Ideal Op Amp
Ideal Op Amp
Ideal Op Amp
Ideal Op Amp
Real Op Amp
it
produces
the
high
input
high
input impedance
want
high
input
doesn't
disturb
the
input
impedance.
Even
amps,
such
MOSFETs,
as
have
in
the
order of teraohms, it is
still finite.
Impedance
zero
output
impedance. always
have
some
impedance,
in
circuit
present
in
component
of
higher 75.
be
independent
of
Outside
good
across
frequencies.
In an ideal op amp, if no A real op amp will
voltage is applied to the have slight offset even
inverting and noninverting if the voltage applied
Zero
Input input pins, the op amp will to the pins are the
Voltage Offset
pin.
DC voltage supplied to an
op amp.
Output
This
by
is
the
amp.
OP AMP Parameters
Operational Amplifiers An Introduction:
to
perform
mathematical
operations
like addition,
A very high open loop voltage gain AO = 105 for d.c. and lowfrequency a.c., which decreases with frequency increase
2.
A very high input impedance (Ri = 106 to 1012) so that the input
voltage is passed on to the op amp with little loss
3.
V2
V1,
Vo
The ideal opamp is a differential input, single ended output device. It has
the following characteristics
1. Infinite input resistance [Ri = Infinity]
2. Zero output resistance [RO = 0]
3. Infinite voltage gain [AV = Infinity]
4. Infinite bandwidth [BW = Infinity]
5. Infinite Common Mode Rejection Ratio
6. Infinite slew rate
7. Zero offset [ ie,V1 = V2 , VO =0]
8. Characteristics do not drift with temperature
Op amp Parameters:
Input offset voltage
Input offset current
Input BIAS current
Large signal voltage gain
Output voltage swing
Differential input resistance Ri
Input capacitance Ci
Common mode rejection ratio
Supply voltage rejection ratio
Slew rate
Gain bandwidth product
increases,the
SVRR is the ratio of the change in the input offset voltage to the corresponding
change in power supply voltages. This is expressed in V / V or in decibels,
SVRR can be defined as
SVRR = Vio / V
Where V is the change in the input supply voltage and Vio is the
corresponding change in the offset voltage.
For the 741C, SVRR = 150 V / V.
Because output signal amplitude is much large than the input signal the voltage
gain is commonly called large signal voltage gain. For 741C is voltage gain is
200,000 typically.
Slew Rate
The slew rate is the maximum rate of change of output voltage
for a step input voltage.
The slew rate makes the output voltage to change at a slower rate
than the applied input.
Eventually the output waveform is a distortion of the input
waveform.
The typical value for the slew rate is 0.5V/s.
Slew rate is defined as the maximum rate of change of output
voltage per unit of time and is expressed as volt per micro
second.
SR=(|dVo|/|ds|)max ie V\s