Recent Advances on the Design of High-Gain Wideband Operational Transconductance Amplifiers

Feed-forward techniques are explored for the design of high-frequency Operational Transconductance Amplifiers (OTAs). For single-stage amplifiers, a recycling folded-cascode OTA presents twice the GBW (197.2 MHz versus 106.3 MHz) and more than twice the slew rate (231.1 V/μs versus 99.3 V/μs) as a c...

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Bibliographic Details
Published in:VLSI Design 2009-01, Vol.2009 (2009), p.26-36
Main Authors: Assaad, Rida, Silva-Martinez, Jose
Format: Article
Language:English
Subjects:
Design specifications
Simulation
Spectrum allocation
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Summary:Feed-forward techniques are explored for the design of high-frequency Operational Transconductance Amplifiers (OTAs). For single-stage amplifiers, a recycling folded-cascode OTA presents twice the GBW (197.2 MHz versus 106.3 MHz) and more than twice the slew rate (231.1 V/μs versus 99.3 V/μs) as a conventional folded cascode OTA for the same load, power consumption, and transistor dimensions. It is demonstrated that the efficiency of the recycling folded-cascode is equivalent to that of a telescopic OTA. As for multistage amplifiers, a No-Capacitor Feed-Forward (NCFF) compensation scheme which uses a high-frequency pole-zero doublet to obtain greater than 90 dB DC gain, GBW of 325 MHz and better than 70∘ phase margin is discussed. The settling-time- of the NCFF topology can be faster than that of OTAs with Miller compensation. Experimental results for the recycling folded-cascode OTA fabricated in TSMC 0.18 μm CMOS, and results of the NCFF demonstrate the efficiency and feasibility of the feed-forward schemes.
ISSN:1065-514X
1563-5171
DOI:10.1155/2009/323595