CEamplifier is notproper for usingas apoweramplifieric直流负载线交流负载线BOuy0OUcEQUcEo+IcoR' Vcc ucE(b)aDCsupplypower:IcQVcc,theareaofABCOco(Rc // R,)/ /2Rcpower:IcQURc,theareaofQBCDCollectordissipationpower:lcUcEQ,theareaofAQDOPomLoad power:MicroelectronicCircuits
Microelectronic Circuits CE amplifier is not proper for using as a power amplifier ( ) 2 1 2 ( // )/ 2 ' ' 2 ' L CQ CQ L CQ om CQ C L R I I R I P I R R = = DC supply power: ICQVcc , the area of ABCO Rc power: ICQURc， the area of QBCD Collector dissipation power: ICQUCEQ， the area of AQDO Load power:
Class A Output Stage+Vcc。= V -VBEIQU1o+Vomax = Vcc -VcE1satUBEItElOO= -IR,VominRRorOQ文Vomin =-Vcc +VVCE2satVccMicroelectronic Circuits
Microelectronic Circuits Class A Output Stage o CC CE sat o L o CC CE sat o I BE v V V v IR v V V v v v min 2 min max 1 1 or = − + = − = − = −
UoA(Vce-VcEIsat)0UVBEI-IRL(-Vcc+VcE2sat)Figure14.3 Transfer characteristic of the emitter follower.This linearcharacteristic is obtained by neglecting the change in VBEi with iz. ThemaximumpositiveoutputisdeterminedbythesaturationofOi.Inthenegative direction, the limit of the linear region is determined either by Qturning off or by Q2 saturating, depending on the values of I and Rz.MicroelectronicCircuits
Microelectronic Circuits Figure 14.3 Transfer characteristic of the emitter follower. This linear characteristic is obtained by neglecting the change in vBE1 with iL . The maximum positive output is determined by the saturation of Q1 . In the negative direction, the limit of the linear region is determined either by Q1 turning off or by Q2 saturating, depending on the values of I and RL