The Design Of Fully Differential Operation Amplifier

Recently, the demand of electron product epically semiconductor Integrate circuit chip are becoming wider and wider, and requirements on performance are getting higher too. Operation amplifier act as an integrity part in many analog systems and mix digital systems, it's also a basic cell of these systems, so it take up a very important place in design and optimize. Improvement of the operation amplifier's performance can highly improve the capability of the entire system. At the present time, research inside and outside mainly focused on application of high speed signal dispose and low power consummation, and these are filed we can break through.This article begin with the keystone of CMOS operation amplify circuit, and introduced the elements and main application of operation amplifier, for example adder and integrph.Second, this article analysis the familiar fully differential amplify circuit structure, including basic fully differential structure, folded-casecod, telescopic structure, then made a basic analysis of the structure and performance of common-mode feedback, these makes the foundation of the design.Third, set up the performance target of the operation amplifier, the circuit should have a high open-loop gain and high unit gain bandwidth. Considering these parameters, I designed a two stage telescopic fully differential operation amplifier.After the design of the circuit, I set the parameters of the devices which appear in the circuit particularly. Parameters such as DC gain, phase margin and bandwidth are analyzed use the HSPICE software. The result shows the DC gain of the operation amplifier is 83.4dB, and its unit gain bandwith is 55.3MHz, these satisfied the demand of this design.Finally, analysis the layout design rules and the relevant part of the circuit layout element, the layout of the fully differential operation amplify has been designed use Vitusuo form the cadence company layout design tools.