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Analyzing of CDTA using a New Small Signal Equivalent Circuit and Application of LP Filters

새로운 소신호 등가회로를 활용한 CDTA의 해석 및 저역통과 필터설계

  • Bang, Junho (Department of IT Applied System Engineering, Smart Grid Research Center, Semiconductor Design Education Center, Chonbuk National University) ;
  • Song, Je-Ho (Department of IT Applied System Engineering, Smart Grid Research Center, Semiconductor Design Education Center, Chonbuk National University) ;
  • Lee, Woo-Choun (Department of IT Applied System Engineering, Smart Grid Research Center, Semiconductor Design Education Center, Chonbuk National University)
  • 방준호 (전북대학교, IT응용시스템공학과, 스마트그리드연구센터, 반도체설계교육센터) ;
  • 송제호 (전북대학교, IT응용시스템공학과, 스마트그리드연구센터, 반도체설계교육센터) ;
  • 이우춘 (전북대학교, IT응용시스템공학과, 스마트그리드연구센터, 반도체설계교육센터)
  • Received : 2014.10.31
  • Accepted : 2014.12.11
  • Published : 2014.12.31

Abstract

A CDTA (current differencing transconductance amplifier) is an active building block for current mode analog signal processing with the advantages of high linearity and a wide frequency bandwidth. In addition, it can generate a stable voltage because all the differencing input current flows to the grounded devices. In this paper, a new small signal equivalent circuit is proposed to analyze a CDTA. The proposed small signal equivalent circuit provides greater precision in analyzing the magnitude and frequency response than its previous counterparts because it considers the parasitic components of the input, internal and output terminal. In addition, observations of the changes made in various devices, such as the resistor (Rz) confirmed that those devices heavily influence the characteristics of CDTA. The designed parameters of the proposed small signal equivalent circuit of the CDTA provides convenience and accuracy in the further design of analog integrated circuits. For verification purposes, a 2.5 MHz low pass filter was designed on the HSPICE simulation program using the proposed small signal equivalent circuit of CDTA.

CDTA는 전류모드로 아날로그 신호처리를 수행하는 능동회로로써 높은 선형성과 넓은 주파수 대역폭을 갖는 장점을 가지고 있다. 또한 입력 차동전류가 모두 접지된 임피던스 소자로 흐르게 되어 안정적인 동작을 수행하도록 한다. 본 논문에서는 CDTA를 해석하기 위해 새로운 소신호 등가회로를 제안한다. 제안된 소신호 등가회로는 입력과 내부단자 및 출력단자의 기생성분이 고려되어 크기 및 주파수 특성이 기존회로보다 정밀하게 분석될 수 있다. 제안된 소신호 회로를 활용하여 다양한 파라미터의 변화에 의하여 특성변동을 관찰한 결과, 저항(Rz) 등 특정한 값이 CDTA의 특성에 큰 영향을 주게 되는 것도 확인되었다. 본 논문에서 검증된 소신호 등가회로의 설계 파라미터는 CDTA 아날로그 회로와 그 응용회로를 설계하는데 편리성과 정확성을 제공할 수 있음을 보였다. 본 논문에서 제안된 CDTA 소신호등가회로를 이용하여 2.5MHz 저역통과 필터를 설계하였고 HSPICE 시뮬레이션을 통하여 그 유용성을 검증하였다.

Keywords

References

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