應用於醫用超音波影像前端接受電路之研製

由於安全性及低成本的考量，超音波影像一直是醫師在臨床診斷中的一大利器。由於超音波影像系統需要相當高的動態範圍及信噪比，一般都使用III-V半導體製程和BiCMOS製程進行前端接受器的設計。近年來隨著MEMS技術的進步，已有許多研究團隊開始使用標準的CMOS製程研製超音波探頭。為了實現單晶片系統整合以降低設計複雜度並降低成本，開發使用CMOS製程的超音波前端接受器是必要的。在本論文中，多種的電路架構與技巧被提出與實現以提高系統的動態範圍並提升電路的線性度。本論文以六個章節所構成。第一章會對超音波成像系統進行基本的介紹，第二章則對超音波前端接收器的設計流程進行說明。第三章提出一個以0.18-um標準互補式金氧半導體製程實現的超音波前端接收器。並整合類比數位轉換器以提供數位訊號輸出。為了提供足夠的動態範圍，本接收器提供了三種增益模式，並使用指數壓控放大器提供進行時間增益補償的可能性。第四章討論在進行單晶片系統整合及多通道設計時會遇到的訊號干擾問題。本章提出一種基底雜訊消除技巧以降低訊號受到基底雜訊影響的程度，並且使用65奈米CMOS製程實作一個四通道的超音波前端接收器以驗證效果。為了降低電路的複雜度及面積，提出了一個以單一放大器同時實現可調增益放大器及濾波器的功能的全差動操作可程式化增益濾波器。第五章包括一個高線性度的超音波前端接收器之設計與實作結果。藉由使用共閘共源低雜訊放大器，可將訊號直接轉為全差動操作。為了提高前端接受器的輸出範圍及線性度，提出一種新穎的電容耦合式可程式化增益放大器，利用切換回授電容的方式以達到改變增益的效果。最後，在第六章會進行本論文的總結。

關鍵字

超音波影像；前端接收電路；超音波接收電路；可調增益放大器

並列摘要

In diagnostic medicine, ultrasound imaging is one of the most widely used diagnostic tools due to its safety and relatively low cost. To facilitate system-on-chip implementation to minimize the cost, the development of CMOS ultrasound receiver front-end is essential. In this thesis, several architectures and circuit techniques are presented to increase the dynamic range and the linearity of the receiver. The first chapter introduces the fundamentals of an ultrasound imaging system, including a brief introduction to the whole system and the architecture of the receiver. Chapter 2 illustrates the challenges in ultrasound receiver design and the link budget calculation is demonstrated for system optimization. In Chapter 3, a highly integrated ultrasound receiver front-end is implemented by using a standard 0.18-um CMOS process. The high speed analog-to-digital converter is integrated in this design to provide digital data output. Moreover, in order to increase the dynamic range, the proposed front-end circuit provides three gain modes and a linear-in dB variable gain amplifier is employed to perform time gain compensation technique. In chapter 4, the signal integrity problem in system-on-chip and multichannel designs will be discussed. In this chapter, a feed-forward substrate noise cancellation scheme is proposed to suppress substrate crosstalk phenomenon. A quad-channel ultrasound receiver front-end is demonstrated in 65-nm CMOS process. In order to reduce the complexity and area of the circuit, a fully-differential programmable gain anti-aliasing filter is proposed by using a single OPAMP. The design and experimental results of a high-linear ultrasound receiver front-end are illustrated in Chapter 5. By using a CG-CS balun low-noise amplifier, the received single-ended signal can be converted to differential signal directly. To improve the linearity and output swing range, a capacitively-coupled programmable gain amplifier is proposed. The gain of the amplifier can be adjusted by controlling the switched-capacitors.

並列關鍵字

ultrasound ； receiver front-end ； CMOS ； ultrasound imaging ； variable gain amplifier ； time gain compensation

參考文獻

[5] B. Herman and G. Harris, Models and regulatory considerations for the transient temperature rise during diagnostic ultrasound pulses. Ultrasound in Medicine and Biology, 28(9):1217-1224, 2002.

[6] T. Tsukada, Y. Hashimoto, K. Sakata, H. Okada and K. Ishibashi, “An on-chip active decoupling cirucit to suppress crosstalk in deep-submicron CMOS mixed-signal SoCs ,” IEEE J. Solid-State Circuits, vol. 40, pp. 67-79, Jan. 2005.

[7] J. P. Z. Lee, F. Wang, A. Phanse and L. C. Smith, “Substrate cross talk noise characterization and prevention in 0.35μm CMOS technology,” in Proc. IEEE Custom Integr. Circuit Conf., May 1999, pp. 479-482.

[8] H. -M. Chao, W.-S. Wuen and K. -A. Wen, “An active guarding circuit design for wideband substrate noise suppression,” IEEE Transactions on Microwave Theory and Techniques, vol. 56, no. 11, pp. 2609-2619, Nov. 2008.

[9] P. Orsatti, F. Piazza and Q. Huang, “A 71-MHz CMOS IF-baseband strip for GSM,” IEEE J. Solid-State Circuits, vol. 31, pp. 104-108, Jan. 2000.

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應用於醫用超音波影像前端接受電路之研製

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