A 2.5 V 10b 120 MSample/s CMOS Pipelined ADC with High SFDR

높은 SFDR을 갖는 2.5 V 10b 120 MSample/s CMOS 파이프라인 A/D 변환기

  • Park, Jong-Bum (Dept. of Electronic Engineering, Sogang University) ;
  • Yoo, Sang-Min (Dept. of Electronic Engineering, Sogang University) ;
  • Yang, Hee-Suk (Dept. of Electronic Engineering, Sogang University) ;
  • Jee, Yong (Dept. of Electronic Engineering, Sogang University) ;
  • Lee, Seung-Hoon (Dept. of Electronic Engineering, Sogang University)
  • 박종범 (西江大學校 電子工學科) ;
  • 유상민 (西江大學校 電子工學科) ;
  • 양희석 (西江大學校 電子工學科) ;
  • 지용 (西江大學校 電子工學科) ;
  • 이승훈 (西江大學校 電子工學科)
  • Published : 2002.07.01

Abstract

This work describes a 10b 120 MSample/s CMOS pipelined A/D converter(ADC) based on a merged-capacitor switching(MCS) technique for high signal processing speed and high resolution. The proposed ADC adopts a typical multi-step pipelined architecture to optimize sampling rate, resolution, and chip area, and employs a MCS technique which improves sampling rate and resolution reducing the number of unit capacitor used in the multiplying digital-to-analog converter (MDAC). The proposed ADC is designed and implemented in a 0.25 um double-poly five-metal n-well CMOS technology. The measured differential and integral nonlinearities are within ${\pm}$0.40 LSB and ${\pm}$0.48 LSB, respectively. The prototype silicon exhibits the signal-to-noise-and-distortion ratio(SNDR) of 58 dB and 53 dB at 100 MSample/s and 120 MSample/s, respectively. The ADC maintains SNDR over 54 dB and the spurious-free dynamic range(SFDR) over 68 dB for input frequencies up to the Nyquist frequency at 100 MSample/s. The active chip area is 3.6 $mm^2$(= 1.8 mm ${\times}$ 2.0 mm) and the chip consumes 208 mW at 120 MSample/s.

본 논문에서는 높은 해상도와 고속 신호 샘플링을 위해 병합 캐패시터 스위칭(merged-capacitor switching:MCS) 기법을 적용한 10b 120 MSample/s CMOS 파이프라인 A/D 변환기(analog-to- digital converter:ADC) 회로를 제안한다. 제안하는 ADC의 전체 구조는 응용되는 시스템의 속도, 해상도 및 면적 등의 사양을 고려하여 다단 파이프라인 구조를 사용하였고, MDAC(multiplying digital-to- analog converter)의 캐패시터 수를 50 %로 줄임으로써 해상도와 동작 속도를 동시에 크게 향상시킬 수 있는 MCS 기법을 적용하였다. 제안하는 ADC는 0.25 um double-poly five-metal n-well CMOS 공정을 이용하여 설계 및 제작되었고, 시제품 ADC의 DNL(differential nonlinearity)과 INL(integral nonlinearity)은 각각 ${\pm}$0.40 LSB, ${\pm}$0.48 LSB 수준을 보여준다. 100 MHz와 120 MHz 샘플링 주파수에서 각각 58 dB와 53 dB의 SNDR(signal-to-noise-and-distortion ratio)을 얻을 수 있었고, 100 MHz 샘플링 주파수에서 입력 주파수가 나이퀴스트(Nyquist) 입력인 50 MHz까지 증가하는 동안 54 dB 이상의 SNDR과 68 dB 이상의 SFDR(spurious-free dynamic range)을 유지하였다. 입출력단의 패드를 제외한 칩 면적은 3.6 $mm^2$(= 1.8 mm ${\times}$ 2.0 mm)이며, 최대 동작 주파수인 120 MHz 클럭에서 측정된 전력 소모는 208 mW이다.

Keywords

References

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