Upload
sauravabidrahman
View
10
Download
1
Embed Size (px)
DESCRIPTION
Amplifier
Citation preview
MULTISTAGE AMPLIFIER Cascaded Connection Output of one stage is connected to the input of another stage.
Amplifier 1Gain = AV1
Amplifier 2Gain = AV2
Overall gain AV = VO2 / Vin 1 = Av1 AV2
Cascaded BJT Amplifier
Draw the (i) Input and (ii) output voltage waveshape for different values of Vi (a) 25V (b) 1mV (c) X mV, where X is last two digits of your Roll No.
Cascaded FET Amplifier
AV1 = -gm1RD1
AV2 = -gm2RD2
Overall gain AV1AV2 = (-gm1RD1)(-gm2RD2)
Input Impedance Zin = RG1
Output Impedance ZO = RD2
Darlington Connection
Overall = 1 2
Two transistors are connected in such a way that emitter current of one is fed to the base of another, so that the overall current gain is the product of their individual current gains.It is also known as superbeta transistorIE1 = (1+ 1 ) IB1 IE2 = (1+ 2 ) IB2 IE2 = (1+ 2 ) (1+ 1 ) IB1IE2 2 1 IB1
2N999 npn darlington transistorVBE = 1.8V at IC = 100mAD = 4000 at IC = 10mA D = 7000 at IC = 100mAMaximum D = 70,000 at IC = 100mA
DC bias of Darlington CircuitVCC
DC bias of Darlington Circuit18VVBE = 1.6VD =8000
AC analysis of Darlington Circuit
AC Input Impedance of Darlington CircuitD =8000ri = 5K
AC Current Gain of Darlington Circuit
AC Output Impedance of Darlington Circuit
AC Voltage gain of Darlington Circuit
Summery of Darlington connectionSuper beta transistor, D = 1 2.High current gain, can amplify very small signal.Increased input impedance.Reduced output impedance.Unity voltage gain.
CMOS CircuitComplementary Metal Oxide Semiconductor Field Effect TransistorVi = 0VVo = 5VVDD = 5V Vi = 5VVo = 0VVDD = 5VCMOS is used as an inverter
Current sourceRL = 2RL = 2KVDD = 24V
BJT Current source
BJT - Zener Current source
Current Mirror Circuit