1EE105 - Fall 2005Microelectronic Devices and CircuitsLecture 13Two-Port ModelsCommon-Source Amplifiers Revisited2AnnouncementsHomework 6 due todayNo labs this week Lab 5 next weekReading: Chapters 9.4, 8 (MOS only)Midterm 1 on ThursdayOctober 13, 6:30-8pm, SibleyReview session todayOctober 11, 6:30-8pm, 277 CoryNo office hour next MondayPlease come and see me after the lecture on Tuesday3Lecture MaterialLast lectureMOS current sourcesThis lectureGeneralized two-port modelsCommon-source amplifier (again)25Maximize Gain of CS AmpIncrease gm(more current)Increase RD(free? Don’t need to dissipate extra power)Limit: Must keep the device in saturationFor a fixed current, the load resistor can only be chosen so largeTo have good swing we’d also like to avoid getting to close to saturation||vmDoAgR r=−,DSDDDDDSsatVVIRV=−>26Current Source SupplySolution: Use a current source!Current independent of voltage for ideal source 27CS Amp with Current Source Supply228Load Line for DC BiasingBoth the I-source and the transistor are idealized for DC bias analysis29Two-Port ParametersFrom currentsource supplyinR =∞||out o ocRrr=mmGg=30P-Channel CS AmplifierDC bias: VSG= VDD– VBIAS sets drain current –IDp= ISUP31Two-Port Model ParametersSmall-signal model for PMOS and for rest of
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