freqanalysisamplifierpartI

# freqanalysisamplifierpartI - (Chapter3:section3.11 ECE412...

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Adaptive Integrated Microsystems Frequency analysis of signal stage amplifiers  (Chapter 3: section 3.11) ECE 412 Introduction to mixed-signal circuits (Fall 2007) Class website: http://www.egr.msu.edu/classes/ece412/shantanu

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Adaptive Integrated Microsystems Conceptual interpretation of poles and zeros Poles are associated with number of internal nodes that need to be charged. This circuit has three poles. But no zeros !!! Zeros are associated by different ways in which a signal can nullify itself at the output. The circuit has one zero. REMEMBER: Paths should have different delays to nullify.
Adaptive Integrated Microsystems Location of poles and zeros Frequency analysis of most analog circuit can be mapped onto three basic topologies. ) ( s I R out V C ) 1 ( ) ( ) ( RCs s RI s V out + = A current source charging a parallel combination of resistance and capacitance leads to a pole. Location of the pole is dependent on R and C. RC s 1 - = This is equivalent to frequency RC p 1 = ϖ

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Adaptive Integrated Microsystems Location of poles and zeros ) ) )( || ( 1 ( )] ( ) ( )[ || ( ) ( 2 1 2 1 1 2 2 1 s C C r r s I s I r r s V out + + - = The output voltage is dependent on the difference of the two currents. The location of the pole is dependent on the total resistance at the output node and total capacitance at the output node. I1(s) = I2(s) leads to a zero. ) ( 2 s I ) ( s V out dd V ) ( 1 s I 1 r 2 r 2 C 1 C ) )( || ( 1 2 1 2 1 C C r r s + - =
Adaptive Integrated Microsystems Miller’s theorem ) 1 ( 1 v F A C Z - = F v F C A C Z - = - ) 1 ( 1 2 Input capacitance Output capacitance REMEMBER that the feedback capacitor could lead to a zero if there is a delay between two paths. A feedback capacitor can be decomposed into un-coupled impedance.

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Adaptive Integrated Microsystems AC model for MOS transistors Small signal Model Parasitic capacitors Small signal AC model pF C pF C pF C db gd gs 02 . 0
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freqanalysisamplifierpartI - (Chapter3:section3.11 ECE412...

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