd-order sigma-delta modulation circuit for capacitive sensing. Capacitive sensing by conventional circuits is basically supply sensitive. Capacitance is sensed by reading the charge that is equal to the difference between the capacitance value of the capacitor and the capacitor to be sensed. In this method, the amount of charge is dependent on the supply, so it is insensitive to supply variation. In this paper, the capacitance is read by using the time determined by the discharge characteristics when a capacitor called T0V meets the resistance component. The charge accumulated in the capacitor is certainly influenced by the supply value, but capacitive sensing is performed using the characteristic that the time taken to discharge the charge to zero is always constant. In the process, VCO (Voltage-Controlled-Oscillator) based ADC (Analog-to-Digital Converter) was used to increase the resolution by utilizing the noise shaping effect of sigma-delta ADC. In the process, the resistor is switched to a switched capacitor to obtain robust characteristics against temperature variations. Unlike resistance whose values change with temperature, capacitance are relatively robust to temperature effects. By using the characteristics, a circuit having robust characteristics in temperature variation as well as robust in supply variation.
Table Of Contents
Abstract i List of contents iii List of figures iv List of figures v Ⅰ. Introduction 1.1 Motivation and Objective 1 1.2 Theses outline 3 ⅠI. Supply- Variation Robust 2nd-Order Sigma-Delta Modulation 2.1 Supply Independent Technique 4 2.2 Injection Locking Current Controlled Oscillator 8 2.3 VCO Based ADC 13 2.4 Full Architecture 16 2.4.1 Control Block 19 2.4.2 Block Diagram 21 2.5 Schematic and Layout 23 III. Temperature- and Supply- Variation Robust 2nd-Order Sigma-Delta Modulation 3.1 Switched Capacitor DAC 31 3.2 Switched Capacitor Clock Generator 36 3.3 Control Block 38 3.4 Schematic 39 IV. Simulation and Measurement Result 4.1 Resistor DAC Circuit 42 4.1.1 Measurement Result 42 4.2 Switched Capacitor DAC Circuit 45 4.2.1 Simulation Result 45 V. Conclusion
URI
http://dgist.dcollection.net/common/orgView/200000287038
http://hdl.handle.net/20.500.11750/12013
DOI
10.22677/Theses.200000287038
Degree
Master
Department
Information and Communication Engineering
University
DGIST
Related Researcher
  • Author Lee, Junghyup Integrated Nano-Systems Laboratory
  • Research Interests Analog and Mixed Signal IC Design; Smart Sensor Systems; Bio-medical ICs and Body Channel Communication Systems
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Collection:
Department of Information and Communication EngineeringThesesMaster


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