Device Level Noise Modeling excerpts from Gray Meyer text Analysis and Design of Analog Integrated Circuits John Wiley 1 shot noise Johnson noise ignore both of these 2 Comments Voltage source representation is used for Series connected resistors Current source representation is used for Parallel connected resistors discussion in class 3 Z frequency Red Johnson Blue Shot basically input RC of the circuit Let s look at just ONE TERM RS Basic gain expression SQUARED rb Z Voltage divider expression at the input SQUARED Transfer Function for Johnson Noise Johnson Noise for two resistors in series per unit BW 4 Additional Noise Sources Bias Resistors parallel Shunt Shunt RF parallel R1 R2 RF RF Analysis One needs to determine the transfer function for each noise source to the output and then SQUARE it in order to get the respective POWER relationship Typical numbers IC low R s a bit high dominant term resistors not IB dominant term IC and not resistors If IC increases 10X becomes 8 8x10 15 5 Determined by BW 6 Gain Expression Transfer Function SQUARED 7 Rough Approximation of Open Loop LNA Shunt Shunt Feedback At output Req RL RF At input make ONE equivalent noise resistor RS eq that is in series with rb The transfer function used to refer output noise to the input DOES NOT CHANGE basically the parallel resistors R1 R2 RF are basically now part of new Z Req RS eq rb Z R2 eq Z R2eq Req Modified per above discussion see above comment about SQUARED 8 9 Mission Possible in 1hr a reminder that Mid Term will ask you to do Mission Possible In Class and in finite time SPAM Receiver TL M M O I 50 j122 1 5K and in your real design you ll need to add C series connected 9V TL 70K 1 5K 1 4Vdc CBIG tT en k an Design Q1 140 2V I 20K 50 j122 C l va ui Eq M MO L Antenna M LNA equiv I L Cparallel RL parallel vs 10 Blocks for SPAM Receiver Antenna XO Lab 2 Decoding BNC to ANT LNA Lab 3 Mixer SA 612 IF Amp PLL LM 565 BNC to Speaker Lab 1 Lab 4 11
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