4.1 Semiconductions - Integrated Circuits Flashcards
what are integrated circuits?
arrangements of several electronic components in a common housing
what are the advantages and disadvantages of IC?
Ad:
very high density
very compact
resistant to mechanical stress
Dis:
requires additional cooling
can’t be repaired
what components are usually found on an IC?
Semiconductors
resistors
capicitors
which amplifier is always in the input stage?
Differential amplifier
what amp is usually in the output stage?
push-pull power amp
in operational amplifiers, how are the inputs designated?
inverting input designated - sign
non-inverting input designated + sign
in operation amplifiers, where is the output voltage measured?
between the output terminal and the common terminal
in operation amplifiers, what signals can they amplify?
both AC and DC
what is an ideal operational amplifier? (4)
-infinite amplification
-infinite input resistance
-input voltage bordering on zero
-small output resistance
in operation amplifiers, what are the voltages of the positive and negatives?
+/- 5 to 18v
in operation amplifiers, what is the result if the differential input voltage is positive?
negative output voltage
in operation amplifiers, what is the result if the differential input voltage is negative?
positive output voltage
what is a circuit with more than one op amp on a chip called?
Monolithically integrated analogue circuit
in operation amplifiers, what is the benefits of a Monolithically integrated analogue circuit? (4)
-minimum space requirements
-high reliability
-small characteristic variance
-low manufacturing costs
where are op amps extensively used?
-signal conditioning
-filtering
-mathematical operations
what are operational amplifiers designed to do?
a voltage amplifying device to be used with external feedback components to perform a variety of operations
dependent on which feedback component (resistor, capacitor or both)
what is amplifiers gain?
an op amps output signal
what are the classifications of op amps gain? (4)
voltage = voltage ‘in’ and voltage ‘out’
current = current ‘in’ and current ‘out’
transconductance = voltage ‘in’ and current ‘out’
transresistance = current ‘in’ and voltage ‘out’
in operational amplifiers, what is the output voltage signal equal to?
the difference between signals applied at its 2 inputs
in operational amplifiers, what should the output do if an identical common signal is detected?
it should ignore the signal and there should be no change of the output
in operational amplifiers, what is used for them to have very precise gain characteristics?
some form of negative feedback
in operational amplifiers, what is differential input voltage?
where it responds only to the difference between the voltages on its input terminals
in op amps, what is the ideal of open loop gain?
infinite
in op amps, what is open loop gain?
gain of the op-amp without positive or negative feedback
in op amps, what is the ideal for input impedance?
infinite
in op amps, what is input impedance?
ratio of input voltage to input current
in op amps, what is the ideal of output impedance?
zero
in op amps, what is the ideal for bandwidth?
infinite
in op amps, what is the ideal for offset voltage?
zero
in op amps, what is op amps bandwidth?
the frequency range over which voltage gain of the amplifier is above 70.7% or -3dB of max output
in op amps, at the detriment of high gain, but the gain of control of an op amp, what component is used to do this? and what is this called?
a suitable resistor across the amp from the output terminal to the inverting input
negative feedback
in op amps, how is negative feedback achieved? what is does this produce?
by feeding back a fraction of the output signal onto the input signal on the negative “inverting input” terminal.
a closed loop circuit
in op amps, what is effected through a closed loop circuit using negative feedback?
reduction of the amplifiers gain
what is summing point?
the total of original input signal and any feedback signals provided by the output
in inverting op amps, what are the two very important rules that they follow?
- no current flows into the input terminals
- v1 always equals v2
what does the negative sign mean in the closed loop voltage gain equation?
output signal being 180 degrees out of phase
due feedback negative in value
what is the construction of non-inverting op amp?
output voltage connected to the inverting “negative” terminal producing negative feedback.
input voltage connected directly to non-inverting terminal. output gain positive
what are the benefits of a non-inverting op amp in a closed loop config? (3)
-very good stability
-very high input impedance
-low output impedance
for overall closed loop gain, what will the value be?
always greater but never less than 1
positive
determined by the ratio of the values of Rf and R2
for overall closed loop gain, what will the value be if the Rf is zero?
exactly equal to 1
for overall closed loop gain, what will the value be if R2 is zero?
gain will approach inifity
how are amplifiers secured to protect them?
that neither a short circuit to ground, or short circuit to positive or negative terminals will destory the amplifier
what must a user do to op amps due to their sensitivity to high voltages?
compensate for asymmetry by external wiring
what is offset voltage?
the voltage required at the input terminals in order to set the output voltage to zero
at what voltage in the input terminals create a voltage at the output terminal?
potential of zero
what affects offset voltage compensation? (2)
-the amplifier used
-how they’re wired
in offset voltage compensation, how is a compensation voltage applied in a 709 series?
to the input terminal where there is no input voltage
in offset voltage compensation, how is a compensation voltage applied in a 741 series?
by a 10 kilo ohm potentiometer leaving input terminal free
in offset voltage compensation, how is a compensation voltage applied in a 748 series?
high-ohmic network leaving both input terminals free
