Operational Amplifiers, OP-AMPS
The Ideal OP-AMP
Inputs
Ideal OP-AMP with Power Supplies
No terminal of the OP-AMP is physically connected to ground.
Functions and Characteristics of the Op-Amp
1. The Op-Amp senses the voltage difference at its
two inputs
Bipolar Junction Transistors.
DEVICE STRUCTURE AND PHYSICAL OPERATION
Simplified Structure and Modes of Operation
npn transistor
The transistor consists of two pn junctions, the EBJ
and the CBJ
BJT Modes of Operation
Mode
EBJ
CBJ
Cutoff
Reverse
Reverse
Ac
SINGLE-STAGE MOS AMPLIFIERS
The Basic Structure
EXERCISE 4.3
V DD = VSS = 10 V , I = 0.5 mA, RG = 4.7 M, R D = 15 15k, Vt = 1.5 v, and k n ' (W / L) = 1 mA / V 2
Find VOV , VGS , VG , VS , V D , g m and r0 assume V A = 75 V
Characterizing Amplifiers
Does
BIASING IN MOS AMPLIFIER CIRCUITS
Biasing by Fixing VGS
The Bias point depends too much on the particular
transistor selected.
Biasing by Fixing VG
Resistor RS introduces
feedback and changes VGS
if I D changes as when
transistors are interchanged.
VG = V
Example 4.5
Analyze the circuit to determine
the voltage at all nodes and the
current trough al branches. Let
Vt = 1 V and
k n ' (W / L) = 1 mA / V 2 . Neglect the
channel length Modulation.
Example 4.6
Design the circuit so that the transistors operate i
CURRENT-VOLTAGE CHARACTERISTICS
We will present the current voltage characteristic for DC to low frequency operation of the Enhancement type
MOSFET.
Circuit Symbol
Figure 4.10 (a) Circuit symbol for the n-channel
enhancement-type MOSFET. (b) Modified circ
MOS Field-Effect transistors (MOSFETs)
MOSFETS BJTs are three terminal devices, they are more useful than two terminal devices, and they could be used in:
Amplification,
Logic circuits and
Memories
The MOSFET has become the most widely used electronic dev
Physical Operation of Diodes
Band Theory of Solids
Some material from: http:/hyperphysics.phy-astr.gsu.edu/hbase/solids/intrin.html
Doped Semiconductors
Diffusion and Drift
Diffusion
J p = qD p
J n = qDn
dp
dx
dn
dx
J ( A / cm 2 )
n and p (atoms / cm 3)
D
Modeling The Diode Forward Characteristic
OPERATION IN THE REVERSE BREAKDOWN REGION ZENER DIODES Specifying and Modeling The Zener Diode
Use of the Zener Diode as a Shunt Regulator
Temperature Coefficient
v Z < 5 V TC < 0; TC (mV ) ; v Z > 7 V TC > 0; TC
EXCERSISE 3.9
MODELING THE DIODE FORWARD CHARACTERISTIC Graphical Analysis Using The Exponential Model
Iterative Analysis Using The Exponential Model
VDD = 5 V, R= 1 k ohm, ID= 1 mA @ 0.7 V VD hanges .1 V per every decade change in current
The Piecewise-L
THE IDEAL DIODE
Current Voltage Characteristics
The Recrifier
Exercise 3.1
For circuit (a) find v 0 versus v .
The transfer characteristic.
Exercise 3.2
For circuit a) sketch the waveform of v D .
Exercise 3.3
v I peak is 10 V, R L = 1 k ohm , find i D pe
The Inverting Integrator
Effect of DC imperfections
EXAMPLE 2.7 Miller integrator R= 10K ohm, C = 10 nF Add RF 1M ohm and compare.
The Op Amp Differentiator
LARGE-SIGNAL OPERATION OF OP-AMPS
Output Voltage Saturation
Op-Amp with Rated Output Voltage of 13V
a)
b)
c)
d)
For Vp = 1 and RL = 1kohm, specify the signal resulting at the output of the amplifier.
For Vp = 1.5 and RL = 1kohm, specify the signal resulti
DIFFERENCE AMPLIFIERS
Also known as differential amplifiers. Ideally responds to the differential voltage and rejects the common mode
voltage. Practical circuits will have a combination of both modes.
v 0 = Ad v Id + Acm v Icm
The efficacy is usually meas
Bipolar Junction Transistors Characteristics.
Biasing Using a Collector to Base Feedback Resistor
VCC = I E RC + I B R B + V BE
IE
R B + V BE
+1
VCC VBE
IE =
RC + R B /( + 1)
VCC = I E RC +
Conceptual circuit for measuring the iC VCB characteristic (comm