Op Amp circuits (Part 3) - Department of Electrical Engineering

76 Pages·2015·1.11 MB·English

EE101: Op Amp circuits (Part 3)
M. B. Patil
[email protected]
www.ee.iitb.ac.in/~sequel
DepartmentofElectricalEngineering
IndianInstituteofTechnologyBombay
M.B.Patil,IITBombay
Alow-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthelow-frequency
componentv1(t)andremovethehigh-frequencycomponentv2(t).
Ahigh-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthehigh-frequency
componentv2(t)andremovethelow-frequencycomponentv1(t).
Therearesomeothertypesoffilters,aswewillsee.
v LPF vo=v1
v HPF vo=v2
Introduction to filters
Considerv(t)=v1(t)+v2(t)=Vm1sinω1t+Vm2sinω2t.
1
v
1 v
v
2
0

−1
0 5 10 15 20 0 5 10 15 20
t (msec) t (msec)
M.B.Patil,IITBombay
Ahigh-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthehigh-frequency
componentv2(t)andremovethelow-frequencycomponentv1(t).
Therearesomeothertypesoffilters,aswewillsee.
v HPF vo=v2
Introduction to filters
Considerv(t)=v1(t)+v2(t)=Vm1sinω1t+Vm2sinω2t.
1
v
1 v
v2 v LPF vo=v1
0

−1
0 5 10 15 20 0 5 10 15 20
t (msec) t (msec)
Alow-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthelow-frequency
componentv1(t)andremovethehigh-frequencycomponentv2(t).
M.B.Patil,IITBombay
Therearesomeothertypesoffilters,aswewillsee.
Introduction to filters
Considerv(t)=v1(t)+v2(t)=Vm1sinω1t+Vm2sinω2t.
1
v
1 v
v2 v LPF vo=v1
0

v HPF vo=v2

−1
0 5 10 15 20 0 5 10 15 20
t (msec) t (msec)
Alow-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthelow-frequency
componentv1(t)andremovethehigh-frequencycomponentv2(t).
Ahigh-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthehigh-frequency
componentv2(t)andremovethelow-frequencycomponentv1(t).
M.B.Patil,IITBombay
Introduction to filters
Considerv(t)=v1(t)+v2(t)=Vm1sinω1t+Vm2sinω2t.
1
v
1 v
v2 v LPF vo=v1
0

v HPF vo=v2

−1
0 5 10 15 20 0 5 10 15 20
t (msec) t (msec)
Alow-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthelow-frequency
componentv1(t)andremovethehigh-frequencycomponentv2(t).
Ahigh-passfilterwithacut-offfrequencyω1<ωc <ω2 willpassthehigh-frequency
componentv2(t)andremovethelow-frequencycomponentv1(t).
Therearesomeothertypesoffilters,aswewillsee.
M.B.Patil,IITBombay
Allcomponentswithω<ωc appearattheoutputwithoutattenuation.
Allcomponentswithω>ωc geteliminated.
(Notethattheideallow-passfilterhas∠H(jω)=1,i.e.,H(jω)=1+j0.)
V(jω)i LPF V(jω)o
ω ω
0 0
ω ω
c c
Ideal low-pass filter
1
vi(t) H(jω) vo(t) H(jω)
0 ω
0
ω
c
Vo(jω)=H(jω)Vi(jω).
M.B.Patil,IITBombay
(Notethattheideallow-passfilterhas∠H(jω)=1,i.e.,H(jω)=1+j0.)
Allcomponentswithω<ωc appearattheoutputwithoutattenuation.
Allcomponentswithω>ωc geteliminated.
Ideal low-pass filter
1
vi(t) H(jω) vo(t) H(jω)
0 ω
0
ω
c
V(jω)i LPF V(jω)o
ω ω
0 0
ω ω
c c
Vo(jω)=H(jω)Vi(jω).
M.B.Patil,IITBombay
Ideal low-pass filter
1
vi(t) H(jω) vo(t) H(jω)
0 ω
0
ω
c
V(jω)i LPF V(jω)o
ω ω
0 0
ω ω
c c
Vo(jω)=H(jω)Vi(jω).
Allcomponentswithω<ωc appearattheoutputwithoutattenuation.
Allcomponentswithω>ωc geteliminated.
(Notethattheideallow-passfilterhas∠H(jω)=1,i.e.,H(jω)=1+j0.)
M.B.Patil,IITBombay
High−pass
1
)
ω
H(j
0 ω
0
ω
c
Band−pass Band−reject
1 1
) )
ω ω
H(j H(j
0 ω 0 ω
0 0
ω ω ω ω
L H L H
Ideal filters
Low−pass
1
)
ω
H(j
0 ω
0
ω
c
M.B.Patil,IITBombay
Band−pass Band−reject
1 1
) )
ω ω
H(j H(j
0 ω 0 ω
0 0
ω ω ω ω
L H L H
Ideal filters
Low−pass High−pass
1 1
) )
ω ω
H(j H(j
0 ω 0 ω
0 0
ω ω
c c
M.B.Patil,IITBombay