不同电流反馈对高性能的两级CMOS放大器共模稳定性
Abstract摘要
稳定的全差分算法（FD）两级放大器提出了在图2（c）具有快速、保证无闩锁、低偏移的同时提供一些在功耗增加简单的跟踪补偿。电源电压范围从0.7到1.2 V的地方不断增加的需求对模拟电源预算空间高效利用亚微米工艺。共模（CM）偏移（VOSCM），差分偏移（VOS），和noiseerode动态范围。共模（CM）偏移是一个经常被忽略的误差贡献共模反馈放大器。一厘米的放大器的优良品质：快速解决，无锁定操作下的瞬态条件下，，低功耗，低贡献低噪音，VOSCM FD的电路，即流水线ADC。众所周知，电流反馈可以快速，只有经由过程[1,2]的电流增益带宽的限制。该共模电流放大器在图2（c）避免了闭锁状态的同时保持共模反馈（CMFB）环路稳定性和简化共模反馈补偿。
共模偏置；差分偏移；双级放大器；共模放大器
—A robustmethod for stabilizing fully differential (FD) two stage amplifiers is presented inFig.2(c) which is fast, guaranteed latch free, low offset while offering simpler tracking of compensation with some increase in power dissipation. Submicron processes with supply voltages ranging from 0.7 to 1.2 V place an ever increasing demand on efficient use of analog supply budget headroom. Common mode (CM) offset (VOSCM), differential offset (Vos), andnoiseerode dynamic range. Common mode (CM) offset is an often overlooked error contributionof the CM feedback amplifier. The desirable qualities of a CM amplifier are: fast settling, latch up free operation under all transient conditions while being low power,contributing lownoise, low VOSCM to FD circuits, i.e. pipelined ADCs. It is widely known that current feedback can be fast,limited only by the current gain bandwidth of the process[1,2]. The proposed CM current amplifier in Fig. 2(c) avoids latching states while maintainingcommon mode feedback (CMFB) loop stability and simplifying CMFB compensation.
I. INTRODUCTION介绍
Fully differential two stage amplifiers are widely used as a result of increased dynamic range, attenuation of CM noise, reduced harmonic distortion, and increased bandwidth[2,3]. The major disadvantage of two stage fully differential circuits is; their potential for latch up, the need for a fast CMFB circuit to set the CM output voltage, the added noise and the VOSCM contribution to system design considerations. The CMFB amp senses the output CM voltage from the FD amplifier and using negative feedback sets the CM voltage of the differential amplifier output to a CM reference voltage, VREFCM. In this Letter, we investigatewide bandCM amplifiersfor the highlydesirable two stage amplifierinFig. 1,which haspotential positive feedback and latch up[4,5].Existing solutions reported as latch up free[4,6],can add a degree of difficultyin compensationand/or in achieving necessary desired CM amplifier bandwidth while maintain low VOSCM. Problems arises from the observation that both CM gain and FD gain share the identical 1st and 2nd stages and compensationbut with different transconductances (FD differential and CM pair) with an added CM gain stage. This difficulty is exacerbated when FD amplifier bandwidth approaches a processes unity current gain bandwidth (fTA). The proposed CMFB current amplifier (CMCA) addressesthese difficulties using current feedback (M1CM) across the bandwidth of interest with the FD amplifier in context.
II. CM LATCH UP, STABILITY AND OFFSET
III. CM TOPOLOGY COMPARISON
References文献
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Guanglei An received the B.S. degree in communication engineering from Jilin University in 2004 and M.S. degree inn electronics engineering from Chongqing University of Posts and Telecommunications in 2007. He is currently working toward his Ph.D degree at Oklahoma State University in the MSVLSI design group. His research interests include low power analog and mixed-signal VLSI for biomedical applications.
Chris Hutchens (S‘71-M’73) received the B.S. and M.S. degrees in electrical engineering from South Dakota State University. He received the Ph.D. degree from the University of Missouri, in 1979. In 1986 he joined the faculty of the School of Electrical and Computer Engineering at the Oklahoma State University. His current research interests include: high temperature mixed signal VLSI, device modeling, subthreshold mixed signal CMOS for biomedical instrumentation and RFIDs, and acoustic transducer design. Dr. Hutchens is an experienced mixed signal analog designer. He has multiples years’ experience in mixed signal electronics for extreme temperature and medical markets and is a Certified Clinical Engineer. He has served as a member of the Board of Clinical Engineering Certification.
Robert L. Rennaker II received the B.S, M.S. and Ph.D. degrees in biomedical engineering from Arizona State University (1997, 2001, 2002). In 2002 he joined the faculty of the School of Aerospace and Mechanical Engineering at The University of Oklahoma. In 2010 he joined the faculty of the Erik Jonnson School of Engineering and Behavioral and Brain Sciences at The University of Texas at Dallas. His current research includes the development of neural interfaces, systems level neuroscience, neural plasticity and immune response to implanted materials.
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