SAR-type ADC를 적용하여 빠른 Settling time을 갖는 2-step Buck converter

국문 초록 (Abstract)

Mobile application에 적용되는 2-step Buck converter를 소개한다. Successive Approximation Resistor (SAR)-type Analog to Digital Converter (ADC)를 사용하여 빠른 settling time을 갖는 2-step Buck converter를 소개한다. 이 구조는 Digital Pulse Width Modulator (DPWM)가 가질 수 있는 pulse의 width를 한정시켜줌으로써 settling time을 줄일 수 있다. Conventional Buck converter에 비해 rising time이 46.7%, falling time이 82.9% 빨라졌다. Test 결과 rising time이 24ms, falling time이 6ms으로 측정되었다. 이때의 current 변화는 8mA에서 140mA이고, 1.95kHz의 switching frequency를 가지며 off-chip inductor와 capacitor는 각각 22uH와 470uF이다. 본 2-step Buck converter는 0.18um CMOS 공정으로 설계되었다.

다국어 초록 (Multilingual Abstract)

This paper introduces the 2-step Buck converter using Successive Approximation Resistor (SAR)-type Analog to Digital Converter (ADC) for fast settling time in mobile applications. The 2-step Buck converter reduces settling time by restricting a segmented range of pulse width. Rising time and falling tipme are improved by 46.7% and 82.9% faster than conventional Buck converter respectively. Measured rising time and falling time of are 24ms and 6ms respectively when current changes from 8mA to 140mA at 1.95kHz switching frequency with the off-chip inductor of 22uH and the capacitor of 470uF. The 2-step Buck converter is fabricated in a 0.18um CMOS process.

목차 (Table of Contents)

• 제 1장 서론 1
• 제 2장 A 2-step Buck converter for fast settling time in mobile applications 7
• 2.1 Conventional Buck converter 8
• 2.1.1 Comparator 9
• 2.1.2 Ramp signal generator 11
• 2.1.3 Up-Down counter 12
• 2.1.4 Dead-time controller 15
• 2.1.5 DPWM generator of conventional Buck converter 16
• 2.2 A 2-step Buck converter 18
• 2.2.1 SAR-type ADC 19
• 2.2.2 Reset signal generator 20
• 2.2.3 DPWM generator of 2-step Buck converter 21
• 제 3장 Simulated result and measured result 23
• 3.1 Simulated results 23
• 3.2 Measured results 24
• 3.3 Top cell layout 26
• 3.4 Die photo 27
• 제 4장 결론 28
• 참고문헌 29
• 국문초록 32
• ABSTRACT 33