Characteristics of Operational Amplifier MCQ – Objective Question Answer for Operational Amplifier Characteristics Quiz

741SC is the different version of 741C IC, which is a commercial-grade op-amp with a higher slew rate and operates in the same temperature range.

µA748,  MC1558, µA741 and LM101 IC belongs to the second-generation op-amp. In that general-purpose op-amp’741’ is used widely in the greatest percentage of applications.

The advantage of a Hybrid Integrated Circuit is

A. Miniaturized circuits are made of individual components
B. Insulate components by protection
C. Circuit designer can choose the component value

In a hybrid integrated circuit, miniaturization can be achieved and allow the circuit designer complete freedom in choosing the resistor values, whereas a monolithic IC cannot use some important components in construction.

The metal can configuration of µA741 op-amp has eight pins with pin number 8 identified by a tab. The other pins are numbered counter-clockwise from pin 8, beginning with pin1.

There are two sets of electrical specifications. One set of specifications applies at room temperature of 25^oC, whereas the other set applies to the commercial temperature range from 0 to 70^oC.

The algebraic difference between the current into the inverting and non-inverting terminal is referred to as input offset current.

I_io  = |I_B1-I_B2| = |3.2 – 4.75| = |-1.55|

= > I_io  = +1.55mA.

Supply current is the current drawn by the op-amp from the power supply; this parameter is not given on most op-amp data. For 741c op-amp, the supply current I_s = 2.8mA response.

The rise time and percentage of overshoot are the characteristics of transient response.

As the electrical noise is random in nature, it is expressed as a root mean square value. The equivalent input noise voltage is expressed as square voltage (V²/Hz) and the equivalent input noise current as square noise current (A²/Hz).

When a signal is applied to the input of only one op-amp, some signal will appear at the output of another op-amp due to the physical closeness of op-amps in dual and quad packages, this causes the amplifier to amplifier coupling.

Channel separation is specified in the dual and quad op-amp datasheet because it is a measure of the amount of electrical coupling between op-amps that are integrated on the same chip.

Slew rate is one of the important factors in selecting the op-amp for ac application, particularly at relatively high frequencies application in oscillators, comparators, and filters.

The characteristics of the amplifier are included in the datasheet whereas, the application’s characteristics will not be included. Rather a collection of amplifier applications with circuit diagrams can be found in the datasheets.

For long-term stability, the amount of change in input offset voltage with time is crucial and denoted as microvolts per week.

The output offset voltage is expressed as a function of input offset current and the input offset voltage when is given as

V_ooT  = [1+(R_F/R₁)] × (V_io) + (R_F × I_o).

In practice, the output offset voltage in all op-amp circuits will change with time. Therefore, to maintain a system’s desired accuracy and linearity, it is necessary to calibrate all op-amps in that system periodically.

For LH0041C,

△V_io/△t = 5µV/week and △I_io /△t = 2nA/week.

Due to the time drift △t = 12 weeks (3months). The maximum possible change in output offset voltage,

△V_ooT  = [[1+(R_F/R₁)] × (△V_io/△t) × △t]+[R_F × (△I_io/△t) × △t] = [(1+(250kΩ/1kΩ)) × 5µV × 12] + [250kΩ × 2µA × 12] =

15.1mv+6mv

= > △V_ooT  = 21.1mv.

The amount of drift in the input signal depends on the relative values of external components. So, if relatively small values are selected for an external component then drift can be minimized.

The peak-to-peak output swing depends on the value of the supply voltage ( which is +15v-(-15v) = 30v ) and is always less than the value to maintain the safe operation of the op-amp.

If the power consumption as a function of the supply voltage curve is drawn, it can be seen that the amount of dc power required to operate the op-amp under no-load conditions increases with an increase in supply voltage.