Large-Signal OperationNonlinear curves.LinearsegmentsMaximum value of input differential voltagesVid=↓VTas a small-signal amplifiercan be used as a fast currentVid = 4V ~100mVswitchEnlarge the linear segment by including equalresistance Re in series with the emittersMicroelectronic Circuits
Microelectronic Circuits Large-Signal Operation ⚫ Nonlinear curves. ⚫ Linear segments. ⚫ Maximum value of input differential voltages as a small-signal amplifier can be used as a fast current switch ⚫ Enlarge the linear segment by including equal resistance Re in series with the emitters. id VT v 2 1 = v V mv id = 4 T 100
Large-SignalOperationCic2/lici/lR1.0IR,=20VOwCUcC0.8IR,=10VTIR=0QQOUB2UBIO0.60.4IR=0IR,=10V0.2IR,=20V0Ua/VT8122024041624-20-16-12-8-a(b)aThetransfercharacteristicsoftheBJTdifferentialpair(a)canbelinearizedbyincludingresistancesintheemitters.Microelectronic Circuits
Microelectronic Circuits Large-Signal Operation The transfer characteristics of the BJT differential pair (a) can be linearized by including resistances in the emitters
6.2Small-signal operation of theBJTdifferential amplifierVccRoRgmVce-Re-gmReo(Vcc-=Re)+gmRe2gmReueo02十+WiVidWidUBEIBLUBE2R2PPO<2VUidQlgm2VThe currents and voltages in the differential amplifier when a smalldifferential input signal Vid is applied.MicroelectronicCircuits
Microelectronic Circuits 6.2 Small-signal operation of the BJT differential amplifier The currents and voltages in the differential amplifier when a small differential input signal vid is applied
Small-Signal Operation-2RRVTVTZIe2a2raQVdgmYVid22re0A simpletechniquefor determiningthe signal currents in a differential amplifierexcited by a differential voltage signal vid dc quantities are not shown.MicroelectronicCircuits
Microelectronic Circuits A simple technique for determining the signal currents in a differential amplifier excited by a differential voltage signal vid; dc quantities are not shown. Small-Signal Operation 2 2 2 2 d m e d c e e d e T E T e v g r v i i r v r I V I V r = = = = = =
Small-Signal Operation2+R+RaRAR>A differential920+R0+20+RVamplifier with emitter2B+1)C+Rresistances.十>Only signalquantities are shownUid(in color).RT+RMicroelectronic Circuits
Microelectronic Circuits Small-Signal Operation ➢A differential amplifier with emitter resistances. ➢Only signal quantities are shown (in color)